Effect of hypertension on lipid metabolism and beta-oxidation in rat aorta and brain microvessels.

The effects of hypertension on various enzyme activities involved in lipid metabolism and beta-oxidation in rat brain microvessels and aorta were studied. The purity of the brain microvessel preparation was confirmed immunologically and microscopically. Activities involved in lipid synthesis, such as triacylglycerol synthesizing activity, acyl-CoA synthesizing activity, acyl-CoA: cholesterol acyltransferase and cytidine diphosphate choline:1,2-diacylglycerol cholinephosphotransferase, were significantly higher in brain microvessels than in aorta in both normotensive and hypertensive rats; lipid hydrolyzing activities, such as lipases and cholesterol esterases, were similar in the two preparations. beta-oxidation in brain microvessels was more active than in aorta in both groups. Hypertension did not alter these enzyme activities in either aorta or brain microvessels, or change beta-oxidation in the aorta. However beta-oxidation in brain microvessels was significantly lower in hypertensive rats than in normotensive rats. These results suggest that brain microvessels are metabolically more active than aorta, and that their beta-oxidation activity is more susceptible to effects of hypertension. Reduced beta-oxidation in brain microvessels might lead to angionecrosis by derangement of energy production, which in turn may cause cerebral bleeding.