Changes in Prostanoid Synthesis in Response to Diet and Hypertension in One-Kidney, One Clip Rats

This study was designed to examine the effects of diets that alter prostaglandin biosyn-thesis on the blood pressure in one-kidney, one clip rats with established hypertension and to compare the prostanoid generating capacity of hypertensive animals with those that remained normotensive. Rats attaining blood pressures of at least 180 mm Hg within 8 weeks of nephrectomy and renal artery stenosis were paired by weight and blood pressure and then placed on either a safflower oil or a prostaglandin I2 inhibitory diet (cod liver oil-linseed oil mix) for 4 weeks. Animals with blood pressures of less than 150 mm Hg were also paired for the same two dietary regimens. Comparison between the two blood pressure groups revealed that on both dietary regimens hypertensive rats produced significantly more aortic 6-keto-prostaglandin Flα and serum thromboxane B2. Rats on the cod liver oil-linseed oil diet incorporated eicosapentaenoic acid into tissue stores with a corresponding decrease in arachidonic acid and significantly impaired ability to generate serum thromboxane B2 (36%), aortic 6-keto-prostaglandin Flα (65%), renal homogenate 6-keto-prostaglandin Flα (64%) and prostaglandin E2 (58%), and urinary prostaglandin E2 (70%) and 6-keto-prostaglandin Flα (52%). Despite these differences in prostanoid synthesizing capacity, no differences in blood pressure were observed between the safflower oil-fed rats and rats fed cod liver oil-linseed oil within either the hypertensive or normotensive groups. These results suggest that prostanoids do not play a major role in maintaining blood pressure in established one-kidney, one clip hypertension. However, there was enhanced synthesis of aortic prostacyclin and serum thromboxane B2 (in hypertensive rats by mecha-nisms yet to be ascertained.