O'Dea R F, Zatz M
Proc Natl Acad Sci U S A. 1976 Oct;73(10):3398-402. doi: 10.1073/pnas.73.10.3398.
Guanosine 3':5'-cyclic monophosphate (cGMP) increased 7-fold in rat pineal glands incubated in the presence of l-norepinephrine. This response consisted of two components-one was stereospecific and inhibited by alpha-adrenergic antagonists while the other was not stereospecific and not readily inhibited by antagonists. Although l-isoproterenol was more potent than l-norepinephrine it had less intrinsic activity and its action was not stereospecifc. The increase in cGMP caused by these catecholamines, unlike that of adenosine 3':5'-cyclic monophosphate (cAMP), was dependent upon extracellular calcium. Ouabain and high levels of potassium produced a marked, calcium-dependent increase in pineal cGMP, without affecting cAMP. There was no effect of cholinergic agonists on cGMP. Surgical denervation markedly reduced the cGMP response to stimulation by l-norepinephrine, potassium, or ouabain. This was in contrast to the enhanced response of cAMP in denervated glands. The nonspecific increase in cGMP caused by l-isoproterenol, however, was not affected by denervation. These data demonstrate the existence of a calcium-dependent presynaptic mechanism for the generation of cGMP which may be mediated by an alpha-adrenergic-like receptor. In addition, the mechanisms regulating pineal cGMP appear to be physiologically distinct from those regulating cAMP.
在存在左旋去甲肾上腺素的情况下孵育的大鼠松果体中，鸟苷 3':5'-环一磷酸（cGMP）增加了 7 倍。这种反应由两个部分组成——一个是立体特异性的，可被α-肾上腺素能拮抗剂抑制，而另一个不是立体特异性的，且不易被拮抗剂抑制。尽管左旋异丙肾上腺素比左旋去甲肾上腺素更有效，但它的内在活性较低，且其作用不是立体特异性的。与腺苷 3':5'-环一磷酸（cAMP）不同，这些儿茶酚胺引起的 cGMP 增加依赖于细胞外钙。哇巴因和高钾水平可使松果体 cGMP 显著增加且依赖于钙，而不影响 cAMP。胆碱能激动剂对 cGMP 没有影响。手术去神经支配显著降低了松果体对左旋去甲肾上腺素、钾或哇巴因刺激的 cGMP 反应。这与去神经支配腺体中 cAMP 的增强反应形成对比。然而，左旋异丙肾上腺素引起的 cGMP 非特异性增加不受去神经支配的影响。这些数据表明存在一种依赖于钙的突触前机制来生成 cGMP，这可能由一种类α-肾上腺素能受体介导。此外，调节松果体 cGMP 的机制在生理上似乎与调节 cAMP 的机制不同。
