Possible Evidence for Transmembrane K+-H+ Exchange System inGuinea Pig Myocardium
| Autor: | Shozo Kanaya, Yasuo Tsuda, Takehiko Fujino, Toru Maruyama, Ryuichi Nagashima, Yoshiyuki Niho |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
medicine.medical_specialty
Patch-Clamp Techniques Intracellular pH Antiporter Guinea Pigs In Vitro Techniques Membrane Potentials Guinea pig H(+)-K(+)-Exchanging ATPase Internal medicine medicine Animals Homeostasis Myocyte Patch clamp Ion transporter Membrane potential Ion Transport Chemistry Myocardium Cell Membrane Hydrogen-Ion Concentration Molecular biology Endocrinology Potassium Cardiology and Cardiovascular Medicine Omeprazole |
| Zdroj: | Japanese Heart Journal. 40:351-364 |
| ISSN: | 1348-673X 0021-4868 |
| Popis: | 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 (ICa) 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 ICa. In conclusion, these data provide functional evidence for a myocardial transmembrane K(+)-H+ exchanger. |
| Databáze: | OpenAIRE |
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