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Abstract
IntroductionThe present study tested the hypothesis that long-term effects of baroreceptor activation might contribute to the prevention of persistent arterial blood pressure (BP) increase in the rat model of renovascular hypertension (HTN).MethodsRepetitive arterial baroreflex (BR) testing was performed in normo- and hypertensive rats. The relationship between initial arterial BR sensitivity and severity of subsequently induced two-kidney one-clip (2K1C) renovascular HTN was studied in Wistar rats. Additionally, the time course of changes in systolic BP (SBP) and cardiac beat-to-beat (RR) interval was studied for 8 weeks after the induction of 2K1C renovascular HTN in the rats with and without sinoaortic denervation (SAD). In a separate experimental series, cervical sympathetic nerve activity (cSNA) was assessed in controls, 2K1C rats, WKY rats, and SHR.ResultsThe inverse correlation between arterial BR sensitivity and BP was observed in the hypertensive rats during repetitive arterial BR testing. The animals with greater initial arterial BR sensitivity developed lower BP values after renal artery clipping than those with lower initial arterial BR sensitivity. BP elevation during the first 8 weeks of renal artery clipping in 2K1C rats was associated with decreased sensitivity of arterial BR. Although SAD itself resulted only in greater BP variability but not in persistent BP rise, the subsequent renal artery clipping invariably resulted in the development of sustained HTN. The time to onset of HTN was found to be shorter in the rats with SAD than in those with intact baroreceptors. cSNA was significantly greater in the 2K1C rats than in controls.ConclusionsArterial BR appears to be an important mechanism of long-term regulation of BP, and is believed to be involved in the prevention of BP rise in the rat model of renovascular HTN.
Highlights
The present study tested the hypothesis that long-term effects of baroreceptor activation might contribute to the prevention of persistent arterial blood pressure (BP) increase in the rat model of renovascular hypertension (HTN)
The concept of BP self-regulation has been questioned by Guyton and colleagues, who suggested that long-term regulation of BP is ensured by the renal mechanisms, while the role of arterial baroreceptor reflex (BR) is limited to the buffering of acute BP changes [3,4,5,6]
Our pilot experiments have demonstrated that sinoaortic denervation with or without subsequent renal artery clipping resulted in high mortality rates in animals under 14 weeks of age
Summary
The present study tested the hypothesis that long-term effects of baroreceptor activation might contribute to the prevention of persistent arterial blood pressure (BP) increase in the rat model of renovascular hypertension (HTN). The role of arterial baroreceptor reflex (BR) in blood pressure (BP) regulation has been extensively studied for almost a century Numerous studies in this field led to the introduction of the concept of BP self-regulation in the late 50s [1,2]. Denervation of baroreceptors in the carotid sinus and aortic arch in different animal species was associated with only transient elevation of BP followed by its normalization within a few days [4,7,8,9] This fact does not necessarily imply that arterial BR is not involved in the long-term regulation of BP. This notion is supported by the findings of studies on dogs [11,12], which show that stable hypertension (HTN) can be induced only after denervation of all mechanoreceptive zones
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