Influence of prostaglandins, prostaglandin-precursors and of a linoleic acid rich and free diet on the cardiac effects of isoprenaline and vasodilators.

In isolated auricle preparations of guinea pigs arachidonic acid diminished the increase in cardiac performance by isoprenaline in a similar way as PGE1 and propranolol. Long term pretreatment of rats with a linoleic acid (LA) supplemented diet increased in vivo the maximal systolic pressure and decreased the heart rate. In hearts in vitro the LA rich diet decreased the heart rate, increased the coronary flow and showed a tendency to enhance the contraction force. The release of cardiac prostaglandin-like substances was increased. Simultaneously the LA rich diet reduced the heart rate increase and the positive inotropic effect of isoprenaline without changing the increase in the coronary flow and without any effect on the heart performance of coronary vasodilators like oxyfedrine and prenylamine.