Investigations on the mechanism of a diminished inotropic isoprenaline effect in isolated rat hearts after high linoleic acid diet.

Male Wistar rats were fed on a diet rich (13.3 J%) or poor (0.5 J%) in linoleic acid for 10 weeks. The inotropic and chronotropic effects of isoprenaline (100 ng) in isolated perfused hearts were reduced after a linoleic acid rich diet by 36% and 51%, respectively, with an accompanying reduction in isoprenaline-induced increase in the ventricular cAMP content. Moreover, the stimulation of adenylate cyclase in homogenates of ventricular tissue was diminished after linoleic acid rich diet. We postulate that the diminished adrenergic cardiac response after high vs. low linoleic acid diets could be due to alterations in the adenylate cyclase activity and cAMP formation.