Verma S C, McNeill J H
J Pharmacol Exp Ther. 1976 Sep;198(3):539-47.
There is some evidence in the literature that catecholamines relax uterine and other types of smooth muscle by increasing tissue levels of cyclic adenosine monophosphate (cyclic AMP). In the present study, isoproterenol completely relaxed uterine strips obtained from estrogen-primed rats and also increased tissue levels of cyclic AMP and phosphorylase a. In uterine strips depolarized and put into contracture for 15 minutes by 127 mM K+, isoproterenol did not increase phosphorylase a or cyclic AMP but was still capable of producing relaxation. When uterine strips were exposed to the methoxy derivative of verapamil, D-600, a compound known to prevent the influx of calcium, the uterus relaxed completely without an increase in cyclic AMP. The addition of isoproterenol at this stage resulted in an increase in cyclic AMP similar to that noted in nondepolarized uterine strips. The addition of 127 mM K+ also resulted in time-dependent biochemical changes as well as contracture. Cyclic AMP was increased 3-fold after 2 minutes of K+ depolarization and phosphorylase a was increased as well. The increase in cyclic AMP was prevented by propranolol but propranolol did not affect the contracture response to K+. D-600 prevented contracture but did not affect the K+-induced increase in cyclic AMP. The data suggest that an increase in whole tissue levels of cyclic AMP are not necessary in order for isoproterenol to relax depolarized rat uterine strips. The data also suggest that intracellular calcium levels can affect the level of cyclic AMP in the rat uterus.
文献中有一些证据表明，儿茶酚胺通过增加环磷酸腺苷（cAMP）的组织水平来松弛子宫和平滑肌的其他类型。在本研究中，异丙肾上腺素完全松弛了从用雌激素预处理的大鼠获得的子宫条，并且还增加了cAMP和磷酸化酶a的组织水平。在子宫条被127 mM K⁺去极化并挛缩15分钟后，异丙肾上腺素没有增加磷酸化酶a或cAMP，但仍能够产生松弛作用。当子宫条暴露于维拉帕米的甲氧基衍生物D - 600时，D - 600是一种已知可阻止钙内流的化合物，子宫完全松弛，cAMP没有增加。在此阶段加入异丙肾上腺素会导致cAMP增加，类似于在未去极化子宫条中观察到的情况。加入127 mM K⁺也会导致随时间变化的生化变化以及挛缩。K⁺去极化2分钟后，cAMP增加了3倍，磷酸化酶a也增加了。普萘洛尔可阻止cAMP的增加，但普萘洛尔不影响对K⁺的挛缩反应。D - 600可阻止挛缩，但不影响K⁺诱导的cAMP增加。数据表明，异丙肾上腺素松弛去极化的大鼠子宫条并不一定需要全组织cAMP水平的增加。数据还表明，细胞内钙水平可影响大鼠子宫中cAMP的水平。
