Influence Of Dietary Linoleic-Acid On Cardiac-Function And Prostaglandin Release And On The Effects Of Isoprenaline In The Isolated Rat-Heart

We studied the effects of dietary linoleate on cardiac function and on the effectiveness of isoprenaline in isolated rat heart preparations. Male Wistar rats were fed either a diet rich in linoleic acid (LA) (25% of digestible energy as sunflower oil, 5% lard) or an LA-deficient diet (30% hydrogenated palm kernel oil). Control rats received a standard lab chow. Under certain experimental conditions the LA-rich diet resulted in increased contractile force, coronary flow rate, and prostaglandin (PG) release (PG-like substances and PGI2) and in a reduction in heart rate. These effects were modified by the duration of the feeding period and/or the age of the animals. In isolated perfused hearts of rats fed on a diet rich in LA for a 10-week period the inotropic effects of isoprenaline were diminished, whereas the isoprenaline-induced increase in coronary flow rate was augmented. The PG-releasing effect of isoprenaline was antagonized by the LA-rich diet. Preliminary in vivo investigations support these in vitro results. The mechanisms by which dietary LA influences cardiac function and the effectiveness of isoprenaline remain unclear.