DIETARY-FAT MODULATION OF LEFT-VENTRICULAR EJECTION FRACTION IN THE MARMOSET DUE TO ENHANCED FILLING

Objective: The aim was to investigate the influence of long term dietary fish oil consumption on cardiac function in a non-human primate, to elucidate further the basis of the apparently reduced cardiovascular disease mortality associated with its consumption in man. Methods: Adult male marmoset monkeys (Callithirix jacchus) were fed diets supplemented with polyunsaturated fatty acids (PUFA) of marine (tuna fish oil) or plant (sunflower seed oil) origin, saturated animal fat (sheep perirenal fat), or a low fat reference diet for 24 months. Cardiac function was assessed using radionuclide angiography under pentobarbitone anaesthesia with a counts based adaptation for ventricular volume estimations. Measures were made at rest and during infusion of adrenaline. Results: The mean left ventricular ejection fraction was greater in the tuna fish oil group 155.0(SEM 1.1)% n=7] and the sunflower seed oil group [58.1(2.4)% n=8] than in the reference group 148.5(1.4)% n=9] and the sheep fat group [47.6(1.8)% n=8]. This was associated with a more than 25% greater end diastolic volume and 40-70% increases in stroke volume in tuna fish or sunflower seed oil fed animals. There was no evidence of cardiac hypertrophy. In contrast, adrenaline increased stroke volume and ejection fraction by increasing emptying, thus reducing residual end systolic volume. Tuna fish oil fed animals had a low resting heart rate. When this was raised to comparable levels by adrenaline, lower pressure-rate indices and greater cardiac minute work suggested higher myocardial energy efficiency in PUFA fed animals compared with the reference and sheep fat groups. Conclusions: Dietary fish oil and sunflower seed oil increased the left ventricular ejection fraction in the marmoset monkey by enhancing ventricular filling, thus providing an energy sparing promotion of diastolic relaxation.