Increased sympathetic innervation in the cerebral and mesenteric arteries of hypertensive rats

Abstract

The density of catecholamine-containing nerve fibers was studied in the cerebral and mesenteric arteries from normotensive Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke-prone SHR (SHRSP) in the growing (SHR, WKY) and adult (SHR, SHRSP, WKY) animals. Cerebral arteries from SHR showed an increased adrenergic innervation from day 1. The nerve plexuses reached an adult pattern earlier in SHR than in WKY. The arteries from adult SHR and SHRSP (22 weeks old) showed a markedly higher nerve density than WKY. There was a positive linear correlation between blood pressure and nerve density for four cerebral arteries. The mesenteric arteries were not innervated at birth. However, hyperinnervation of these arteries in the SHR was already present at 10 days of age as compared with WKY. Sympathectomy with anti-nerve growth factor and guanethidine caused a complete disappearance of fluorescent fibers in the mesenteric arteries from SHR and WKY, and in the cerebral arteries of WKY. The same procedure caused only partial denervation of the cerebral arteries from hypertensive animals. We postulate that the increase in nerve density in the cerebral arteries from the hypertensive rats may contribute to the development of arterial hypertrophy in chronic hypertension through the trophic effect of the sympathetic innervation on vascular structure.

Hypertension alters the function of nitrergic and sensory innervation in mesenteric arteries from female rats

“…Numerous studies have shown that increased sympathetic activity plays a role in the pathogenesis of hypertension [16,21,22]. Our results show that neither NA release nor the vasoconstrictor response to exogenous NA was modified by hypertension in female rats.…”

Angiotensin II Induces Media Hypertrophy and Hyperreactivity in Mesenteric but Not Epigastric Small Arteries of the Rat

“…In these rats, the levels of All are normal [35] while arteries are hyperinnervated [36,37], Besides neonatal sympathectomy [38], inhibitors of angiotensin-converting enzyme prevent small artery hypertrophy by a pressure-independent mechanism [31]. In general, experiments involving local surgical and systemic chemical or immunosympathectomy have indicated that sympathetic nerves exert a trophic influence in the young and stabilize arterial smooth mus cle cell contractile phenotype in the adult [39].…”

Augmented sensory‐motor vasodilatation of the rat mesenteric arterial bed after chronic infusion of the P1‐purinoceptor antagonist, DPSPX

“…These findings are in contrast to the enhanced tissue NA and enhanced sympathetic constrictor responses to EFS observed in tail arteries in the same DPSPX model of hypertension (Karoon et al, 1995). In the mesenteric vasculature of SHR there are conflicting reports of no change in the release of endogenous NA (Cline & Yamamoto, 1987) and elevated tissue NA and NPY content and augmented sympathetic neurotransmission (Scott & Pang, 1989;Longhurst et al, 1986;Lee et al, 1988;Heat, 1989;Mangiarua & Lee, 1989). Augmented sympathetic activity is a feature of other experimental models of hypertension and elevated plasma levels of NA have been reported in some patients with essential hypertension (De Champlain, 1990).…”