Abstract
The arterial baroreceptor reflex system is one of the most powerful and rapidly acting mechanisms for controlling arterial pressure. The purpose of the present review is to discuss data relating sympathetic activity to the baroreflex control of arterial pressure in two different experimental models: neurogenic hypertension by sinoaortic denervation (SAD) and high-renin hypertension by total aortic ligation between the renal arteries in the rat. SAD depresses baroreflex regulation of renal sympathetic activity in both the acute and chronic phases. However, increased sympathetic activity (100%) was found only in the acute phase of sinoaortic denervation. In the chronic phase of SAD average discharge normalized but the pattern of discharges was different from that found in controls. High-renin hypertensive rats showed overactivity of the renin angiotensin system and a great depression of the baroreflexes, comparable to the depression observed in chronic sinoaortic denervated rats. However, there were no differences in the average tonic sympathetic activity or changes in the pattern of discharges in high-renin rats. We suggest that the difference in the pattern of discharges may contribute to the increase in arterial pressure lability observed in chronic sinoaortic denervated rats.
Highlights
The arterial baroreceptor reflex system is one of the most powerful and rapidly acting mechanisms for controlling arterial pressure (AP)
Studies performed in experimental animals and in humans have documented that high blood pressure markedly impairs baroreceptor control of heart rate (HR) [4]
The purpose of the present review is to provide evidence concerning the role of the autonomic nervous system in arterial pressure control in two different models: neurogenic hypertension produced by sinoaortic denervation and high-renin hypertension produced by total aortic ligation between the renal arteries
Summary
Symposium on Vasoactive Peptides, Ouro Preto, MG, Brasil, October 6-8, 1997. Research supported by FINEP, FAPERGS, FAPESP and FEJZ. The purpose of the present review is to discuss data relating sympathetic activity to the baroreflex control of arterial pressure in two different experimental models: neurogenic hypertension by sinoaortic denervation (SAD) and high-renin hypertension by total aortic ligation between the renal arteries in the rat. SAD depresses baroreflex regulation of renal sympathetic activity in both the acute and chronic phases. In the chronic phase of SAD average discharge normalized but the pattern of discharges was different from that found in controls. There were no differences in the average tonic sympathetic activity or changes in the pattern of discharges in high-renin rats. We suggest that the difference in the pattern of discharges may contribute to the increase in arterial pressure lability observed in chronic sinoaortic denervated rats
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