The urinary bladder angiotensin system: response to infusions of angiotensin I and angiotensin-converting enzyme inhibitors.
The circulating and urinary bladder tissue concentrations of angiotensin I (ANG I) and angiotensin II [ANG-(1-8)] were examined in anesthetized Sprague-Dawley male rats given an intravenous bolus infusion of either ANG I, the angiotensin-converting enzyme (ACE) inhibitors enalaprilat or ramiprilat, or saline. The mean concentrations of ANG I and ANG-(1-8) were markedly higher in the urinary bladder tissue than in whole blood. There was a significant increase in the concentration of ANG I and ANG-(1-8), both in the urinary bladder tissue and the circulation, after the ANG I infusion. Both ACE inhibitors were associated with an increase in the concentration of whole blood ANG I; however, tissue ANG I levels were significantly increased only following ACE inhibition with ramiprilat but not with enalaprilat. Both plasma and urinary bladder tissue ANG-(1-8) levels decreased significantly following ACE inhibition, but only with ramiprilat. The elevated urinary bladder tissue levels of ANG I and ANG-(1-8) at baseline, compared with circulating levels, and the maintenance of ANG-(1-8) in bladder tissue in the face of inhibition of the circulatory renin-angiotensin system with enalaprilat support the presence of an autocrine/paracrine renin-angiotensin system in the urinary bladder. Under the current experimental conditions, ramiprilat appears to have enhanced bladder activity compared with enalaprilat.
Weaver-Osterholtz
D
D
Department of Surgery, University of Missouri, Columbia, MO 65212, USA.
Reams
G
G
Wu
Z
Z
Knaus
J
J
Campbell
F
F
Bauer
J H
JH
D000758:Anesthesia; D000803:Angiotensin I / Q000378:metabolism* / Q000494:pharmacology*; D000804:Angiotensin II / Q000378:metabolism*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D015773:Enalaprilat / Q000494:pharmacology; D008297:Male; D017257:Ramipril / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D001743:Urinary Bladder / Q000378:metabolism*
D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; C052549:ramiprilat; D000803:Angiotensin I; D015773:Enalaprilat; D017257:Ramipril