[The importance of increased prostaglandins and prostacyclin for the effect of oxyfedrin in isolated guinea pig heart preparations]. / Zur Bedeutung einer vermehrten Freisetzung von Prostaglandinen und Prostazyklin für die Wirksamkeit von Oxyfedrin an isolierten Herzpräparaten des Meerschweinchens.

ABSTRACT

In isolated perfused heart preparations of guinea pigs coronary dilating and positive inotropic doses of oxyfedrine induce a significant increase of the release of prostaglandin-like substances (PLS) and prostacyclin (PGI2). Indometacin as an inhibitor of prostaglandin biosynthesis (140 mumol/l) enhances after a 10 min lasting perfusion contraction force and coronary flow of the hearts but inhibits PGI2-formation. Under these conditions oxyfedrine loses its positive influence on inotropism, coronary flow and PGI2-efflux. Indometacin (140 mumol/l) also completely abolishes the increase of cardiac performance of isolated auricle preparations by oxyfedrine (50 mumol/l). These findings agree with former results and indicate an involvement of the PLS- and PGI2-biosynthesis in the antianginal efficacy of oxyfedrine.