title: Neurohumoral regulation of spontaneous constrictions in suburothelial venules of the rat urinary bladder.
abstract: 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 bath-applied bioactive substances were investigated. The innervation of the suburothelial microvasculature was examined by immunohistochemistry. EFS (10Hz for 30s) induced an increase in the frequency of SVCs that was prevented by phentolamine (1μM). In phentolamine-pretreated venules, EFS suppressed SVCs with a venular dilatation in a manner attenuated by propranolol (1μM) or l-nitro arginine (LNA, 10μM). BRL37344 (1μM), a β3 adrenoceptor agonist, dilated venules and reduced the frequency of SVCs in an LNA-sensitive manner. ACh (1-10μM) increased the frequency of SVCs. ATP (1μM) transiently constricted venules and then caused LNA-sensitive cessation of SVCs associated with a dilatation. Substance P (100nM) caused a venular constriction, whilst calcitonin gene related peptide (CGRP, 100nM) 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 α-adrenergic stimulation, but suppressed upon β-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.
authors.affiliation: Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mochizuki
authors.affiliation: Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Retsu
authors.initials: R
authors.lastname: Mitsui
authors.affiliation: Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan. Electronic address: hasitani@med.nagoya-cu.ac.jp.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Hashitani
mesh_terms: D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D004558:Electric Stimulation; D007150:Immunohistochemistry; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000494:pharmacology; D001743:Urinary Bladder / Q000098:blood supply*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014699:Venules / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D014741:Video Recording
chemical_list: D013373:Substance P; D011433:Propranolol; D015740:Calcitonin Gene-Related Peptide; D010646:Phentolamine
keywords: Adrenergic nerve; Bladder; Microcirculation; Suburothelium; Vasomotion