Marumo F, Edelman I S
J Clin Invest. 1971 Aug;50(8):1613-20. doi: 10.1172/JCI106649.
Adenyl cyclase activity was assayed in crude homogenates of the renal cortex, medulla, and papilla of the golden hamster. The specific activity (moles C-AMP/unit of time per mg protein of tissue) of the enzyme under basal conditions, was greatest in papilla, somewhat lower in medulla, and least in cortex. On an absolute scale, the sensitivity to vasopressin was greater in the medullary and papillary than in the cortical homogenates. In addition, at concentrations of 0.1-1.0 mm, CaCl(2) inhibited the enzyme in the order papilla > medulla > cortex. These results imply the existence of distinct differences in the composition of the adenyl cyclase-receptor complex in various parts of the kidney. We proposed that Ca(++) inhibits the core enzyme directly since at the minimally inhibitory concentration (0.1 mm), CaCl(2) reduced to an equivalent extent (a) basal activity, (b) the response to graded doses of vasopressin (0.5 to 50.0 mU/ml) and (c) the response to maximal stimulatory concentrations of NaF (10 mm). Prostaglandin E(1) (PGE(1) = 10(-7)m) had no effect on either basal adenyl-cyclase activity or the response to 10 mm NaF in medullary and papillary homogenates. 7-Oxa-13-prostynoic acid (10(-4)m) similarly had no effect under basal conditions or on stimulation with NaF in medullary homogenates. Both fatty acids, however, inhibited the enzymic response to vasopressin, particularly at low concentrations of the peptide. The straight-chain fatty acid, 11-eicosanoic acid (10(-7)m), was inactive on basal activity or on the response to vasopressin. The possibility that PGE(1) modifies the coupling mechanism between the core enzyme and the hormone-specific receptor is discussed.
对金黄仓鼠肾皮质、髓质和乳头的粗匀浆进行了腺苷酸环化酶活性测定。在基础条件下，该酶的比活性（每毫克组织蛋白每单位时间的C-AMP摩尔数）在乳头中最高，在髓质中稍低，在皮质中最低。从绝对水平来看，髓质和乳头匀浆对血管加压素的敏感性高于皮质匀浆。此外，在0.1 - 1.0毫米的浓度下，氯化钙对该酶的抑制作用顺序为乳头＞髓质＞皮质。这些结果表明肾脏不同部位的腺苷酸环化酶 - 受体复合物组成存在明显差异。我们提出钙离子直接抑制核心酶，因为在最小抑制浓度（0.1毫米）时，氯化钙同等程度地降低了：（a）基础活性，（b）对不同剂量血管加压素（0.5至50.0毫单位/毫升）的反应，以及（c）对最大刺激浓度氟化钠（10毫米）的反应。前列腺素E1（PGE1 = 10^(-7)摩尔）对髓质和乳头匀浆的基础腺苷酸环化酶活性或对10毫米氟化钠的反应均无影响。7-氧杂-13-前列腺炔酸（10^(-4)摩尔）在基础条件下或对髓质匀浆用氟化钠刺激时同样无影响。然而，这两种脂肪酸均抑制对血管加压素的酶促反应，尤其是在该肽的低浓度时。直链脂肪酸11-二十烷酸（10^(-7)摩尔）对基础活性或对血管加压素的反应无活性。文中讨论了PGE1改变核心酶与激素特异性受体之间偶联机制的可能性。
