Attenuated depressor response to arachidonic acid and prostaglandins in unclipped renal hypertensive rats.

1 In renal hypertensive rats (one-clip, two-kidney type) blood pressure returned to a normotensive level within 24 h after the removal of the renal artery clip (unclipping). 2 The decrease in blood pressure caused by intravenous administration of arachidonic acid, prostaglandin E2 and prostaglandin I2 was significantly reduced in these unclipped rats. 3 The hypotensive response to bradykinin and acetylcholine was the same in unclipped rats and in control rats. 4 Nephrectomy abolished the difference in blood pressure response to arachidonic acid and the two prostaglandins between unclipped and control rats. 5 An enhanced secretion of renin, as indicated by the absence of an increase in plasma renin activity, did not seem to be involved in the attenuated blood pressure response to arachidonic acid in unclipped rats.