Influences of dietary fats on coronary flow rate and left ventricular work of the isolated rat heart: sunflower seed oil versus lard.

The influences of dietary sunflower seed oil and lard on coronary flow rate and external left ventricular work were studied in the isolated Langendorff-perfused and working rat heart. For 1, 4 or 6 weeks, rats were fed diets containing 25--50% of the total digestible energy as fat, 23% as casein an 52--27% as starch. The coronary flow rate and the maximum left ventricular work of hearts of rats fed sunflower seed oil were higher than those of hearts of rats fed lard (about 15 and 10%, respectively). The maximum left ventricular work was achieved at a left ventricular filling pressure of 10--12 mm Hg: this value was not affected by the type of dietary fat. The effect of dietary fat on coronary flow rare is already seen after 1 week of feeding, and on left ventricular work after 4 weeks of feeding. Analysis of variance shows a positive relationship between the maximum left ventricular work and the amount of sunflower seed oil. It is concluded that dietary fats affect coronary flow rate and left ventricular work in the isolated rat heart. The increase in left ventricular work may be caused by an increase in contractility.