New method for imaging innervation of the renal preglomerular vasculature.Alterations in hypertensive rats

Objective: To develop a new method for viewing adrenergic innervation along renal preglomerular vessels; to assess nerve densities and vascular lesion s along arcuate arteries (ArcA), arcuate arterial branches (ArcB), and inte rlobular arteries (ILA) in spontaneously hypertensive rats (SHR) and in ang iotensin II (Ang II) and in N-G-nitro-L-arginine methyl ester (L-NAME) hype rtensive rats. Methods: Preglomerular vasculatures mere isolated after HCl maceration and mere immunostained against synaptophysin, a membrane protein of synaptic ve sicles. Lesions were stained with Sudan black. Longitudinal nerve densities and relative frequencies of ArcA, ArcB, and ILA endowed with sudanophilic lesions mere assessed separately. Results: Synaptophysin immunostaining revealed the vascular neural plexus. Nerves mere adrenergic, as the plexus was destroyed by treatment with 6-hyd roxy dopamine. Vascular lesions were not seen in SHR, and increased nerve d ensity was observed along ArcA and ILA. In L-NAME- and AngII-hypertensive r ats, vascular lesions affected predominantly ArcB and ILA, and nerve densit y was reduced by 12% and 28% (ArcA), 37% and 31% (ArcB), and by 55% and 34% (ILA), respectively, versus normotensive controls. Endothelin-1 receptor b lockade did not affect AngII-induced hypertension but prevented both lesion development and reduction of density of the vascular neural plexus. Conclusions: The method me have devised provides a direct en face view of t he vascular adrenergic innervation of isolated preglomerular vasculature. M easurements in hypertensive rat models suggest a link between vascular lesi ons and reduction in nerve density in hypertension. Endothelin-1 likely pla ys a kev role in mediating both vascular injury and altered vascular nerve density in hypertension.