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Beta-adrenoceptor desensitization by/clenbuterol in rat uterus
G F Bramuglia1, M G Kazanietz, E Pezman
1Catedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas--CONICET, Argentina.
Abstract:
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.