INFLUENCE OF TYPE OF DIETARY-FAT ON THE PROSTAGLANDIN RELEASE FROM ISOLATED RABBIT AND RAT HEARTS AND FROM RAT AORTAS

It has previously been found (1) that feeding rats a diet containing a high amount of sunflowerseed oil results in a higher coronary flow and left ventricular work of their isolated hearts as compared to hearts of rats fed hydrogenated coconut oil or lard. It was hypothesized that this phenomenon can be explained by an influence of dietary linoleic acid on prostaglandin synthesis in the heart. To verify this hypothesis rabbits and rats were fed for four weeks sunflowerseed oil (SSO), hydrogenated coconut oil (HCO) or lard (L) to a maximum of 30 to 40 per cent of the total digestable energy, and the prostaglandin release from the isolated perfused hearts and rat aortas was determined by gas chromatography and bio-assay (PGI2). For the isolated hearts of rabbits fed SSO, the release of PGE2, PGF2α and 6-oxo-PGF1α was 1.7, 0.7 and 3.0 ng min-1 g-1 dry weight respectively; when fed L, these values were 2.9, 1.1 and 5.6 ng min-1 g-1. For the isolated hearts of rats fed SSO, HCO or L, the total release of PGE2, PGD2, PGF2α and thromboxane B2 (TXB2) was 5.9, 5.8 and 5.6 ng min-1 g-1 respectively; the release of 6-oxo-PGF1α was 3.4, 5.7 and 6.4 ng min-1 g-1 respectively. Relatively, 26% PGE2, 13% PGD2, 8% PGF2α, 6% TXB2 and 47% 6-oxo-PGF1α were released. For the isolated aortas of rats fed SSO or HCO, the release of PGI2-like activity was 0.37 ± 0.05 and 0.49 ± 0.05 ng min-1 cm-2. The release of PGI2-like activity from hearts of EFA-deficient rats was about 20% of that from control hearts. We conclude that, although feeding sunflowerseed oil, with respect to feeding hydrogenated coconut oil or lard, does increase coronary flow and left ventricular work, it does not increase the basal prostaglandin production in the isolated rat or rabbit heart; instead there is a tendency for a lower PGI2 synthesis. © 1979.