Renal nerves affect rate of achieving sodium balance in spontaneously hypertensive rats.

Abstract

The spontaneously hypertensive rat (SHR) has an elevated efferent sympathetic nerve activity, suggesting that the renal handling of sodium and water may be altered. This study evaluated the renal neurogenic influence on the rate of achieving sodium balance in adult SHRs and Wistar-Kyoto (WKY) rats after either a step increase or step decrease in fixed sodium intake. Conscious, unrestrained rats with either innervated or denervated kidneys were initially placed on a low-sodium (0.3 mEq/d) or high-sodium (5.0 mEq/d) intake by intravenous infusion. Hourly urinary sodium excretion was determined 24 hours before and 72 hours after sodium intake had been increased from low to high or decreased from high to low. After either step change in fixed sodium intake, both innervated SHRs and innervated WKY rats achieved sodium balance within 24 hours. Similarly, the time course of achieving sodium balance was nearly identical between WKY rats with innervated and denervated kidneys after either switch in sodium intake. In SHRs receiving a step increase in sodium intake, both innervated and denervated kidneys increased urinary sodium excretion equally for 9 hours; however, at this time, innervated SHRs continued to increase sodium excretion rapidly, whereas denervated rats were delayed in a further response. Thus, innervated SHRs achieved sodium balance approximately 18 hours sooner than denervated SHRs. Differences in urinary sodium excretion did not result from concomitant changes in plasma renin activity or mean arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Salt sensitivity of renin secretion, glomerular filtration rate and blood pressure in conscious Sprague‐Dawley rats

“…The present results show that new steady states were actually approached after 24 h, much in accordance with previous data (DiBona & Sawin , Greenberg et al . ). The linear relationship between plasma renin and the logarithm of sodium intake persisted throughout the range of sodium intakes, that is, the renin function curve is log‐linear over a large range of sodium inputs.…”

“…(Greenberg et al . , Shao et al . )] at a time when urinary levels of angiotensinogen and AngII are unchanged (Shao et al .…”

“…Years ago, it was concluded that in rats the renal nerves are required for the maintenance of sodium balance during dietary sodium restriction (DiBona & Sawin ), but the interaction between sodium balance, blood pressure and renin secretion during sodium restriction is complex (Greenberg et al . , Greenberg & Osborn , Machura et al . , Neubauer et al .…”

The role of the peripheral sympathetic nervous system in the natriuresis following central administration of an I1 imidazoline agonist, moxonidine

“…Animals were Bridsh Joumal of PhamscobW (1995) Symnpateic nervous systm and moxonidin housed at 23"C with 12 h light/12 h dark cycle. Denervation or sham-denervation of the renal sympathetic nerves to the left kidney was carried out during ether anaesthesia (see below) in animals weighing 180-220 g as previously described (Fortin & Sundaresan, 1989;Greenberg et al, 1993). Three days later, the right kidney was removed under ether anaesthesia as previously described (Penner & Smyth, 1994).…”

“…Denervation was performed in a similar manner to the protocol followed by Greenberg et al (1993). The kidney was exposed through a flank incision.…”