Changes of plasma renin activity following intracerebroventricular administration of biologically active peptides in two-kidney, one clip hypertensive rats

We studied the effects of intracerebroventricular (ICV) administration of angiotensin II (ANG II), bradykinin (BK), leucine-enkephalin (Leu-ENK) and neurotensin (NT) on plasma renin activity (PRA), blood pressure and heart rate in acute (less than 4 weeks) and chronic (more than 12 weeks) two-kidney, one clip (2K-1C) hypertensive rats. These four peptides all produced pressor responses. The pressor responses caused by ICV injection of ANG II, BK, Leu-ENK and NT in hypertensive rats did not differ significantly from the response in normal rats. In both acute and chronic 2K-1C hypertensive rats, ANG II and BK significantly suppressed PRA, NT did not affect PRA, and Leu-ENK produced a significant increase in PRA followed by a significant decrease in PRA. As compared to normal rats, suppression of PRA by ANG II and NT was attenuated or abolished but BK and Leu-ENK produced significant reductions in PRA in 2K-1C hypertensive rats. The results indicate that the effects of these four centrally administered peptides on blood pressure, heart rate and PRA in acute and chronic 2K-1C hypertensive rats were not essentially different from those in normal rats.