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This Article 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 Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Matchkov, V. V. Articles by Aalkjaer, C. PubMed Articles by Matchkov, V. V. Articles by Aalkjaer, C.

Na⁺/K⁺-pump modulates intercellular communication via interaction with other membrane transporters in vascular smooth muscle cells.

Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Alle 1160, Aarhus, DK-8000, Denmark

ABSTRACT

Ouabain, an inhibitor of the Na⁺/K⁺-pump, has previously been shown to disturb intercellular communication. Here we test the hypothesis that the communication between vascular smooth muscle cells (SMCs) is regulated through an interaction between the Na⁺/K⁺-pump and the Na⁺/Ca²⁺-exchanger in restricted spaces near the plasma membrane.

The intracellular Ca²⁺ concentration ([Ca²⁺]_i) in individual SMCs was imaged simultaneously with isometric force in rat mesenteric small arteries. Paired cultured rat aortic smooth muscle cells (A7r5) were used as a model for electrical coupling of SMC by measuring membrane capacitance (Cm).

SMCs were uncoupled (evaluated by inhibition of vasomotion and desynchronization of [Ca²⁺]_i transients in vascular wall, or by reduction of Cm measured in electrically coupled A7r5 cells) when the Na⁺/K⁺-pump was inhibited either by a low concentration of ouabain (1–10 µM) or by ATP depletion. Reduction of Na⁺/K⁺-pump activity by removal of extracellular K⁺ also uncoupled cells, but only after inhibition of K_ATP channels. Inhibition of the Na⁺/Ca²⁺-exchange activity by SEA0400 or by lowering the extracellular Na⁺ concentration also uncoupled the cells. Depletion of [Na⁺]_i and clamping low [Ca²⁺]_i prevented the uncoupling. The experiments suggest that the Na⁺/K⁺-pump may affect gap junction conductivity via localized changes in [Ca²⁺]_i through modulation of Na⁺/Ca²⁺-exchanger activity.

This Article 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 Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Matchkov, V. V. Articles by Aalkjaer, C. PubMed Articles by Matchkov, V. V. Articles by Aalkjaer, C.