INHIBITION OF ALPHA-2-ADRENERGIC AGONISTS ON AVP-INDUCED CAMP ACCUMULATION IN ISOLATED COLLECTING TUBULE OF THE RAT-KIDNEY
INHIBITION OF ALPHA-2-ADRENERGIC AGONISTS ON AVP-INDUCED CAMP ACCUMULATION IN ISOLATED COLLECTING TUBULE OF THE RAT-KIDNEY
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DOI：
10.1016/0303-7207(84)90096-0
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发表时间：
1984-01-01
影响因子：
4.1
通讯作者：
MOREL, F
中科院分区：
文献类型：
--
作者：
CHABARDES, D;MONTEGUT, M;MOREL, F
开发了cAMP的微放射免疫测定法以分析α-cAMP的作用。肾上腺素能激动剂对加压素（AVP）诱导的cAMP细胞在单片显微切割的髓质（MCT）和皮质（CCT）大鼠集合管中蓄积的影响。在所选择的实验条件下（在磷酸二酯酶抑制剂存在下孵育4分钟），无论是在浴溶液中还是在非刺激性小管样品中均未检测到cAMP。在MCT中，10-6 M AVP刺激cAMP产生高达128.3 ±。9.0（SEM [平均值的标准误差]）fmol/mm小管/4分钟，N = 11。该反应是剂量依赖性的，Ka值低于10-10 M AVP。在普萘洛尔存在下加入去甲肾上腺素（NE）（10-5 M）抑制了对AVP的大部分反应（从92%到2 × 10 - 5 M）。10-11 M AVP至10-6 M AVP的76%）;添加10-7 M NE仍使MCT对10-10 M AVP的反应降低59%（26.2 ± 0.01）。5.9与64.0 .+-相比。6.4 fmol/mm，N = 3）。在CCT中，10-5 M NE使10-10 M AVP诱导的cAMP产生减少84%（8.8 ± 0.01）。2.0对比54.2 .+-。3.5 fmol/mm，N = 3）。在CCT中NE对AVP效应的这种抑制作用被10-7 M可乐定模拟;在MCT中它被酚妥拉明和育亨宾抑制，但不被哌唑嗪抑制，这表明α 2-肾上腺素受体参与其中。添加α-激动剂加入孵育溶液中对CCT中的胰高血糖素、降钙素和异丙肾上腺素或MCT中的胰高血糖素诱导的cAMP细胞积累没有产生抑制作用，这一观察结果表明α 2-肾上腺素能激动剂选择性地抑制这些肾单位节段的加压素依赖性cAMP产生。
A microradioimmunoassay for cAMP was developed to analyze the effects of .alpha.-adrenergic agonists on vasopressin (AVP)-induced cAMP cell accumulation in single pieces of microdissected medullary (MCT) and cortical (CCT) rat collecting tubules. Under the experimental conditions chosen (4 min of incubation in the presence of a phosphodiesterase inhibitor), no cAMP could be detected either in the bathing solutionor in non-stimulating samples of tubule. In MCT, 10-6 M AVP stimulated cAMP generation up to 128.3 .+-. 9.0 (SEM [standrd error of the mean]) fmol/mm of tubule per 4 min, N = 11. The response was dose-dependent with a Ka value below 10-10 M AVP. The addition of norepinephrine (NE) (10-5 M in the presence of propranolol suppressed the larger part of the response to AVP (from 92% with 2 .times. 10-11 M AVP to 76% with 10-6 M AVP); the addition of 10-7 M NE still reduced by 59% the MCT response to 10-10 M AVP (26.2 .+-. 5.9 vs. 64.0 .+-. 6.4 fmol/mm, N = 3). In CCT, 10-5 M NE reduced by 84% the cAMP generation induced by 10-10 M AVP (8.8 .+-. 2.0 vs. 54.2 .+-. 3.5 fmol/mm, N = 3). This inhibitory action of NE against the AVP effect in CCT was mimicked by 10-7 M clonidine; in MCT it was suppressed by phentolamine and yohimbine, but not by prazosin, suggesting that .alpha.2-adrenoceptors are involved. The addition of the .alpha.-agonists to the incubation solution produced no inhibition of the cAMP cell accumulations induced by glucagon, calcitonin and isoproterenol in CCT, or glucagon in MCT, an observation demonstrating that .alpha.2-adrenergic agonists selectively inhibit vasopressin-dependent cAMP generation by these nephron segments.