HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: fj.07-9097comv1 fj.07-9097comv2 fj.07-9097comv3 22/1/64    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Endeward, V. Articles by Gros, G. PubMed PubMed Citation Articles by Endeward, V. Articles by Gros, G.

RhAG protein of the Rhesus complex is a CO₂ channel in the human red cell membrane

Volker Endeward^*, Jean-Pierre Cartron^,, Pierre Ripoche^, and Gerolf Gros^*,1

^* Abteilung Vegetative Physiologie, Medizinische Hochschule Hannover, Hannover, Germany;

Institut National de la Santé et de la Recherche Médicale, Paris, France; and

Institut National de la Transfusion Sanguine, Paris, France

¹Correspondence: Abt. Vegetative Physiologie Medizinische Hochschule Hannover, 30623-Hannover, Germany. E-mail: gros.gerolf{at}mh-hannover.de

We have determined CO₂ permeabilities, P_CO2, of red cells of normal human blood and of blood deficient in various blood group proteins by a previously described mass spectrometric technique. While P_CO2 of normal red cells is 0.15 cm/s, we find in red blood cells (RBCs) lacking the Rh protein complex (Rh_null) a significantly reduced P_CO2 of 0.07 cm/s ±0.02 cm/s (P<0.02). This value is similar to the value we have reported previously for RBCs lacking aquaporin-1 protein (AQP-1_null), suggesting that each of the Rh and AQP-1 proteins is responsible for 1/2 of the normal CO₂ permeability of the RBC membrane. Four other blood group deficiencies tested lack diverse membrane proteins but exhibit normal CO₂ permeability. The CO₂ pathway constituted by Rh proteins was inhibitable at pH_e= 7.4 by NH₄Cl with an I₅₀ of 10 mM corresponding to an I₅₀ for NH₃ of 0.3 mM. The pathway independent of Rh proteins, presumably that constituted by AQP-1, was not inhibitable by NH₄Cl/NH₃. However, both pathways were strongly inhibited by DIDS, which accounts for the marked inhibitory effect of DIDS on normal P_CO2, while in contrast another AE1 inhibitor, DiBAC, does not inhibit P_CO2, although it markedly reduces P_HCO3-. We conclude that Rh protein, presumably the Rh-associated glycoprotein RhAG, possesses a gas channel that allows passage of CO₂ in addition to NH₃.—Endeward, V., Cartron, J.-P., Ripoche, P., and Gros, G. RhAG protein of the Rhesus complex is a CO₂ channel in the human red cell membrane.

Key Words: Rhesus-associated glycoprotein • membrane CO₂ permeability • ammonia • aquaporin-1