Connexin 30 Deficiency Impairs Renal Tubular ATP Release and Pressure Natriuresis
Connexin 30 Deficiency Impairs Renal Tubular ATP Release and Pressure Natriuresis
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DOI：
10.1681/asn.2008101099
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发表时间：
2009-08-01
影响因子：
13.6
通讯作者：
Peti-Peterdi, Janos
中科院分区：
文献类型：
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作者：
Sipos, Arnold;Vargas, Sarah L.;Peti-Peterdi, Janos
在肾小管中，ATP是盐和水重吸收的重要调节剂，但ATP释放的机制尚不清楚。几种连接蛋白（Cx）亚型形成机械敏感性，ATP渗透性半通道。我们将Cx 30定位于远端肾单位细胞的非连接性顶膜，并测试Cx 30是否参与生理上重要的ATP释放。我们解剖，部分分裂开放，并在体外微灌注野生型和Cx 30缺陷小鼠的皮质集合管。我们使用PC 12细胞作为ATP生物传感器，通过用Fluo-4/Fura Red装载它们来测量胞质钙，并将它们定位成与嵌入或主细胞的顶端表面直接接触。ATP生物传感器的反应，触发的增加管流或浴低渗，大约三倍大时，旁边的嵌入细胞比旁边的主细胞。此外，这些反应没有发生在COO-缺陷小鼠或嘌呤受体阻断剂的制剂。通过结扎远端主动脉，然后结扎肠系膜动脉和腹腔动脉，诱导平均动脉压逐步升高后，野生型小鼠的尿量增加了4.2倍，而Cx 30缺陷小鼠增加了2.6倍，野生型小鼠的尿Na+排泄增加了5.2倍，而Cx 30缺陷小鼠增加了2.8倍。此外，U30缺陷小鼠的平均动脉压出现内皮钠通道依赖性、盐敏感性升高。总而言之，我们认为机械敏感性Cx 30半通道通过将ATP释放到管状液中，抑制盐和水的重吸收，在压力尿钠排泄中发挥着不可或缺的作用。
In the renal tubule, ATP is an important regulator of salt and water reabsorption, but the mechanism of ATP release is unknown. Several connexin (Cx) isoforms form mechanosensitive, ATP-permeable hemichannels. We localized Cx30 to the nonjunctional apical membrane of cells in the distal nephron and tested whether Cx30 participates in physiologically important release of ATP. We dissected, partially split open, and microperfused cortical collecting ducts from wild-type and Cx30-deficient mice in vitro. We used PC12 cells as ATP biosensors by loading them with Fluo-4/Fura Red to measure cytosolic calcium and positioning them in direct contact with the apical surface of either intercalated or principal cells. ATP biosensor responses, triggered by increased tubular flow or by bath hypotonicity, were approximately three-fold greater when positioned next to intercalated cells than next to principal cells. In addition, these responses did not occur in preparations from COO-deficient mice or with purinergic receptor blockade. After inducing step increases in mean arterial pressure by ligating the distal aorta followed by the mesenteric and celiac arteries, urine output increased 4.2-fold in wild-type mice compared with 2.6-fold in Cx30-deficient mice, and urinary Na+ excretion increased 5.2-fold in wild-type mice compared with 2.8-fold in Cx30-deficient mice. Furthermore, U30-deficient mice developed endothelial sodium channel-dependent, salt-sensitive elevations in mean arterial pressure. Taken together, we suggest that mechanosensitive Cx30 hemichannels have an integral role in pressure natriuresis by releasing ATP into the tubular fluid, which inhibits salt and water reabsorption.