Nervous Kidney

Abstract

Abstract-Increases in renal sympathetic nerve activity regulate the functions of the nephron, the vasculature, and the renin-containing juxtaglomerular granular cells. Because increased activity of the renin-angiotensin system can also influence nephron and vascular function, it is important to understand the interactions between the renal sympathetic nerves and the renin-angiotensin system in the control of renal function. These interactions can be intrarenal, for example, the direct (by specific innervation) and indirect (by angiotensin II) contributions of increased renal sympathetic nerve activity to the regulation of renal function. The effects of increased renal sympathetic nerve activity on renal function are attenuated when the activity of the renin-angiotensin system is suppressed or antagonized with ACE inhibitors or angiotensin II-type AT 1 -receptor antagonists. The effects of intrarenal administration of angiotensin II are attenuated after renal denervation. These interactions can also be extrarenal, for example, in the central nervous system, wherein renal sympathetic nerve activity and its arterial baroreflex control are modulated by changes in activity of the renin-angiotensin system. In addition to the circumventricular organs, whose permeable blood-brain barrier permits interactions with circulating angiotensin II, there are interactions at sites behind the blood-brain barrier that depend on the influence of local angiotensin II. The responses to central administration of angiotensin II-type AT 1 -receptor antagonists into the ventricular system or microinjected into the rostral ventrolateral medulla are modulated by changes in activity of the renin-angiotensin system produced by physiological changes in dietary sodium intake. Similar modulation is observed in pathophysiological models wherein activity of both the renin-angiotensin and sympathetic nervous systems is increased (eg, congestive heart failure). Thus, both renal and extrarenal sites of interaction between the renin-angiotensin system and renal sympathetic nerve activity are involved in influencing the neural control of renal function. (Hypertension. 2000;36:1083-1088.)Key Words: renin-angiotensin system Ⅲ renal nerves Ⅲ rats T he renal sympathetic nerves innervate the tubules, the vessels, and the juxtaglomerular granular cells of the kidney. 1,2 In this way, changes in renal sympathetic nerve activity (RSNA) directly influence the functions of these innervated renal effector units. Increases in RSNA decrease urinary sodium and water excretion by increasing renal tubular water and sodium reabsorption throughout the nephron, decrease renal blood flow and glomerular filtration rate by constricting the renal vasculature, and increase activity of the renin-angiotensin system (angiotensin [Ang]II) by stimulating renin release from juxtaglomerular granular cells. Ang II, through direct actions on Ang II-type AT 1 receptors located on tubular and vascular segments, can also increase renal tubular sodium, chloride, and water reabsorption an...

Decreased cardiac output, venous congestion and the association with renal impairment in patients with cardiac dysfunction

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Muscimol microinjection into cerebellar fastigial nucleus exacerbates stress-induced gastric mucosal damage in rats

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Nicousamide normalizes renovascular hypertension in two-kidney one-clip hypertensive rats

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