Effects of clenbuterol on resting tension and contractile response in vesicourethral smooth muscle of rabbits.

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概要

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• Kishimoto, T., Aoki, K., Okamiya, Y., Takeshita, T. and Naruchi, T. <I>Effects of clen-buterol on resting tension and contractile response in vesicourethral smooth muscle of rabbits.</I> Jpn. J. Smooth Muscle Res, 25: 13-25, 1989.<BR>The effects of clenbuterol, a selective beta<SUB>2</SUB>-agonist, on isolated smooth muscle prepara-tions from the rabbit bladder body, bladder base and proximal urethra havebeen investigat-ed. The inhibitory effects on resting tension and acetylcholine- and field stimulation-induced contractions in the bladder body werecompared with those of flavoxate, atropine, and verapamil.<BR>Clenbuterol (10<SUP>-10</SUP>-10<SUP>-7</SUP> M) had a strong, concentration-dependent relaxant effect on resting tension of the bladder body, and the relaxant effect was antagonized bypropranolol. However, clenbuterol had little effect on the bladder base or proximal urethra. Isoproter-enol, a non-selective beta agonist, gave a similar result, but was less potent than clenbuterol. Flavoxate failed to reduce the resting tension, but rather enhanced the spontaneous rhythmic contraction in a concentration-dependent manner. Atropine had little effect. Verapamil produced a concentration-dependent relaxation in the bladder body.<BR>Acetylcholine-induced contraction in the bladder body was completely inhibited by pretreatment with atropine (10<SUP>-7</SUP> M). Clenbuterol, flavoxate, and verapamil concentration-dependently inhibited acetylcholine-induced contraction. Field stimulation-induced con-traction in the bladder body was not completely inhibited by atropine. However, the residual contraction was completely inhibited by tetrodotoxin. Clenbuterol, flavoxate, and verapamil concentration-dependently inhibited field stimulation-induced contraction. The inhibitory effects of clenbuterol and verapamil were antagonized by an application of propranolol and anincrease in external Ca, respectively.<BR>The data suggest that the selective relaxant effect of clenbuterol on the bladder body is due to beta<SUB>2</SUB>-antagonistic action, resulting in the inhibition of the contractile response to acetylcholine or field stimulation. Also, its response wasdifferent from that of the other drugs used.

• 日本平滑筋学会の論文

著者

• 竹下 徹

  帝人 (株) 医薬開発研究所

• 青木 久美子

  帝人 (株) 医薬開発研究所

• 岸本 直

  帝人 (株) 医薬開発研究所

• 岡宮 芳明

  帝人 (株) 医薬開発研究所

• 成智 達之

  帝人 (株) 生物医学研究所薬理研究部

• 青木 久美子

  帝人 (株) 生物医学研究所薬理研究部

• 岸本 直

  帝人 (株) 生物医学研究所薬理研究部

• 竹下 徹

  帝人 (株) 生物医学研究所薬理研究部

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• Effects of clenbuterol on resting tension and contractile response in vesicourethral smooth muscle of rabbits.

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