Central and peripheral contributions of the renin-angiotensin system in two models of experimental hypertension in rats.

To examine the relationships between the central and peripheral renin angiotensin system in normotensive Wistar Kyoto (WKY) rats, two-kidney, one-clip Goldblatt renovascular hypertension (RVH), spontaneously hypertensive rats (SHR), SQ 14225 (captopril) was administered intraventricularly (IVT) and intravenously (IV) in the alternative manner and their combination. Also, the effects of IVT captopril on the peripheral sympathetic nervous system were evaluated using an intravenous injection of prazosin. IVT captopril induced a significant reduction of blood pressure in both types hypertensive rats but not in normotensive rats. Greater depressor effects of IV captopril not IV prazosin following IVT captopril were observed in RVH compared to those in SHR. These results indicate that the pressor action of the brain renin angiotensin system is closely related with the sympathetic nervous system in hypertensive conditions and that these functions are independent from the peripheral renin angiotensin system. Furthermore, their roles were different in different types of experimental hypertension in rats.