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NO-mediated signal transmission in bladder vasculature as a therapeutic target of PDE5 inhibitors. Rodent model studies

Tanaka H, Mitsui R, Oishi M, Passlick S, Jabs R, Steinhäuser C, Tanaka KF, Hashitani H

British journal of pharmacology, 2021

Abstract

BACKGROUND AND PURPOSE: While the bladder vasculature is considered as a target of PDE5 inhibitors to improve bladder storage dysfunctions, its characteristics are largely unknown. Thus, the functional and morphological properties of arteries/arterioles of the bladder focusing on the NO-mediated signal transmission were explored.

EXPERIMENTAL APPROACH: Diameter changes in rat bladder arteries/arterioles were measured using a video-tracking system. Intercellular Ca2+ dynamics in pericytes or smooth muscle cells (SMCs) of suburothelial arterioles were visualised using transgenic mice expressing GCaMP6 under control of the NG2- or parvalbumin-promoter. The perivascular innervation was investigated using fluorescence immunohistochemistry.

KEY RESULTS: In rat suburothelial arterioles and vesical arteries, tadalafil (100 nM) attenuated nerve-evoked sympathetic vasoconstrictions. In both vascular segments, tadalafil-induced inhibition of sympathetic vasoconstriction was prevented by N ω-propyl-l-arginine hydrochloride (l-NPA, 1 μM), an nNOS inhibitor or N ω-nitro-l-arginine (l-NA, 100 μM). Both vascular segments were densely innervated with nNOS-positive nitrergic nerves in close apposition to tyrosine hydroxylase-immunoreactive sympathetic nerves. In pericyte-covered pre-capillary arterioles of the mouse bladder where sympathetic nerves were absent, nerve stimulation evoked transient reductions in pericyte Ca2+ levels that were shortened by l-NPA and abolished by l-NA. In…

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