Comparison of the effects of BAY K 8644 on cardiac Ca2+ current and Ca2+ channel gating current

R. W. Hadley, W. J. Lederer

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Effects of (-)-BAY K 8644 on Ca2+ channel function were studied in guinea pig ventricular myocytes. It was found that the compound has both voltage-dependent stimulatory and inhibitory effects on the Ca2+ current (I(Ca)), in agreement with prior studies. The basis for these effects was studied by evaluating the effects of (-)-BAY K 8644 on the Ca2+ channel gating current. It was found that the voltage-dependent inhibitory effects of the drug on I(Ca) could be well explained by similar reductions in the amount of gating charge moved. However, the stimulatory effect of (-)-BAY K 8644 on I(Ca) could not be simply correlated with changes in the amount of gating charge moved. Although the drug produced a shift of the charge-voltage relationship to more negative potentials, the drug actually reduced the total amount of movable gating charge. Thus it could be demonstrated that there are membrane potentials where (-)-BAY K 8644 reduced the Ca2+ channel gating current while enhancing I(Ca). In addition, the drug was found to slow the decay of the gating current during repolarization. It seems likely that (-)- BAY K 8644 has a dual effect on Ca2+ channels: affecting both the voltage dependence of gating charge and the relationship between open probability and charge movement.

Original languageEnglish
Pages (from-to)H472-H477
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number2 31-2
StatePublished - 1992


  • calcium channel agonists
  • charge movement
  • dihydropyridines
  • heart

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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