Interaction of iloprost and indomethacin with the cardiac effects of isoprenaline, ouabain and trapidil.

Investigations in isolated heart preparations of guinea pigs showed, that iloprost enhanced the increase of cardiac performance by isoprenaline, but inhibit the positive inotropic effect of ouabain. On the other side pretreatment with indomethacin induced a significant rise of the cardiac effects of both isoprenaline and ouabain. The efficacy of trapidil and oxyfedrine remained uninfluenced. The results indicate, that prostanoids and cyclooxygenase inhibitors influence the effects of the investigated cardiac drugs. This is possibly be due to changes in the cellular membrane and the intracellular calcium content and should be considered in the therapeutic use of these substances.