ANTIHYPERTENSIVE EFFECT OF DIETARY DOCOSAHEXA-ENOIC ACID (22 6N-3) INSTROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS/

We previously reported that hypertension in stroke-prone spontaneously hypertensive rats (SHRSP) caused renal membrane phospholipid degradat ion. Renal phospholipase A(2) activity increased and membranous phosph olipids decreased with age in SHRSP. Membranous abnormalities induced by membrane fluidity and calcium permeability may contribute to the el evation of blood pressure in SHRSP. Docosahexa-enoic acid (DHA; 22: 6n -3) has a physiological effect on several important properties of biom embranes. The purpose of this study is to clarify the effect of DHA on the relationship between the renal function and the time-course of hy pertension in SHRSP. Six week-old male SHRSP were fed a semi-purified diet supplemented with DHA (0%, 1% and 5%) for 14 weeks. The systolic blood pressure of control SHRSP (DHA 0%) was significantly increased f rom 120.2 mmHg to 202.9 mmHg. This increase in systolic blood pressure was significantly inhibited in a dose-dependent manner in SHRSP that received DHA diet (1% and 5%) io 167.8 mmHg and to 149.8 mmHg, respect ively. Serum creatinine concentration and blood urea nitrogen were sig nificantly decreased in DHA (5%)-treated SHRSP as compared to those of the control SHRSP. Renal dope decarboxylase activity of the control S HRSP was significantly decreased as compared to that of WKY. In DHA (5 %)-treated SHRSP, dopa decarboxylase activity was increased and plasma dopamine concentration was intended to increase. An increase in dopam inergic tone was attributable to modulate sympathetic tone by DHA. The se results suggest that DHA may prevent lipid alteration, renal membra ne fluidity and prolong the time course of hypertension in SHRSP.