DUAL ION-CHANNEL REGULATION BY CYCLIC-GMP AND CYCLIC GMP-DEPENDENT PROTEIN-KINASE
DUAL ION-CHANNEL REGULATION BY CYCLIC-GMP AND CYCLIC GMP-DEPENDENT PROTEIN-KINASE
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DOI：
10.1038/344336a0
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发表时间：
1990-03-22
期刊：
影响因子：
64.8
通讯作者：
STANTON, BA
中科院分区：
文献类型：
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作者：
LIGHT, DB;CORBIN, JD;STANTON, BA
心钠素通过其第二信使鸟苷3‘，5’-环一磷酸(CGMP)作用，抑制肾内髓内集合管对Na+的吸收，增加尿钠排泄。膜片钳研究表明，cGMP通过抑制顶膜上对阿米洛利敏感的阳离子通道来减少Na+的吸收。我们现在已经用膜片钳技术研究了cGMP抑制的分子机制。通过磷酸化非依赖性机制，环状GMP可使单个通道开放的概率(开放概率，Po)降低39%(抑制常数Ki=7.6x10−7M)。环状GMP也通过激活cGMP依赖的蛋白激酶(cGMP-激酶)来抑制该通道。外源性cGMP-K通过磷酸化依赖的机制完全抑制该通道。GTP-γ-S激活百日咳毒素敏感的G蛋白，可阻断该通道对cGMP-K的抑制作用。相反，GTP-γ-S可完全逆转PoC对cGMP-K的抑制作用。结合先前研究表明G蛋白激活阳离子通道的结果，这些数据表明cGMP-激酶和G蛋白顺序地调节阳离子通道。我们的结果表明，心房利钠肽通过cGMP作用于延髓内侧集合管，通过双重机制抑制Na+的吸收，cGMP-K通过G蛋白途径抑制该通道。
ATRIAL natriuretic peptide, acting through its second messenger guanosine 3',5'-cyclic monophosphate (cGMP), suppresses Na+absorption across the renal inner-medullary collecting duct and increases urinary Na+excretion. Patch clamp studies show that cGMP reduces Na+absorption by inhibiting an amiloride-sensitive cation channel in the apical membrane. We have now examined, using the patch clamp technique, the molecular mechanisms of cGMP inhibition. Cyclic GMP directly and specifically reduced the probability of a single channel being open (open probability,Po) by 39% (inhibition constant,Ki= 7.6 x 10−7M) by a phos-phorylation-independent mechanism. Cyclic GMP also inhibited the channel by activating cGMP-dependent protein kinase (cGMP-kinase). Exogenous cGMP-kinase completely inhibited the channel by a phosphorylation-dependent mechanism. Activation of a pertussis toxin-sensitive G protein by GTP-γ-S blocked cGMP-kinase inhibition of the channel. By contrast, cGMP-kinase inhibition ofPowas completely reversed by GTP-γ-S. Taken together with the results of a previous study showing that a G protein activates the cation channel, these data indicate that cGMP-kinase and a G protein sequentially regulate the cation channel. Our results show that atrial natriuretic peptide, acting through cGMP, inhibits Na+absorption across the inner-medullary collecting duct by a dual mechanism, and that cGMP-kinase inhibits the channel by a pathway involving a G protein.