DECREASE IN VASODILATOR EFFECTS OF PLATELET-ACTIVATING-FACTOR IN RESISTANCE VESSELS OF SPONTANEOUSLY HYPERTENSIVE RATS

We studied the endothelium-dependent vasodilator effects of platelet-a ctivating factor (PAF) on the mesenteric arterial bed of Wistar Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) and found that vasodilation induced by PAF was significantly attenuated in SHRs. We d iscovered no significant differences in reactivity or sensitivity of t he mesentery to acetylcholine between WKYs and SHRs. Our results stron gly suggest that the attenuated vasodilator effects of PAF on the SHR mesenteric arterial bed may be due in part to desensitization rather t han impairment of the endothelium.