Influence of dietary rapeseed oil and erucic acid upon myocardial performance and hemodynamics in rats.

Rats fed rapeseed oil, pure erucic acid, or a control diet of sunflowerseed oil during 24-26 weeks were studied for effects upon mechanical behavior of the isolated perfused heart and upon myocardial performance and hemodynamics in intact animals both under basal and stimulated conditions. In spite of focal myocardial fibrotic lesions due to rapeseed oil, no changes were found with respect to the intrinsic myocardial contractility in vitro and and in vivo. After inotropic intervention, only the rapeseed oil fed animals showed less contractile reserve capacity. The absence of this effect in the erucic acid-treated animals is in agreement with the histological studies showing no epicardiac fibrotic lesions in these animals. It appears that erucic acid is able to interfere with the contractile system of the peripheral vascular system. Both in the rapeseed oil-treated group and the erucic acid-treated group, the vasoconstrictor response toward norepinephrine was profoundly reduced. In all three oil fed groups, isoproterenol reduced myocardial contractility which has been attributed to a lowered perfusion pressure in the coronary blood supply of the myocardium with simultaneous increased energy demand. Neither rapeseed oil nor erucic acid feeding led to electrocardiographic changes in comparison with the control sunflowerseed oil group. It is concluded that rapeseed oil and not erucic acid is responsible for loss of contractile reserve capacity without changes in the myocardial conductance system and further, that erucic acid might interfere with the peripheral vascular system. Finally, it appears that a fat rich diet might result in reduced myocardial function during a state of energy demand coupled with a blood pressure decrease.