Dietary polyunsaturated fatty acids alter myocardial protein kinase C expression and affect cardioprotection induced by chronic hypoxia
Abstract
The study of the influence of dietary fatty acid (FA) classes on the PKC delta and epsilon expression in relation to cardioprotective effects of chronic intermittent hypoxia. We examined the influence of dietary fatty acid (FA) classes on the expression of protein kinase C (PKC) delta and a in relation to the cardioprotective effects of chronic intermittent hypoxia (CIH).
Adult male Wistar rats were fed a nonfat diet enriched with 10% lard (saturated FA [SFA]), fish oil (n-3 polyunsaturated FA [n-3 PUFA]), or corn oil (n-6 PUFA) for 10 weeks. After 4 weeks on the diet, each group was divided into two subgroups that were either exposed to CIH in a barochamber (7000 m, 8 hrs/ day) or kept at normoxia for an additional 5-6 weeks.
A FA phospholipid profile and Western blot analysis of PKC were performed in left ventricles. Infarct size was assessed in anesthetized animals subjected to 20-min coronary artery occlusion and 3-hr reperfusion.
CIH decreased the n-6/n-3 PUFA ratio in all groups by 23% independently of the initial value set by various diets. The combination of n-3 diet and CIH had a stronger antiarrhythmic effect during reperfusion than the n-3 diet alone; this effect was less pronounced in rats fed the n-6 diet.
The normoxic n-6 group exhibited smaller infarctions (by 22%) than the n-3 group. CIH decreased the infarct size in n-3 and SFA groups (by 20% and 23%, respectively) but not in the n6 group.
Unlike PKC epsilon, the abundance of PKC delta in the myocardial particulate fraction was increased by CIH except for the n-6 group. Myocardial infarct size was negatively correlated (r = -0.79) with the abundance of PKC delta in the particulate fraction.
We conclude that lipid diets modify the infarct size-limiting effect of CIH by a mechanism that involves the PKC delta-dependent pathway.