Neurohumoral regulation of spontaneous constrictions in suburothelial venules of the rat urinary bladder

作者：Shimizu Yuki; Mochizuki Satoshi; Mitsui Retsu; Hashitani Hikaru^*

来源：Vascular Pharmacology, 2014, 60(2): 84-94.

DOI：10.1016/j.vph.2014.01.002

• Microcirculation
• Bladder
• Suburothelium
• Vasomotion
• Adrenergic nerve

Venules of the bladder suburothelium develop spontaneous phasic constrictions that may play a critical role in maintaining venular drainage of tissue metabolites. We aimed to investigate neurohumoral regulation of the spontaneous venular constrictions (SVCs). Changes in venular diameter of the rat bladder suburothelium were monitored using a video tracking system, whilst the effects of electrical field stimulation (EFS) and bathapplied bioactive substances were investigated. The innervation of the suburothelial microvasculature was examined by immunohistochemistry. EFS (10 Hz for 30 s) induced an increase in the frequency of SVCs that was prevented by phentolamine (1 mu M). In phentolamine-pretreated venules, EFS suppressed SVCs with a venular dilatation in a manner attenuated by propranolol (1 mu M) or L-nitro arginine (LNA, 10 mu M). BRL37344 (1 mu M), a beta(3) adrenoceptor agonist, dilated venules and reduced the frequency of SVCs in an LNA-sensitive manner. ACh (1-10 mu M) increased the frequency of SVCs. ATP (1 mu M) transiently constricted venules and then caused LNA-sensitive cessation of SVCs associated with a dilatation. Substance P (100 nM) caused a venular constriction, whilst calcitonin gene related peptide (CGRP, 100 nM) caused a dilatation of venules and suppression of SVCs that were not inhibited by LNA. Immunohistochemical staining demonstrated sympathetic as well as substance P- and CGRP-containing nerves running along the venules. Spontaneous constrictions of suburothelial venules are accelerated by sympathetic alpha-adrenergic stimulation, but suppressed upon beta-adrenergic stimulation. In addition, suburothelial venular constrictions appear to be modulated by several bioactive substances that could be released from urothelium or suburothelial sensory nerves.

• 出版日期2014-2