Age-dependency of vascular phospholipid deacylation-reacylation in spontaneously hypertensive rats

We have studied the temporal relation of phospholipid turnover and prostaglandin synthesis to the evolution of hypertensive vascular disease in the spontaneously hypertensive rat. The incorporation of arachidonate into aortic phospholipids, its release by phospholipase A2 and its utilization for prostaglandin synthesis were compared in spontaneously hypertensive and Wistar-Kyoto rats aged 7, 20 and 42 weeks. When expressed per mg of protein in the assay medium, arachidonate incorporation into aortic phospholipids decreased, while prostaglandin synthesis increased, with age in both rat strains. No significant differences were noted between hypertensive and normotensive animals at 7 weeks of age whereas both enhanced phospholipid turnover and prostaglandin synthesis was demonstrated in hypertensive rats at 20 and 42 weeks of age. The higher phospholipase activity in hypertensive aortas was associated with a significant increase in the capacity for exogenous lysophosphatide hydrolysis. Transacylation and reacylation of lysolecithin, however, were not significantly enhanced in hypertensive aortas. These biochemical changes accompany, and may be related to, structural modifications of the aortic wall in the course of hypertension.