Stimulation rate modulates effects of the dihydropyridine CGP 28 392 on cardiac calcium‐dependent action potentials

Timothy J. Kamp, Richard J. Miller, Michael C. Sanguinetti*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Calcium (Ca2+)‐dependent action potentials were recorded from 22 mM potassium (K+)‐depolarized guinea‐pig papillary muscle at several different pacing frequencies in the absence and presence of CGP 28 392 (10 μM), a Ca2+ channel agonist. The maximum upstroke velocity (max) of the slow response action potential was measured to determine relative changes in Ca2+ current as a function of pacing frequency. CGP 28 392 increased max more than two fold at low rates of stimulation (1 or 12 pulses min−1), but had no significant effect on max during rapid pulsing (200 pulses min−1). The enhancement of max was dependent upon extracellular [K+]. Increasing extracellular [K+] from 22 mM to 27 mM suppressed the frequency‐dependent agonist effects and increased the antagonist effects on max. These results indicate that CGP 28 392 is a partial Ca2+‐channel agonist and suggest that its effects on Ca2+ current are voltage‐dependent. 1985 British Pharmacological Society

Original languageEnglish (US)
Pages (from-to)523-528
Number of pages6
JournalBritish journal of pharmacology
Volume85
Issue number2
DOIs
StatePublished - Jun 1985

ASJC Scopus subject areas

  • Pharmacology

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