Cytoplasmic pH regulates ATP-induced Ca(2+)-dependent K(+)-current oscillation in rat megakaryocytes.
The effect of cytoplasmic pH (pH(i)) on ATP-induced Ca2+ oscillation of rat megakaryocytes was investigated by the whole-cell patch-clamp technique. Megakaryocytes responded to extracellular ATP and showed the periodic activation of K+ channels, which reflects the oscillation in intracellular free Ca2+ concentration. Intracellular alkalinization by 20 mM NH4Cl resulted in inhibition of the oscillatory response, and intracellular acidification by 20 mM sodium acetate enhanced the response. NH4Cl also inhibited the Ins(1,4,5)P3-induced oscillation. Sodium acetate had no effect on the InsP3-induced oscillation, but enhanced the guanosine 5'-[gamma-thio]triphosphate-induced response. These results indicate that pH(i) modulates the ATP-induced cellular response at least at two points.
Uneyama
C
C
Division of Pathology, National Institute of Health Sciences, Tokyo, Japan.
Uneyama
H
H
Takahashi
M
M
Akaike
N
N
D000085:Acetates / Q000494:pharmacology; D019342:Acetic Acid; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004553:Electric Conductivity / Q000187:drug effects; D005260:Female; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007295:Inositol Phosphates / Q000494:pharmacology; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects / Q000378:metabolism*; D010507:Periodicity; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats
D000085:Acetates; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007295:Inositol Phosphates; D015221:Potassium Channels; D000643:Ammonium Chloride; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D000255:Adenosine Triphosphate; D019342:Acetic Acid; D002118:Calcium