Possible evidence for transmembrane K+-H+ exchange system in guinea pig myocardium

Ryuichi Nagashima, Yasuo Tsuda, Toru Maruyama, Shozo Kanaya, Takehiko Fujino, Yoshiyuki Niho

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The aim of this study was to obtain evidence for a transmembrane K+-H+ exchange system in Langendorff-perfused whole hearts and isolated ventricular myocytes of guinea pig. Effluent relation between K+ and pH in the whole hearts perfused with HEPES-buffered Tyrode's solution indicated a significant (p < 0.05) functional coupling of K+ uptake and H+ extrusion that was energy-dependent and omeprazole (OPZ)-sensitive. Administration of OPZ (0.3 mM) or dimethylamiloride (0.1 mM), an inhibitor of Na+-H+ antiport, to whole hearts subjected to the repetitive NH4Cl applications implied that both Na+-H+ and putative K+-H+ countertransports contribute to the regulation of intracellular pH. In isolated myocytes, voltage-dependent L-type Ca current (I(Ca)) was inhibited by OPZ (0.3 mM) under K+- and Na+-free condition by 11 to 14%, and was inhibited to a greater extent (i.e., by 36 to 40%) by this agent in the presence of K+. OPZ-induced inhibition of the putative K+-H+ exchanger likely resulted in subsarcolemmal acidification which was responsible for the rate-independent suppression of I(Ca). In conclusion, these data provide functional evidence for a myocardial transmembrane K+-H+ exchanger.

Original languageEnglish
Pages (from-to)351-364
Number of pages14
Journaljapanese heart journal
Volume40
Issue number3
DOIs
Publication statusPublished - May 1 1999

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Omeprazole
Potassium-Hydrogen Antiporters
Myocardium
Guinea Pigs
Muscle Cells
HEPES
Ion Transport

All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine

Cite this

Possible evidence for transmembrane K+-H+ exchange system in guinea pig myocardium. / Nagashima, Ryuichi; Tsuda, Yasuo; Maruyama, Toru; Kanaya, Shozo; Fujino, Takehiko; Niho, Yoshiyuki.

In: japanese heart journal, Vol. 40, No. 3, 01.05.1999, p. 351-364.

Research output: Contribution to journalArticle

Nagashima, Ryuichi ; Tsuda, Yasuo ; Maruyama, Toru ; Kanaya, Shozo ; Fujino, Takehiko ; Niho, Yoshiyuki. / Possible evidence for transmembrane K+-H+ exchange system in guinea pig myocardium. In: japanese heart journal. 1999 ; Vol. 40, No. 3. pp. 351-364.
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