Effect of angiotensin II on corpus cavernosum smooth muscle in relation to nitric oxide environment: in vitro studies in canines.
In extracavernosal vascular tissue, smooth muscle tone is modulated by a balance between angiotensin II (Ang II) and nitric oxide (NO). We hypothesized that these substances also play an important role in regulating cavernosal smooth muscle contractility. We therefore studied the in vitro effects of an Ang II receptor antagonist and a nitric oxide synthase (NOS) inhibitor on the contractile effects of Ang II, phenylephrine, and electrical field stimulation in canine corpus cavernosum. Ang II caused a dose-dependent contraction of cavernosal smooth muscle which was inhibited by the Ang II receptor antagonist and augmented by NOS inhibition. Contractions induced by phenylephrine or electrical stimulation were diminished by the Ang II receptor antagonist, and augmented by NOS inhibition. We conclude that Ang II plays an important role in modulating cavernosal smooth muscle tone, and that the contractile effect of Ang II on cavernosal tissue is modulated by the local NO environment.
Comiter
C V
CV
Division of Urology, West Roxbury V.A. Medical Center, Massachusetts 02132, USA.
Sullivan
M P
MP
Yalla
S V
SV
Kifor
I
I
D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010413:Penis; D010656:Phenylephrine / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D004791:Enzyme Inhibitors; D000804:Angiotensin II; D010656:Phenylephrine; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019808:Losartan; D019331:NG-Nitroarginine Methyl Ester