Radionuclide angiographic study of the influence of dietary lipid supplements on cardiac function in the marmoset (Callithrix jacchus).

Radionuclide angiography was used to examine the influence of dietary fat on cardiac function in the common marmoset monkey (Callithrix jacchus jacchus) under barbiturate anaesthesia. Animals were fed for 6-8 months with a low fat (4.5%) reference diet or the same diet supplemented (12%) with sunflower seed oil or sheep fat. Although there was a tendency towards increased heart rate, left ventricular ejection fraction, peak ejection rate, and peak filling rate in both fat supplemented groups, significant increases in heart rate (+50%), peak ejection rate (+71%), and peak filling rate (+84%) were found with sheep fat supplementation, whereas only the vegetable oil supplement produced a significant improvement in left ventricular ejection fraction (+23%). There were no differences in resting blood pressure, and the main consequence of dietary fat supplementation was a major increase in apparent cardiac oxygen consumption (+58%) with the sheet fat diet, as determined by the pressure-rate index. Infusion of isoprenaline hydrochloride (0.2 microgram.kg-1.min-1) increased all indices of cardiac function towards common maxima. There were no differences in either the depth or duration of anaesthesia between dietary groups. It therefore is unlikely that this contributed to any of the observed dietary induced differences in cardiac function. It is suggested that dietary saturated animal fat increased cardiac work and oxygen consumption at rest to the extent that functional reserve to respond to stress was significantly diminished. Feeding a linoleic acid rich polyunsaturated vegetable oil supplement was, however, accompanied by evidence of some improvement in left ventricular ejection fraction.