Bay K 8644 is a negative inotrope in the presence of arachidonic acid but not eicosapentaenoic acid

Mitchell S. Finkel, Ryan C. Romeo, Theresa L. Hartsell, Carmine V. Oddis

Research output: Contribution to journalArticle

Abstract

The inotropic and radioligand binding characteristics of arachidonic acid (AA) and the fish oil derivative, eicosapentaenoic acid (EPA), were studied. AA alone was a concentration-dependent negative inotrope in isolated hamster papillary muscles. The negative inotropic effect of AA was enhanced 500-fold by the coadministration of indomethacin (cyclo-oxygenase inhibitor) and caffeic acid (lipoxygenase inhibitor). The dihydropyridine calcium channel agonist Bay K 8644 (BK) was a concentration-dependent positive inotrope. BK in the presence of AA was a concentration-dependent negative inotrope. The negative inotropic effect of BK in the presence of AA was blocked by caffeic acid but not indomethacin. EPA alone was a concentration-dependent negative inotrope. EPA had no effect on the positive inotropic effect of BK. Scatchard analyses of [3H]nitrendipine (dihydropyridine) binding to cardiac membranes in the presence of AA or EPA resulted in a decrease in the KD (-1/slope) with no effect on Bmax (x intercept). Kinetic studies further revealed that both AA and EPA enhanced the off rate of [3H]nitrendipine binding. These data suggest that both AA and EPA mediate similar direct negative inotropic effects through cardiac sarcolemmal calcium channels. A unique effect on E-C coupling by AA, not shared by EPA, is mediated through the lipoxygenase pathway (leukotrienes). AA and its eicosanoid products may play critically important roles in regulating myocardial contractility during acute and chronic myocardial ischemia. Differences between AA and EPA may contribute to the beneficial effects of dietary fish oils enriched in EPA.

Original languageEnglish (US)
Pages (from-to)563-571
Number of pages9
JournalJournal of Cardiovascular Pharmacology
Volume20
Issue number4
Publication statusPublished - 1992
Externally publishedYes

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Keywords

  • Arachidonic acid
  • Bay K 8644
  • Eicosapentaenoic acid
  • Inotropic effects

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Pharmacology

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