Vegesna R V, Diamond J
Eur J Pharmacol. 1986 Aug 22;128(1-2):25-31. doi: 10.1016/0014-2999(86)90553-4.
The role of cyclic AMP (cAMP) in the control of vascular smooth muscle tension was examined by comparing the effects of prostacyclin (PGI2) on tension and cAMP levels in helical strips of bovine coronary arteries and in rabbit aortic rings, both denuded of endothelium. In bovine coronary arteries, PGI2 elevated cAMP levels and relaxed the muscles. The PGI2-induced cAMP elevation preceded the relaxation and both parameters were altered in a dose-dependent manner by increasing concentrations of PGI2 (0.3, 3 and 30 microM). These results are consistent with a role for cAMP as a mediator of vascular smooth muscle relaxation. Cyclic AMP levels were also elevated by PGI2 in a concentration- and time-dependent manner in rabbit aortic rings. However, in direct contrast to the results in the bovine coronary arteries, PGI2-induced elevation of cAMP in the aortic rings was accompanied by contraction rather than relaxation. Isoproterenol, a drug which is generally believed to relax smooth muscles by virtue of its ability to increase tissue levels of cAMP, relaxed PGI2-contracted aortic rings with no further elevation of cAMP beyond that caused by the PGI2 alone. These results demonstrate that cAMP elevation and relaxation of vascular smooth muscle are not always well correlated. It is possible that some form of functional compartmentalization of cAMP or cAMP-dependent protein kinase exists in these tissues.
通过比较前列环素（PGI2）对牛冠状动脉螺旋条和兔主动脉环（两者均去除内皮）的张力及环磷酸腺苷（cAMP）水平的影响，研究了cAMP在控制血管平滑肌张力中的作用。在牛冠状动脉中，PGI2提高了cAMP水平并使肌肉松弛。PGI2诱导的cAMP升高先于松弛，且随着PGI2浓度（0.3、3和30微摩尔）的增加，这两个参数均呈剂量依赖性改变。这些结果与cAMP作为血管平滑肌松弛介质的作用一致。在兔主动脉环中，PGI2也以浓度和时间依赖性方式提高了cAMP水平。然而，与牛冠状动脉的结果形成直接对比的是，PGI2诱导的主动脉环中cAMP升高伴随着收缩而非松弛。异丙肾上腺素是一种通常被认为通过增加组织cAMP水平来松弛平滑肌的药物，它使PGI2收缩的主动脉环松弛，且cAMP水平没有超过单独使用PGI2时所引起的进一步升高。这些结果表明，cAMP升高与血管平滑肌松弛并不总是密切相关。在这些组织中可能存在某种形式的cAMP或cAMP依赖性蛋白激酶的功能区室化。
