[The antihypertensive effect of saralasin in rabbits with neurogenic interoreceptive hypertension]

The renal nerve activity plays an essential role in the stimulation of plasma renin activity (PRA), which may be involved in the pathomechanism of neurogenic hypertension after sino-aortic denervation (SAD). Therefore, studies were conducted on unanesthetized rabbits (10 animals; 3-4 kg) after bilateral carotid sinus denervation plus section of cervical aortic nerves and the patterns of blood pressure (BP), heart rate (HR), and PRA were measured after a single injection-dosis of Saralasin (i.v., 10 micrograms/kg). After SAD the BP increased rapidly to 190 mm Hg within one week and remained at this high level (190-220 mm Hg) throughout the whole experiment (120 weeks). No change in BP of control rabbits (100-110 mm Hg) could be observed. Two weeks after SAD, the PRA showed a short elevation (approx. 25 ng) which subsequently returned to the levels of control rabbits (approx. 19 ng). Only in hypertensive rabbits Saralasin produced a short decrease of BP during both the initial and the whole chronic phases of hypertension, which was associated with a larger decrease of HR (1st to 5th min). Surprisingly, Saralasin induced a drop of HR also in the control rabbits. Our results suggest that also the normalized renin-angiotensin system is involved in the pathomechanism of sympathetic induced SAD-hypertension and probable permanently support the chronic state of hypertension by a relative "reninism".