Effects of clenbuterol on rabbit vesicourethral muscle contractility.
Clenbuterol (10(-10)-10(-7) M), a selective beta 2-adrenoceptor agonist, reduced spontaneous contractile force of isolated rabbit bladder dome, bladder base and proximal urethra. Clenbuterol inhibited both acetylcholine (Ach)-and electrical field stimulation (EFS)-induced contractions of rabbit bladder dome, but was more potent in inhibiting EFS-than Ach-induced contractions. Acetylcholine-but not EFS-induced contractions in the bladder dome were completely inhibited by pretreatment with 10(-6) M atropine. The atropine resistant component of the EFS-induced contractions was completely inhibited by tetrodotoxin, 10(-6) M. Clenbuterol and a non-selective beta-adrenoceptor agonist, isoproterenol, potentiated the EFS-induced contractions of isolated striated muscle preparations from the external urethral sphincter and from the extensor digitorum longus in the rabbit. Clenbuterol was more potent than isoproterenol in increasing EFS-induced contractile force in the external urethral sphincter, whereas isoproterenol was more potent than clenbuterol in increasing EFS-induced contractile force in the extensor digitorum longus. These data suggest that clenbuterol may have a role in the treatment of urinary incontinence by inhibiting the detrusor contraction and fascilitating the external urethral sphincter selectively.
Morita
T
T
Department of Urology, Tokyo Medical and Dental University, School of Medicine, Japan.
Kihara
K
K
Nagamatsu
H
H
Oshima
H
H
Kishimoto
T
T
D000109:Acetylcholine / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002976:Clenbuterol / Q000494:pharmacology*; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D011817:Rabbits; D014521:Urethra / Q000187:drug effects; D001743:Urinary Bladder / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D001285:Atropine; D007545:Isoproterenol; D000109:Acetylcholine; D002976:Clenbuterol