Altered urinary sodium excretion response after central cholinergic and adrenergic stimulation of adult spontaneously hypertensive rats

Abstract

In this study, we hypothesized that blunting of the natriuresis response to intracerebroventricularly (i.c.v.) microinjected cholinergic and adrenergic agonists is involved in the development of hypertension in spontaneously hypertensive rats (SHR). We evaluated the effect of i.c.v. injection of cholinergic and noradrenergic agonists, at increasing concentrations, and of muscarinic cholinergic and α1 and α2-adrenoceptor antagonists on blood pressure and urinary sodium handling in SHR, compared with age-matched Wistar Kyoto rats (WR). We confirmed that CCh and NE microinjected into the lateral ventricle (LV) of conscious rats leads to enhanced natriuresis. This response was associated with increased proximal and post-proximal sodium excretion accompanied by an unchanged rate of glomerular filtration. We showed that cholinergic-induced natriuresis in WR and SHR was attenuated by previous i.c.v. administration of atropine and was significantly lower in the hypertensive strain than in WR. In both groups the natriuretic effect of injection of noradrenaline into the LV was abolished by previous local injection of an α1-adrenoceptor antagonist (prazosin). Conversely, LV α2-adrenoceptor antagonist (yohimbine) administration potentiated the action of noradrenaline. The LV yohimbine pretreatment normalized urinary sodium excretion in SHR compared with age-matched WR. In conclusion, these are, as far as we are aware, the first results showing the importance of interaction of central cholinergic and/or noradrenergic receptors in the pathogenesis of spontaneous hypertension. These experiments also provide good evidence of the existence of a central adrenergic mechanism consisting of α1 and α2-adrenoceptors which works antagonistically on regulation of renal sodium excretion.

Renal sodium handling and blood pressure changes in gestational protein-restricted offspring: Role of renal nerves and ganglia neurokinin expression

“…These effects are independent of changes in renal hemodynamics [46,49]. Taken together with previous findings [10,25,28,30,50,51], the current study demonstrated that bilateral renal denervation delays the development of arterial hypertension associated with reduced sodium reabsorption by the proximal and/or post-proximal tubule segments in this particular experimental model of developmental programming.…”

“…Inc, MA, USA), respectively. Thereafter, animals were anaesthetized with ketamine and xylazine injected intraperitoneally and sacrificed by cardiac puncture; urine and plasma samples were stored for analysis [3,4,6,7,29,30]. …”

“…Fractional sodium excretion (FE Na ) was calculated as C Na /C Cr ×100, where C Na is sodium clearance. Fractional proximal (FEP Na ) and post-proximal (FEPP Na ) sodium excretion were calculated as C Li /C Cr × 100 and C Na /C Li × 100, respectively [3,4,6,7,29,30]. Data obtained over time were analyzed using two-way ANOVA or nonparametric analysis using the Kruskal–Wallis test.…”

Impact of gestational low-protein intake on embryonic kidney microRNA expression and in the nephron progenitor cells of the male offspring fetus

“…Animal and Diets -The experiments were conducted as described in detail previously (Lutaif et al, 2015) on an age-matched female and male rats of sibling-mated Wistar HanUnib rats (250-300 g) that were allowed free access to water and standard rodent chow (Nuvital, Curitiba, PR, Brazil).…”

Effect of intracerebroventricular epinephrine microinjection on blood pressure and urinary sodium handling in gestational protein-restricted rat adult male offspring

“…It has long been known that there is an association between the CNS and the control of water and salt excretion by the kidneys [1,13,14]. Adrenergic stimulation of the septal area, lateral hypothalamus, subfornical organ, and the anterior region of the third ventricle induces dose-related natriuresis accompanied by, but to a lesser extent, kaliuresis [9,[15][16][17][18][19][20][21]. On the other hand, studies have shown that electrolytic lesion of the hypothalamic regions in conscious rats reduces salt intake, and the pressor response to cholinergic and noradrenergic microinjection into the median preoptic nucleus [22].…”