DIETARY-LIPID MODIFICATION OF MYOCARDIAL EICOSANOIDS FOLLOWING ISCHEMIA AND REPERFUSION IN THE RAT

Several different edible oils were compared for their ability to modif y eicosanoid biosynthesis following experimentally-induced myocardial ischemia and reperfusion in the rat. Two types of palm oil [neutralize d, bleached, and deodorized (NBDPO) and refined, bleached, and deodori zed (RBDPO)] and partially hydrogenated soybean oil (SBO) were tested against a diet supplemented with sunflower seed oil (SSO) rich in n-6 polyunsaturated fatty acids (PUFA). Fish oil (FO) rich in n-3 PUFA, wi th its known cardioprotective actions, served as an internal reference point for the study. Test oils were fed as a 12% (w/w) supplement for nine months before the induction of myocardial ischemia and reperfusi on. Palm oil diets exerted effects indistinguishable from the SBO grou p against cardiac arrhythmia, which occurred following alterations to coronary blood flow. Arrhythmic potentials, as expressed by a hierarch ical scale (0-9) of arrhythmia score, were: SSO, 1.5 +/- 0.5; FO, 0.9 +/- 0.4; SBO, 3.1 +/- 0.5; NBDPO, 3.2 +/- 0.5*; RBDPO, 3.3 +/- 0.6*; P < 0.05 vs. SSO. Following ischemia and reperfusion, both SSO and RB DPO groups tended to show an increase in myocardial prostacyclin, with the effect being more prominent in the RBDPO group (SSO, 10%; RBDPO, 25%). Thromboxane production was reduced in the FO group. Interestingl y, cardiac muscle from both FO and palm oil groups displayed a reduced capacity to produce 12-hydroxyeicosatetraenoic acid SSO, 591.9 +/- 95 .8; SBO, 375.5 +/- 48.9; NBDPO, 287.2 +/- 64.7; RBDPO, 230.9 +/- 80.2 *; FO, 203.7 +/- 81.4** (ng/g dry wt, *P < 0.05, **P < 0.01). No clea r relationship was seen between the availability of 20:4n-6 in myocard ial phospholipids and eicosanoid profile. Data suggests that fatty aci d composition of edible oils is not the only determinant of arrhythmic vulnerability and eicosanoid production.