Dietary lipid modulation of myocardial beta-adrenergic mechanisms, Ca2+-dependent automaticity, and arrhythmogenesis in the marmoset.

Dietary lipid supplements high in either saturated fatty acids derived from sheep perirenal fat or polyunsaturated fatty acids (65% linoleic acid) derived from sunflower seed oil were fed to marmoset monkeys (Callithrix jacchus) for 20 months. The effect of these long-term dietary lipid supplements on myocardial contractile function and their influence on responses to isoprenaline and external calcium concentration were examined using isolated papillary muscles and atria. Isoprenaline potency was increased by the sheep fat-supplemented diet, which induced significant three- to eightfold leftward parallel shifts of isoprenaline dose-response curves for papillary muscle and left atrial inotropy and right atrial chronotropy. The antagonist potency of propranolol was not influenced by diet. The incidence of isoprenaline-induced spontaneous tachyarrhythmias in electrically driven papillary muscles and left atria was reduced by the sunflower seed oil-supplemented diet and increased by the sheep fat diet, as were the spontaneous beat rate and calcium-dependent automaticity of right atria. These results show that dietary lipids can significantly modify stimulus-response coupling and alter the susceptibility to arrhythmogenesis in the heart of the nonhuman primate, and indicate that nutritional interventions may modify responses to cardioactive drugs as well as influence the development of cardiac disease.