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Updated: Aug 7, 2026

Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology
Published on: August 18, 2014
[The adrenoceptor and calcitionin-gene related peptide receptor in the striated urethral sphincter in male rabbit]
N Ohnishi1, R Miyatake, K Hashimoto
1Department of Urology, Kinki University School of Medicine.
Background:
The objective of this study is to analyze the adrenoceptor and calcitonin-gene related peptide receptor in the isolated striated urethral sphincter from a male rabbit.
Methods:
The striated urethral sphincter preparations were suspended in 2ml tissue chamber filled with Krebs Ringer solution, and the changes of isometric twitch contraction induced by electrical field stimulation (EFS-contraction) were recorded in the presence of 3-isobutyl-1-methyl-xanthine (IBMX, 10(-5) M).
Results:
The EFS-contraction was almost completely attenuated by tetrodotoxin (TTX, 10(7) M), vecronium (10(-4) M) and suxamethonium (10(-4) M). Norepinephrine (NE, 10(-8) M-10(-4) M) did not affect the EFS-contraction, but increased the tonic contraction in a dose-dependent manner. The tonic contractions induced by NE was significantly blocked by phentolamine (10(-6) M). Clonidine (10(-7) M), yohimbin (10(-7) M) and propranolol (10(-9) M-10(-6) M) did not affect the EFS-contraction. Isoproterenol (10(-9) M-10(-6) M) did not reduce the carbachol (10(-5) M) induced tonic contraction. Calcitonin-gene related paptide (CGRP, 10(-7) M-3 x 10(-6) M) did not affect the EFS-contraction and did not increase the tonic contraction.
Conclusion:
These results suggested that alpha 1-adrenoceptors of the striated urethral sphincter play a role to modulate the resting tension level, but alpha 2-adrenoceptors, beta-adrenoceptors and CGRP receptors play no role in this regard.
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