Are Centrally Acting Imidazoline Agents Appropriate Therapy for Renovascular Hypertension?

Abstract

An increased role of the sympathetic nervous system has been suggested to be a major contributor to the chronic elevation of BP in renovascular hypertension. We assessed the effects of rilmenidine, a centrally acting antihypertensive imidazoline agent, on BP and renal sympathetic nerve activity (RSNA) in 2K1C renovascular hypertensive conscious rabbits. Rabbits were made hypertensive with a renal clip or were sham-operated and were studied 3 and 6 weeks later. Acute treatment with rilmenidine reduced BP to a greater extent in the hypertensive rabbits. Although rilmenidine reduced the heart rate by the same extent in all groups, rilmenidine produced much less inhibition of RSNA in the hypertensive animals. These studies suggest that the contribution of the sympathetic nervous system is greater in 2K1C hypertension and that imidazoline agents may be beneficial in treating renovascular hypertension.

Effects of chronic sympatho‐inhibition on reflex control of renal blood flow and plasma renin activity in renovascular hypertension

“…, 2009). Collectively, these findings support the view that inhibition of the SNS is an appropriate and effective treatment for renovascular hypertension (Head and Burke, 2003).…”

“…, 1996). Our own studies in both 2K1C hypertension and angiotensin II (Ang II) infusion hypertension using conscious rabbits showed that basal renal sympathetic nerve activity (RSNA) was well maintained (Head and Burke, 2003; 2004; Burke et al. , 2008; Burke and Head, 2009), and that the sympathetic responses to acute airjet stress were exaggerated in the hypertensive animals (Head and Burke, 2004).…”

Cardiac and renal baroreflex control during stress in conscious renovascular hypertensive rabbits: effect of rilmenidine

“…Furthermore, we have suggested that such sympatholytic agents are effective treatments for 2K1C hypertension and may be appropriate to reduce the impact of acute stress during hypertension on baroreflex function [23]. We therefore also determined, in the current study, the effect of both acute and chronic treatment with rilmenidine on the baroreflex control during acute airjet stress.…”

Effects of chronic sympatho-inhibition on renal excretory function in renovascular hypertension

“…For example, a recent study demonstrated that denervation of the kidney can normalize blood pressure in resistant hypertensive individuals [6]. There is also considerable evidence that sympathetic nerve activity is elevated in renovascular hypertension [7,8]. Pharmacotherapy of renovascular hypertension with sympatholytic agents appears to be effective [7].…”

“…There is also considerable evidence that sympathetic nerve activity is elevated in renovascular hypertension [7,8]. Pharmacotherapy of renovascular hypertension with sympatholytic agents appears to be effective [7]. Two such clinically used agents are rilmenidine and moxonidine, which act on imidazoline receptors and a2-adrenoceptors in the brainstem to lower sympathetic tone [9,10].…”