Phosphatidylinositol hydrolysis is involved in production of Ca(2+)-dependent currents, but not non-selective cation currents, by muscarine in chromaffin cells

European Journal of Pharmacology
M InoueI Imanaga

Abstract

Whether phosphatidylinositol hydrolysis and a subsequent Ca2+ mobilization are responsible for muscarine-induced transient outward currents (IO) and non-selective cation currents (INS) in the guinea-pig chromaffin cell was investigated using the perforated patch method. IO, but not INS, failed to be reproduced in Ca(2+)-free solution and was markedly reduced by prior exposure to caffeine under Ca(2+)-free conditions or by addition to normal solution of cyclopiazonic acid (CPA), a Ca2+ ATPase inhibitor. Application of CPA in Ca(2+)-free solution, however, suppressed INS by about 50% in 73% of the cells tested. Bath application of 1.5 mM neomycin, a phospholipase C inhibitor, induced the time-dependent decline of IO with near abolition at 20 min or less, whereas it produced a time-independent decrease of INS and an inwardly rectifying K+ current. INS in the presence or absence of neomycin was well fitted to rectangular hyperbolas with the same ED50 of 2.17 microM, but with a 33% smaller maximum amplitude in the former, indicating a non-competitive inhibition by neomycin. We conclude that, while phosphatidylinositol hydrolysis mediates the production of IO, it does not mediate that of INS by muscarine.

References

Jan 1, 1990·The Japanese Journal of Physiology·M Inoue, H Kuriyama
May 9, 1988·Biochimica Et Biophysica Acta·M Gustin, T M Hennessey
Aug 1, 1988·The Journal of General Physiology·R Horn, A Marty
Apr 15, 1988·Biochemical and Biophysical Research Communications·M IinoM Endo
Sep 1, 1982·Pflügers Archiv : European journal of physiology·N HinoT Yanagisawa
Aug 1, 1993·The American Journal of Physiology·M Inoue, I Imanaga
Oct 1, 1993·The American Journal of Physiology·M Inoue, I Imanaga

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Citations

Jan 16, 2003·Cell Calcium·Masumi InoueAkira Warashina
Nov 21, 1998·The European Journal of Neuroscience·J G BarbaraK Takeda
Nov 4, 2006·The Journal of Physiological Sciences : JPS·Yutaka EndoMasumi Inoue
Aug 6, 2002·The Journal of Biological Chemistry·Jean-François RollandPatrick Gilon
Feb 12, 1998·The American Journal of Physiology·M Inoue, I Imanaga

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