Bramuglia G F, Rubio M C
Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, ININFA (CONICET), 1113 Buenos Aires, Argentina.
Pharmacol Res. 2001 Feb;43(2):151-4. doi: 10.1006/phrs.2000.0752.
Previous works have shown that the administration of the racemic beta -adrenoceptor agent clenbuterol produces a desensitization of the relaxant response in rat uterus. The aim of this work was to study the effects of the optical isomers of clenbuterol on the relaxant response in rat uterus. The administration of (L)-clenbuterol (0.25 mg per kg per day) over 1 or 10 consecutive days, produced a reduction of the relaxant response to isoproterenol in uterine rings precontracted with 50 m m KCl from oestrogenic rats. The administration of (D)-clenbuterol (0.25 mg per kg per day) over 1 or 10 days did not affect the relaxant response of isoproterenol. (L)-clenbuterol also produced a concentration-dependent relaxant effect that was not observed with (D)-clenbuterol. These results show that the beta-adrenergic relaxant response and the desensitization of the relaxant effect to isoproterenol is due to the (L)-isomer and that the (D)-isomer is not involved in these effects.
先前的研究表明，消旋β-肾上腺素能受体激动剂克伦特罗的给药会使大鼠子宫的舒张反应脱敏。本研究的目的是研究克伦特罗的光学异构体对大鼠子宫舒张反应的影响。连续1天或10天给予（L）-克伦特罗（每天0.25毫克/千克），会使来自雌激素处理大鼠的、用50毫摩尔氯化钾预收缩的子宫环对异丙肾上腺素的舒张反应降低。连续1天或10天给予（D）-克伦特罗（每天0.25毫克/千克），对异丙肾上腺素的舒张反应没有影响。（L）-克伦特罗还产生了浓度依赖性的舒张作用，而（D）-克伦特罗未观察到这种作用。这些结果表明，β-肾上腺素能舒张反应以及对异丙肾上腺素舒张作用的脱敏是由（L）-异构体引起的，而（D）-异构体不参与这些作用。
