Johansson S R, Anderson R G
Acta Pharmacol Toxicol (Copenh). 1978 May;42(5):347-53. doi: 10.1111/j.1600-0773.1978.tb02215.x.
Isoprenaline markedly relaxed rat uterine muscle and increased its content of cyclic AMP. The cyclic AMP concentration reached its highest value, about ten times the control after 3 min., after which it declined rather quickly at first but later more slowly. After 60 min. the cyclic AMP content reached twice the prestimulation value. The muscle remained relaxed all the time. If the incubation medium from the uterus treated with isoprenaline for 60 min. was added to a fresh muscle, a normal response was elicited. Addition of a new dose of isoprenaline to a muscle previously incubated with isoprenaline for 60 min. only gave a minimal rise in cyclic AMP after 3 min. The presence of catechol or corticosterone, which both decreased the inactivation of isoprenaline, showed no effect on the decrease of the isoprenaline-stimulated cyclic AMP level. Nor could the decrease in the cyclic AMP response be prevented in the presence of GTP,F-, adenosine or in Ca2+-deficient medium. The addition of theophylline and puromycin both lead to a slower decline of cyclic AMP content, but after 60 min. the value returned to near that seen ater only isoprenaline. Our studies on isoprenaline-induced desensitization of rat uterus have led us to the conclusion that the change in the capacity of the preparations to accumulate cyclic AMP may be a result of either changes in the beta-adrenoceptors or in the cyclase-system.
异丙肾上腺素能显著舒张大鼠子宫平滑肌，并增加其环磷酸腺苷（cAMP）含量。cAMP浓度在3分钟时达到最高值，约为对照组的10倍，此后起初迅速下降，但随后下降速度减慢。60分钟后，cAMP含量达到刺激前值的两倍。在此期间，子宫平滑肌一直保持舒张状态。如果将经异丙肾上腺素处理60分钟的子宫孵育液加入新鲜子宫平滑肌中，可引发正常反应。向预先用异丙肾上腺素孵育60分钟的子宫平滑肌中再加入一剂异丙肾上腺素，3分钟后cAMP仅出现微量升高。儿茶酚或皮质酮均能降低异丙肾上腺素的失活，但对异丙肾上腺素刺激的cAMP水平降低没有影响。在存在鸟苷三磷酸（GTP）、氟离子（F-）、腺苷或在缺钙培养基中时，也无法阻止cAMP反应的降低。加入茶碱和嘌呤霉素均导致cAMP含量下降速度减慢，但60分钟后，其值又恢复到仅用异丙肾上腺素处理后的水平附近。我们对异丙肾上腺素诱导大鼠子宫脱敏的研究得出结论，制剂积累cAMP能力的变化可能是β-肾上腺素能受体或环化酶系统变化的结果。
