Beta-adrenoceptor desensitization by/clenbuterol in rat uterus.
1. The relaxant response and cAMP production mediated by stimulation of isoproterenol is reduced in uterine rings from clenbuterol treated rats (0.25 mg kg-1 s.c. 24 hr before experiments) precontracted with 50 mM KCl. 2. Forskolin, in contrast, showed similar relaxant responses in untreated or clenbuterol treated rats. 3. Isoproterenol produces a biphasic response that is composed of a rapid relaxation followed by a slower regaining of tension, which is considered as desensitization. 4. The kinetic study demonstrates marked changes in the desensitization process of beta-adrenoceptors after clenbuterol administration.
Bramuglia
G F
GF
Catedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas--CONICET, Argentina.
Kazanietz
M G
MG
Pezman
E
E
Enero
M A
MA
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002976:Clenbuterol / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D009126:Muscle Relaxation / Q000187:drug effects; D010646:Phentolamine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014599:Uterus / Q000187:drug effects* / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D005576:Colforsin; D004958:Estradiol; D011189:Potassium Chloride; D000242:Cyclic AMP; D007545:Isoproterenol; D002976:Clenbuterol; D010646:Phentolamine