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2-Aminoethoxydiphenyl borate (2-APB) is a reliable blocker of store-operated Ca²⁺ entry but an inconsistent inhibitor of InsP₃-induced Ca²⁺ release

Laboratory of Molecular Signalling, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK

¹Correspondence: Laboratory of Molecular Signalling, The Babraham Institute, Babraham, Cambridge CB2 4AT, UK. E-mail: martin.bootman{at}bbsrc.ac.uk

	ABSTRACT

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
Since its introduction to Ca²⁺ signaling in 1997, 2-aminoethoxydiphenyl borate (2-APB) has been used in many studies to probe for the involvement of inositol 1,4,5-trisphosphate receptors in the generation of Ca²⁺ signals. Due to reports of some nonspecific actions of 2-APB, and the fact that its principal antagonistic effect is on Ca²⁺ entry rather than Ca²⁺ release, this compound may not have the utility first suggested. However, 2-APB has thrown up some interesting results, particularly with respect to store-operated Ca²⁺ entry in nonexcitable cells. These data indicate that although it must be used with caution, 2-APB can be useful in probing certain aspects of Ca²⁺ signaling.—Bootman, M. D., Collins, T. J., Mackenzie, L., Roderick, H. L., Berridge, M. J., Peppiatt, C. M. 2-Aminoethoxydiphenyl borate (2-APB) is a reliable blocker of store-operated Ca²⁺ entry but an inconsistent inhibitor of InsP₃-induced Ca²⁺ release.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
OF THE MULTIPLE presently recognized mechanisms of mobilizing intracellular Ca²⁺ stores (1) , the pathway involving release of Ca²⁺ by inositol 1,4,5-trisphosphate (InsP₃) has possibly the least useful membrane-permeant pharmacology. Ryanodine receptors in intact cells, for example, can be rapidly activated by caffeine and specifically inhibited in a use-dependent manner by ryanodine (for reviews, see refs 2 , 3 ). InsP₃ receptors (InsP₃Rs) can be specifically activated using a membrane-permeant InsP₃ ester (4 ; for example, see ref 5 ), but the choice of antagonists of InsP₃ action is limited. One of the most commonly used InsP₃R antagonists is heparin. This compound is limited because it has multiple actions, including uncoupling G-protein signaling and activating ryanodine receptors (for reviews, see refs 2 , 6 ). Furthermore, heparin has to be either injected or infused into cells, although it has been suggested that low molecular weight heparin species may cross the plasma membrane and thus inhibit InsP₃Rs within intact cells (7) . Xestospongins, which were first described as specific membrane-permeant InsP₃R antagonists by Pessah and colleagues (8) , have been used many times to prove whether InsP₃Rs are involved in particular responses. Although there are many examples of xestospongin inhibiting Ca²⁺ signaling, its mechanism of action has not been fully elucidated. Xestospongin is expensive, often slow to act, and has not been successful in all labs. It was against this backdrop of a shortage of rapidly working, low-cost membrane-permeant antagonists of phosphoinositide signaling that 2-APB appeared to have great potential.

Although there are numerous examples of 2-APB inhibiting Ca²⁺ signaling in intact cells, its mechanism of action is unclear. In addition to attenuating the release of internal Ca²⁺ stores, 2-APB can also inhibit the store-operated channels (SOCs) that replenish the Ca²⁺ pool, suggesting that the inhibition of SOC may be a primary target for 2-APB.

	SPECIFIC ACTIONS OF 2-APB ON Ca2+ RELEASE BY InsP3 RECEPTORS

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
The initial report by Mikoshiba and colleagues demonstrated that 2-APB gave a concentration-dependent inhibition of InsP₃-induced Ca²⁺ release from mouse cerebellar membranes without affecting InsP₃ binding (9) . It did not modulate InsP₃ production in platelets nor did it affect Ca²⁺ release from striated muscle vesicles activated by modest concentrations of caffeine, signifying that it did not interact with ryanodine receptors. Smooth muscle cell contraction in response to an InsP₃-generating stimulus was inhibited by 2-APB, whereas that triggered by KCl-induced depolarization was unaffected, suggesting there was an effect on neither voltage-operated Ca²⁺ entry nor the contractile machinery. 2-APB appeared to be rapidly cell permeant. Most of the claims made in the study by Maruyama et al. (9) have been substantiated by later studies, although 2-APB does not appear to be equally potent at inhibiting InsP₃-induced Ca²⁺ release in all cell types.

Ironically, the inhibitory effect of 2-APB on Ca²⁺ release via InsP₃Rs is perhaps the most controversial of its actions. The cell types where 2-APB has been shown to have effects consistent with inhibition of InsP₃-induced Ca²⁺ release include platelets (9 , 10) , suprachiasmatic nucleus (11) , ventricular cardiomyocytes (12) , various types of smooth muscle (9 , 13 14 15 16 17 18) , toad sinus venosus (19) , pancreatic ß cells (20) , fungal growth tips (21) , hippocampal neurons (22) , skeletal myotubes (23) , neutrophils (24) , and endothelial cells (25) . Generally, these studies found that over the range 1–100 µM, 2-APB inhibited Ca²⁺ signals due to the release of intracellular stores and subsequent Ca²⁺ entry. However, in many of these studies, 2-APB has been used to demonstrate the involvement of InsP₃Rs without consideration of additional effects.

Results obtained using permeabilized cells, cell membranes, and intact cells suggest that 2-APB may not be a consistent blocker of InsP₃Rs. Whereas Maruyama et al. (9) and others (e.g., refs 26 , 27 ) found that InsP₃-induced Ca²⁺ release in permeabilized cells was inhibited in a concentration-dependent manner by 2-APB, different studies have reported either weak inhibition or no effect on InsP₃-induced Ca²⁺ release (e.g., 28 ).

Why 2-APB has such a variable effect on InsP₃-induced Ca²⁺ release in intact or permeabilized cells is unclear. One possibility, suggested by Kukkonen et al. (29) , is that 2-APB shows selectivity for different InsP₃R isoforms. Consistent with this notion, some of the most prominent effects of 2-APB have been seen in cell types that largely express types 1 and 3 InsP₃Rs, whereas cells that express largely type 2 InsP₃Rs seem to be insensitive. However, there are exceptions to this rule, which suggests it is perhaps only a partial explanation. An alternative possibility derives from the mixed mode of inhibition of InsP₃-induced Ca²⁺ release by 2-APB. The inhibitory effect of 2-APB can be partially out-competed by increasing InsP₃ concentration. The IC₅₀ for inhibition of InsP₃-evoked Ca²⁺ release is therefore dependent on the ambient InsP₃ concentration. In experiments by Maruyama et al. (9) , Ca²⁺ released from cerebellar membranes by 100 nM InsP₃ was inhibited by 2-APB with an IC₅₀ of 10–20 µM. The maximal response of cerebellar microsomes to InsP₃ is achieved with 10 µM InsP₃; at this concentration of InsP₃, the IC₅₀ for 2-APB is 1 mM (J. Bilmen and F. Michelangeli, personal communication). The discrepant effects of 2-APB in blocking agonist-induced Ca²⁺ release in intact cells may therefore indicate that different cell types generate substantially varying levels of InsP₃. However, this is also likely to be only a partial explanation, since the same concentrations of 2-APB and InsP₃ have been shown to have contrasting effects in different cell types (e.g., compare refs 27 , 28 ). Although there is no apparent resolution to the divergent effects of 2-APB on InsP₃-induced Ca²⁺ release in different studies, these data do highlight the need for caution in simply using 2-APB as an InsP₃R antagonist. In some situations, 2-APB attenuates Ca²⁺ signaling without modulating Ca²⁺ flux through InsP₃Rs. In these cases, the action of 2-APB can be explained by inhibition of Ca²⁺ entry.

	SPECIFIC ACTIONS OF 2-APB ON Ca2+ ENTRY THROUGH SOCs

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
Even though the data presented by Maruyama et al. (9) made a reasonable case for 2-APB acting as a specific membrane-permeable InsP₃R antagonist, emerging data show that its primary action on cells is not to block Ca²⁺ release, but rather to inhibit SOC influx. The study that really brought 2-APB into the limelight—demonstrating the involvement of InsP₃Rs in coupling to SOC channels (30) —must be interpreted in the light that 2-APB can inhibit SOC directly without involvement of InsP₃Rs (27 , 28 , 31 32 33 34) .

Despite its widespread use, there is presently no clear-cut evidence for 2-APB inhibiting Ca²⁺ signaling by solely targeting InsP₃Rs. At best, it seems that in some cells 2-APB can inhibit both agonist-induced Ca²⁺ release and the concomitant SOC with the same efficacy (e.g., refs 16 , 27 ). In contrast, there are several studies of intact cells where 2-APB was found not to inhibit InsP₃-induced Ca²⁺ release, but it could still block Ca²⁺ entry. For example, Barritt and colleagues (28) found that concentrations of 2-APB of up to 100 µM had no effect on Ca²⁺ release during vasopressin stimulation of primary hepatocytes, but it did cause a concentration-dependent inhibition of Ca²⁺ influx with an IC₅₀ of 10 µM. Thapsigargin-induced Ca²⁺ influx was inhibited with a comparable concentration dependence. A similar effect of 2-APB inhibiting SOC without affecting Ca²⁺ release has been demonstrated for CHO cells (29) .

The best evidence for 2-APB inhibiting SOC through a mechanism not involving InsP₃Rs is that it is still effective in cells that do not express InsP₃Rs at all (27 , 31 , 34 , 35) . Activation of Drosophila photoreceptors relies on the gating of light-activated cation channels in the plasma membrane of these cells. It is well established that the InsP₃Rs expressed in Drosophila photoreceptors are not necessary for vision, yet 2-APB still blocked light-induced cation entry (27 , 36) .

2-APB does not inhibit SOC when internally perfused within cells (31 , 32) or applied to the cytosolic surface of excised membrane patches (33) . Extracellularly applied 2-APB inhibits SOC in platelets with no measurable delay, similar to inorganic ions such as lanthanum (37) . These data indicate that 2-APB blocks SOC by interacting at the outside of cells. The manner in which 2-APB prevents SOC is unclear. The agonist-induced activation of the putative SOC channel TRP3 heterologously expressed in HEK cells was inhibited by 2-APB whereas activation of the same channel by diacylglycerol analogs was not (30) . Similarly, in Drosophila photoreceptors, 2-APB blocked light-induced cation entry but not that evoked by metabolic stress (36) . If 2-APB simply occluded these channels, it should prevent their activation by any means. These data therefore suggest that 2-APB probably does not bind directly to the channels, but rather interacts upstream in their activation mechanism (see also ref 38 ).

If 2-APB is to be used as a SOC inhibitor, it is essential that it has good selectivity for those channels. The original study demonstrated that it had no effect on voltage-operated Ca²⁺ channels (9) , a finding supported by several other studies (11 , 13 , 16 , 19 , 23) . Several other non-voltage-activated Ca²⁺ entry pathways that are distinct from SOC are not inhibited by 2-APB, including S-nitrosylation-induced influx in a smooth muscle cell line (39) , maitotoxin-evoked Ca²⁺ entry in hepatocytes (28) , Ca²⁺ influx caused by diacylglycerol analogs in PC12 cells (40) , muscarinic activation of nonselective cation channels in smooth muscle (41) , and arachidonate-stimulated Ca²⁺ channels in HEK293 cells (38) and HeLa cells (authors’ unpublished observations).

Despite its lack of action on the non-SOC Ca²⁺ entry pathways listed above, 2-APB is not completely specific for SOC channels, as it has been shown to inhibit MagNuM channels (also known as LTRPC7 and TRP-PLIK; ref 42 ). MagNuM is a widely expressed ion channel that conducts Ca²⁺ and Mg²⁺ at negative membrane potentials. This channel is not regulated by store depletion, but instead is activated by a decrease in intracellular levels of magnesium nucleotides (43) . Although SOC and MagNuM may be difficult to discriminate if they are simultaneously switched on, since the latter is not activated by store depletion it is likely that the flux of Ca²⁺ through this channel will not be appreciably altered by mild treatments that activate SOC. Under many experimental conditions, therefore, it is likely that a block of Ca²⁺ entry by 2-APB would reflect and affect SOC channels rather than MagNuM. In rat basophilic leukemia cells, the effect of 2-APB on MagNuM was rapidly reversible whereas its effects on SOC were not (42) . The reversibility of 2-APB may therefore provide a means of discriminating between different targets.

2-APB also modifies the conductance through CaT1 channels (44) . These channels were suggested to underlie I_CRAC, a well-characterized form of SOC (45) . However, whereas 2-APB irreversibly inhibits I_CRAC, it reversibly potentiates the conductance of CaT1 channels, suggesting they are not the same (44) .

At present, the bulk of data supports the notion that 2-APB is an almost universal blocker of SOC and some TRP isoforms (35) while being a rather variable inhibitor of InsP₃-induced Ca²⁺ release. Whereas substantially different concentrations of 2-APB are needed to inhibit InsP₃-induced Ca²⁺ release in different cell types, SOC is generally fully inhibited by 50–100 µM 2-APB. The present exceptions to this are SH-SY5Y cells, which appear to be completely insensitive to 2-APB (29) , and neutrophils where Ca²⁺ signals in response to platelet-activating factor were totally blocked by 100 nM 2-APB (46) .

	POTENTIALLY UNHELPFUL ACTIONS OF 2-APB

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
In addition to its effects on InsP₃-induced Ca²⁺ release and SOC, 2-APB has been shown to enhance the nonspecific leak of Ca²⁺ from the intracellular Ca²⁺ pool (26) and to inhibit the SERCA pumps responsible for loading intracellular Ca²⁺ stores (9 , 26) . Consistent with the enhancement of a Ca²⁺ leak, in some intact cell studies 2-APB caused a rise in basal Ca²⁺ levels (9 , 10 , 12 , 28) . When applied to electrically paced cardiac myocytes at concentrations 10 µM, 2-APB caused a transient increase in the amplitude of systolic Ca²⁺ rises, followed by a progressive diminution of the electrically evoked responses (authors’ unpublished observations). This effect is consistent with an inhibition of SERCA activity leading initially to an enhanced response due to less Ca²⁺ sequestration, but the lack of Ca²⁺ store refilling eventually leads to a failure of excitation-contraction coupling.

2-APB prevents mitochondria from releasing Ca²⁺ they have sequestered (31) , possibly by an inhibitory action on the sodium/Ca²⁺ exchanger. We have found that 2-APB at 100 µM causes mitochondria to swell and change shape, but without causing them to depolarize (authors’ unpublished observations).

These actions of 2-APB may render it useless in some situations. However, in experimental protocols investigating SOC activity, the intracellular Ca²⁺ pool is often completely discharged by application of substances such as thapsigargin. Under those conditions, any effect of 2-APB on the Ca²⁺ leak or SERCAs would be irrelevant. Although mitochondria and intracellular Ca²⁺ signaling systems communicate bidirectionally, the effect of inhibiting mitochondrial Ca²⁺ release on a particular response can be directly tested by using the sodium/Ca²⁺ exchange blocker GCP37157 (47) .

Another potentially limiting feature of 2-APB is that it is poorly reversible in some cell types. In toad sinus venosus, for example, it took > 1 h for the inhibitory effects of 60 µM 2-APB to be reversed (19 , see also refs 27 , 31 , 32 ). These data contrast with other studies where the inhibitory effects 2-APB were reversed within a few minutes (28) or even immediately (36) . In studies of cardiac myocytes, we have found that the concentration of 2-APB applied to cells determined its reversibility. 2-APB inhibited spontaneous diastolic Ca²⁺ transients evoked by endothelin 1. At concentrations of < 5 µM, this effect was readily reversible, whereas higher concentrations gave a prolonged inhibition (unpublished results).

Some of the discrepant effects of 2-APB may be due to its ability to exist as different species. Besides the open-chain monomeric form, it has been suggested to dimerize (39) and form a monomeric heterocyclic compound with an internal coordinate nitrogen-boron bond (10) . It was proposed that 2-APB dimers resemble Xestospongins, indicating a common mechanism of action (39) , but this seems unlikely (10) . A comparison of structural analogs of 2-APB that inhibit Ca²⁺ signaling in platelets has suggested that the diphenyl moiety is important for its activity (10) .

The pK_b of 2-APB is 10, which means that in physiological pH its amine group will be protonated, giving the molecule a net positive charge (J. Bilmen and F. Michelangeli, personal communication; ref 10 ). We have found that 2-APB causes a rapid cytoplasmic acidification that is slowly reversible, suggesting that it either carries protons across the membrane or displaces them from internal sites (authors’ unpublished observations).

	SIMILARITY BETWEEN THE ACTIONS OF 2-APB AND XESTOSPONGIN

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
The observations of multiple conflicting effects of 2-APB may also sound a note of caution for users of Xestospongins. Ironically, Xestospongins have been used in more studies than 2-APB, yet we probably know more about the latter compound. In several studies, the results of using 2-APB and Xestospongins have been the same, and their common effect interpreted as clear evidence for involvement of InsP₃Rs (e.g., refs 25 , 30 ). However, since the interpretation of data obtained using 2-APB has to be reevaluated in the light of its action on SOC, so Xestospongin cannot simply be regarded as an InsP₃R antagonist. Indeed, Xestospongin is capable of inhibiting SOC in DT40 cells where InsP₃Rs are absent (D. L. Gill, personal communication). Just like 2-APB, Xestospongin can inhibit SERCAs (48) and cause release of Ca²⁺ from stores in intact cells (e.g., 49 ). There is a striking similarity between Xestospongin and 2-APB in the range of targets (SOC, InsP₃Rs, SERCA) and in their rather variable action on different cell types.

	POTENTIATION OF Ca2+ SIGNALING BY 2-APB

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
Although much of the data obtained using 2-APB have suggested that it blocks Ca²⁺ signaling in intact cells, there are several reports of 2-APB enhancing Ca²⁺ release and Ca²⁺ entry. In rat basophilic leukemia cells and Jurkat cells, I_CRAC had a biphasic dependence on 2-APB concentration; it was potentiated by low micromolar concentrations of 2-APB and inhibited by higher levels of 2-APB (31) . This was independent of any effects of 2-APB on InsP₃Rs, since I_CRAC in DT40 cells not expressing InsP₃Rs showed a similar biphasic dependence on 2-APB concentration (31 ; but see ref 44 ). A transient facilitation of the light-induced current by 2-APB was observed in Drosophila photoreceptors (36) . 2-APB potentiated Ca²⁺ signals in mouse pancreatic cells during agonist stimulation or during internal perfusion with InsP₃ (50) .

The enhanced leak of Ca²⁺ from the endoplasmic reticulum and inhibition of SERCA activity by 2-APB may underlie some of the observed potentiation of Ca²⁺ signaling and the suggestion that 2-APB may act as an agonist of InsP₃Rs (51) . Ca²⁺ that is nonspecifically released by stores can positively stimulate further InsP₃ production or Ca²⁺ release (e.g., 52 ). Removal of Ca²⁺ sequestration by SERCA inhibition will remove a negative feedback component from the responses. Therefore, whereas potentiatory effects of 2-APB on Ca²⁺ entry might reflect modulation of channels (31) , enhancement of Ca²⁺ release probably reflects actions of 2-APB on the Ca²⁺ leak and SERCAs.

	SUMMARY

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 
2-APB has been rapidly adopted as an InsP₃R antagonist by the Ca²⁺ signaling community. However, 2-APB cannot simply be used as an InsP₃R antagonist in most situations, since it has multiple targets and can potentiate some Ca²⁺ responses. Inhibition of InsP₃-mediated Ca²⁺ release by 2-APB is extremely variable between studies. An almost universal observation is that 2-APB inhibits SOC. However, this is not via an effect on InsP₃Rs, nor is it due to direct blocking of the Ca²⁺ entry channels. The multiple actions of 2-APB are strikingly similar to those of Xestospongin, implying that the data obtained with both compounds must be interpreted cautiously. Despite the many effects of 2-APB, it does have uses, for example, in investigating the activation of SOC and in discriminating between different forms of Ca²⁺ entry. Careful titration of 2-APB concentration may allow inhibition of InsP₃-induced Ca²⁺ release and SOC without significant SERCA inhibition or nonspecific Ca²⁺ release. In many situations 2-APB cannot be regarded as a marker for the involvement of InsP₃Rs in the generation of Ca²⁺ signals.

	REFERENCES

TOP ABSTRACT INTRODUCTION SPECIFIC ACTIONS OF 2-APB... SPECIFIC ACTIONS OF 2-APB... POTENTIALLY UNHELPFUL ACTIONS OF... SIMILARITY BETWEEN THE ACTIONS... POTENTIATION OF Ca2+ SIGNALING... SUMMARY REFERENCES

 

1. Bootman, M. D., Collins, T. J., Peppiatt, C. M., Prothero, L. S., MacKenzie, L., De Smet, P., Travers, M., Tovey, S. C., Seo, J. T., Berridge, M. J., Ciccolini, F., Lipp, P. (2001) Calcium signalling—an overview. Semin. Cell Dev. Biol. 12,3-10[CrossRef][Medline]
2. Ehrlich, B. E., Kaftan, E., Bezprozvannaya, S., Bezprozvanny, I. (1994) The pharmacology of intracellular Ca²⁺-release channels. Trends Pharmacol. Sci. 15,145-149[CrossRef][Medline]
3. Berridge, M. J., Cheek, T. R., Bennett, D. L., Bootman, M. D. (1995) Ryanodine receptors and intracellular calcium signalling. Sorrentino, V. eds. Ryanodine Receptors: A CRC Pharmacology and Toxicology Series. Basic and Clinical Aspects ,119-154
4. Li, W., Schultz, C., Llopis, J., Tsien, R. Y. (1997) Membrane-permeant esters of inositol polyphosphates, chemical syntheses and biological applications. Tetrahedron 53,12017-12040[CrossRef]
5. Thomas, D., Lipp, P., Tovey, S. C., Berridge, M. J., Li, W. H., Tsien, R. Y., Bootman, M. D. (2000) Microscopic properties of elementary Ca²⁺ release sites in non-excitable cells. Curr. Biol. 10,8-15[CrossRef][Medline]
6. Taylor, C. W., Broad, L. M. (1998) Pharmacological analysis of intracellular Ca²⁺ signalling: problems and pitfalls. Trends Pharmacol. Sci. 19,370-375[CrossRef][Medline]
7. Jonas, S., Sugimori, M., Llinas, R. (1997) Is low molecular weight heparin a neuroprotectant?. Ann. N.Y. Acad. Sci. 825,389-393[Abstract/Free Full Text]
8. Gafni, J., Munsch, J. A., Lam, T. H., Catlin, M. C., Costa, L. G., Molinski, T. F., Pessah, I. N. (1997) Xestospongins: potent membrane permeable blockers of the inositol 1,4,5-trisphosphate receptor. Neuron. 19,723-733[CrossRef][Medline]
9. Maruyama, T., Kanaji, T., Nakade, S., Kanno, T., Mikoshiba, K. (1997) 2APB, 2-aminoethoxydiphenyl borate, a membrane-penetrable modulator of Ins(1,4,5)P-3-induced Ca²⁺ release. Jpn. J. Biochem. 122,498-505
10. Dobryndeva, Y., Blackmore, P. (2001) 2-aminoethoxydiphenyl borate directly inhibits store-operated calcium entry channels in human platelets. Mol. Pharmacol. 60,541-552[Abstract/Free Full Text]
11. Hamada, T., Liou, S.-Y., Fukushima, T., Maruyama, T., Watanabe, S., Mikoshiba, K., Ishida, N. (1999) The role of inositol trisphosphate-induced Ca²⁺ release from IP₃-receptor in the rat suprachiasmatic nucleus on circadian entrainment mechanism. Neurosci. Lett. 263,125-128[CrossRef][Medline]
12. Gysembergh, A., Lemaire, S., Piot, C., Spotouch, C., Richard, S., Kloner, R. A., Przyklenk, K. (1999) Pharmacological manipulation of Ins(1,4,5)P₃ signalling mimics preconditioning in rabbit heart. Am. J. Physiol. 277,H2458-H2469[Abstract/Free Full Text]
13. Ascher-Landsberg, J., Saunders, T., Elovitz, M., Phillipe, M. (1999) The effects of 2-aminoethoxydiphenyl borate, a novel inositol 1,4,5-trisphosphate receptor modulator on myometrial contractions. Biochem. Biophys. Res. Commun. 264,979-982[CrossRef][Medline]
14. Imaeda, K., Yamamoto, Y., Fukuta, H., Koshita, M., Suzuki, H. (2000) Hyperpolarisation-induced dilatation of submucosal arterioles in the guinea-pig ileum. Br. J. Pharmacol. 131,1121-1128[CrossRef][Medline]
15. Sherer, E. Q., Wonneberger, K., Wangemman, P. (2001) Differential desensitisation of Ca²⁺ mobilisation and vasoconstriction by ET_A receptors in the gerbil spiral modiolar artery. J. Membr. Biol. 182,183-191[CrossRef][Medline]
16. Potocnik, S. J., Hill, M. A. (2001) Pharmacological evidence for capacitative Ca²⁺ entry in cannulated and pressurized skeletal muscle arterioles. Br. J. Pharmacol. 134,247-256[CrossRef][Medline]
17. Hirst, G. D. S., Edwards, F. R. (2001) Generation of slow waves in the antral region of guinea-pig stomach—a stochastic process. J. Physiol. (London) 535,165-180[Abstract/Free Full Text]
18. Sergeant, G. P., Hollywood, M. A., McCloskey, K. D., McHale, N. G., Thornbury, K. D. (2001) Role of IP₃ in modulation of spontaneous activity in pacemaker cells of rabbit urethra. Am. J. Physiol. 280,C1349-C1356[Abstract/Free Full Text]
19. Bramich, N. J., Cousins, H. M., Edwards, F. R., Hirst, G. D. S. (2001) Parallel metabotropic pathways in the heart of the toad. Bufo marinus. Am. J. Physiol. 281,H1771-H1777
20. Dyachok, O., Gylfe, E. (2001) Store-operated influx of Ca²⁺ in pancreatic ß cells exhibits graded dependence on the filling of the endoplasmic reticulum. J. Cell Sci. 114,2179-2186[Abstract/Free Full Text]
21. Silverman-Gavrila, L. B., Lew, R. P. (2001) Regulation of the tip-high [Ca²⁺] gradient in growing hyphae of the fungus Neurospora crassa. Eur. J. Cell Biol. 80,379-390[CrossRef][Medline]
22. Pal, S., Sun, D., Limbrick, D., Rafiq, A., DeLorenzo, R. J. (2001) Epileptogenesis induces long-term alterations in intracellular calcium release and sequestration mechanisms in the hippocampal neuronal culture model of epilepsy. Cell Calcium 30,285-296[CrossRef][Medline]
23. Estrada, M., Cardenas, C., Liberona, J. L., Carrasco, M. A., Mignery, G. A., Allen, P. D., Jaimovich, E. (2001) Calcium transients in 1B5 myotubes lacking ryanodine receptors are related to inositol trisphosphate receptors. J. Biol. Chem. 276,22868-22874[Abstract/Free Full Text]
24. Hauser, C. J., Fekete, Z., Adams, J. M., Garced, M., Livingston, D. H., Deitch, E. A. (2001) PAF-mediated Ca²⁺ influx in human neutrophils occurs via store-operated mechanisms. J. Leukoc. Biol. 69,63-68[Abstract/Free Full Text]
25. Bishara, N. B., Murphy, T. V., Hill, M. A. (2002) Capacitative Ca²⁺ entry in vascular endothelial cells is mediated via pathways sensitive to 2 amino ethoxydiphenyl borate and xestospongin C. Br. J. Pharmacol. 135,119-128[CrossRef][Medline]
26. Missiaen, L., Callewaert, G., De Smedt, H., Parys, J. B. (2001) 2-aminoethoxydiphenyl borate affects the inositol 1,4,5-trisphosphate receptor, the intracellular Ca²⁺ pump and the non-specific leak from the non-mitochondrial Ca²⁺ stores in permeabilised A7r5 cells. Cell Calcium 29,111-116[CrossRef][Medline]
27. Ma, H.-T., Venkatachalam, K., Li, H.-S., Montell, C., Kurosaki, T., Patterson, R. L., Gill, D. L. (2001) Assessment of the role of the inositol 1,4,5-trisphosphate receptor in the activation of transient receptor potential channels and store-operated Ca²⁺ entry. J. Biol. Chem. 276,18888-18896[Abstract/Free Full Text]
28. Gregory, R. B., Rychkov, G., Barritt, G. J. (2001) Evidence that 2-aminoethoxydiphenyl borate is a novel inhibitor of store-operated Ca²⁺ channels in liver cells, and acts through a mechanism which does not involve inositol trisphosphate receptors. Biochem. J. 354,285-290[CrossRef][Medline]
29. Kukkonen, J. P., Lund, P.-E., Åkerman, K. E. O. (2001) 2-aminoethoxydiphenyl borate reveals heterogeneity in receptor-activated Ca²⁺ discharge and store-operated Ca²⁺ influx. Cell Calcium 30,117-129[CrossRef][Medline]
30. Ma, H.-T., Patterson, R. L., van Rossum, D. B., Birnbaumer, L., Mikoshiba, K., Gill, D. L. (2000) Requirement of the inositol trisphosphate receptor for activation of store-operated Ca²⁺ channels. Science 287,1647-1651[Abstract/Free Full Text]
31. Prakriya, M., Lewis, R. S. (2001) Potentiation and inhibition of Ca²⁺ release-activated Ca²⁺ channels by 2-aminoethyldiphenyl borate (2-APB) occurs independently of IP₃ receptors. J. Physiol. (London) 536,3-19[Abstract/Free Full Text]
32. Bakowski, D., Glitsch, M. D., Parekh, A. B. (2001) An examination of the secretion-like coupling model for the activation of the Ca²⁺ release-activated Ca²⁺ current I_CRAC in RBL-1 cells. J. Physiol. (London) 532,55-71[Abstract/Free Full Text]
33. Braun, F.-J., Broad, L. M., Armstrong, D. L., Putney, J. W. (2001) Stable activation of single Ca²⁺-release activated Ca²⁺ channels in divalent cation-free solutions. J. Biol. Chem. 276,1063-1070[Abstract/Free Full Text]
34. Broad, L. M., Braun, F.-J., Lievremont, J.-P., Bird, G. St. J., Kurosaki, T., Putney, J. W. (2001) Role of the phospholipase C-inositol 1,4,5-trisphosphate pathway in calcium release-activated calcium current and capacitative calcium entry. J. Biol. Chem. 276,15945-15952[Abstract/Free Full Text]
35. Iwaski, H., Mori, Y., Hara, Y., Uchida, K., Zhou, H., Mikoshiba, K. (2001) 2-aminoehtoxydiphenyl borate (2-APB) inhibits capacitative calcium entry independently of the function of inositol 1,4,5-trisphosphate receptors. Receptors Channels 7,429-439[Medline]
36. Chorna-Ornan, I., Joel-Almagor, T., Ben-Ami, H. C., Frechter, S., Gillo, B., Selinger, Z., Gill, D. L., Minke, B. (2001) A common mechanism underlies vertebrate calcium signalling and Drosophila phototransduction. J. Neurosci. 21,2622-2629[Abstract/Free Full Text]
37. Diver, J. M., Sage, S. O., Rosado, J. A. (2001) The inositol trisphosphate receptor antagonist 2-aminoethoxydiphenylborate (2-APB) blocks Ca²⁺ entry channels in human platelets: cautions for its use in studying Ca²⁺ influx. Cell Calcium 30,323-329[CrossRef][Medline]
38. Luo, D., Broad, L. M., Bird, G. St. J., Putney, J. W. (2001) Mutual antagonism of calcium entry by capacitative and arachidonic acid-mediated calcium entry pathways. J. Biol. Chem. 276,20186-20189[Abstract/Free Full Text]
39. Van Rossum, D. B., Patterson, R. L., Ma, H.-T., Gill, D. L. (2000) Ca²⁺ entry mediated by store depletion, S-nitrosylation and TRP3 channels. J. Biol. Chem. 275,28562-28568[Abstract/Free Full Text]
40. Tesfai, Y., Brereton, H. M., Barritt, G. J. (2001) A diacylglycerol-activated Ca²⁺ channel in PC12 cells (an adrenal chromaffin cell line) correlates with expression of the TRP-6 (transient receptor potential) protein. Biochem. J. 358,717-726[CrossRef][Medline]
41. Jezior, J. R., Brady, J. D., Rosenstein, D. I., McCammon, K. A., Miner, A. S., Ratz, P. H. (2001) Dependency of detrusor contractions on calcium sensitization and calcium entry through LOE-908-sensitive channels. Br. J. Pharmacol. 134,78-87[CrossRef][Medline]
42. Hermosura, M. C., Monteilh-Zoller, M. K., Scharenberg, A. M., Penner, R., Fleig, A. (2002) Dissociation of the store-operated calcium current I_CRAC and the Mg-nucleotide-regulated metal ion current MagNuM. J. Physiol. (London) 539,445-458[Abstract/Free Full Text]
43. Nadler, M. J. S., Hermosura, M. C., Inabe, K., Perraud, A. L., Zhu, Q. Q., Stokes, A. J., Kurosaki, T., Kinet, J. P., Penner, R., Scharenberg, A. M., Fleig, A. (2001) LTRPC7 is a MgATP-regulated divalent cation channel required for cell viability. Nature (London) 411,590-595[CrossRef][Medline]
44. Voets, T., Prenen, J., Fleig, A., Vennekens, R., Watanabe, H., Hoenderop, J. G. J., Bindels, R. J. M., Droogmans, G., Penner, R., Nilius, B. (2001) CaT1 and the calcium release-activated calcium channel manifest distinct pore properties. J. Biol. Chem. 276,47767-47770[Abstract/Free Full Text]
45. Yue, L. X., Peng, J. B., Hediger, M. A., Clapham, D. E. (2001) CaT1 manifests the pore properties of the calcium-release-activated calcium channel. Nature (London) 410,705-709[CrossRef][Medline]
46. Hauser, C. J., Fekete, Z., Adams, J. M., Garced, M., Livingston, D. H., Deitch, E. A. (2001) PAF-mediated Ca²⁺ influx in human neutrophils occurs via store-operated mechanisms. J. Leukoc. Biol. 69,63-68[Abstract/Free Full Text]
47. Collins, T. J., Lipp, P., Berridge, M. J., Bootman, M. D. (2001) Mitochondrial Ca²⁺ uptake depends on the spatial and temporal profile of cytosolic Ca²⁺ signals. J. Biol. Chem. 276,26411-26420[Abstract/Free Full Text]
48. De Smet, P., Parys, J. B., Callewaert, G., Weidema, A. F., Hill, E., De Smedt, H., Erneux, C., Sorrentino, V., Missiaen, L. (1999) Xestospongin C is an equally potent inhibitor of the inositol 1,4,5-trisphosphate receptor and the endoplasmic-reticulum Ca²⁺ pumps. Cell Calcium 26,9-13[CrossRef][Medline]
49. Broad, L. M., Cannon, T. R., Taylor, C. W. (1999) A non-capacitative pathway activated by arachidonic acid is the major Ca²⁺ entry mechanism in rat A7r5 smooth muscle cells stimulated with low concentrations of vasopressin. J. Physiol. (London) 517,121-134[Abstract/Free Full Text]
50. Wu, J., Kamimura, N., Takeo, T., Suga, S., Wakui, M., Maruyama, T., Mikoshiba, K. (2000) 2-aminoethoxydiphenyl borate modulates kinetics of intracellular Ca²⁺ signals mediated by inositol 1,4,5-trisphosphate-sensitive Ca²⁺ stores in single pancreatic acinar cells of mouse. Mol. Pharmacol. 58,1368-1374[Abstract/Free Full Text]
51. Ma, H.-T., Venkatachalam, K., Parys, J. B., Gill, D. L. (2002) Modification of store-operated channel-coupling and InsP₃ receptor-function by 2-aminoethoxydiphenyl borate in DT40 lymphocytes. J. Biol. Chem. 277,6915-6922[Abstract/Free Full Text]
52. Smith, P. M., Gallacher, D. V. (1994) Thapsigargin-induced Ca²⁺ mobilization in acutely isolated mouse lacrimal acinar cells is dependent on a basal level of Ins(1,4,5)P₃ and is inhibited by heparin. Biochem. J. 299,37-40

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