胆碱能药物和咪唑对兔结肠微粒体组分中钙释放和环磷酸腺苷形成的影响。

Effects of cholinergic drugs and imidazole on Ca release and cyclic AMP formation in microsomal fractions from rabbit colon.

作者信息

Nilsson K B, Andersson R G

出版信息

Acta Pharmacol Toxicol (Copenh). 1977 Mar;40(3):389-400.

PMID:190860

Abstract

Following the addition of carbachol or acetylcholine to microsomal fractions isolated from rabbit colon which were preloaded with Ca, the ions were rapidly released. In the 35-45% fraction Ca was completely released within 10 min., but in the 35% fraction only 30% was released. Carbachol reduced the adenylate cyclase activity of the 35-45% fraction. Both these effects were blocked by atropine. Exogenous cyclic AMP completely inhibited the Ca-releasing action of carbachol in the 35% fraction and markedly reduced it in the 35-45% fraction. Imidazole released Ca from the 35-45% fraction and stimulated its phosphodiesterase activity. It is suggested that the microsomal fractions are parts of a Ca-sequestering system in smooth muscle which are able to bind Ca and which on the addition of some contracting drugs release the ions and thereby activate the contractile system. The release of Ca may partly at least be due to a reduction of the adenylate cyclase activity, although other mechanisms must also be considered.

摘要

向预先加载了钙的兔结肠分离的微粒体部分中加入卡巴胆碱或乙酰胆碱后，离子迅速释放。在35% - 45%的部分中，钙在10分钟内完全释放，但在35%的部分中仅释放了30%。卡巴胆碱降低了35% - 45%部分的腺苷酸环化酶活性。这两种作用均被阿托品阻断。外源性环磷酸腺苷完全抑制了卡巴胆碱在35%部分中的钙释放作用，并在35% - 45%部分中显著降低了该作用。咪唑从35% - 45%部分释放钙并刺激其磷酸二酯酶活性。有人提出，微粒体部分是平滑肌中钙螯合系统的一部分，能够结合钙，并且在加入一些收缩药物时释放离子，从而激活收缩系统。钙的释放至少部分可能是由于腺苷酸环化酶活性的降低，尽管也必须考虑其他机制。