Vasopressin and hyperosmolality regulate NKCC1 expression in rat OMCD
Vasopressin and hyperosmolality regulate NKCC1 expression in rat OMCD
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DOI：
10.1038/hr.2009.52
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发表时间：
2009-08
影响因子：
5.4
通讯作者：
S. Wakamatsu;H. Nonoguchi;M. Ikebe;K. Machida;Y. Izumi;Hasiyet Memetimin;Y. Nakayama;T. Nakanishi;Y. Kohda;K. Tomita
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文献类型：
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作者：
S. Wakamatsu;H. Nonoguchi;M. Ikebe;K. Machida;Y. Izumi;Hasiyet Memetimin;Y. Nakayama;T. Nakanishi;Y. Kohda;K. Tomita
已知分泌型Na-K-2Cl协同转运蛋白（NKCC 1）在酸和钠排泄中发挥作用，并且在脱水中更丰富。为探讨脱水刺激NKCC 1表达的机制，采用RT-竞争性PCR和Western blot方法研究了加压素、催产素和高渗对大鼠外髓集合管（OMCD）NKCC 1 mRNA和蛋白表达的影响。将显微切割的OMCD在等渗或高渗溶液中，或与AVP或催产素在37 ℃下孵育60分钟。在体外，NaCl、甘露醇或棉子糖诱导的高渗可使OMCD中NKCC 1 mRNA表达增加130-240%。NaCl对NKCC 1 mRNA表达的刺激在690 mosmol kg− 1 H2 O时最高，在较高渗透压下逐渐降低。用AVP（10− 7 M）孵育OMCD 60分钟，NKCC 1 mRNA表达增加100%。使用渗透性微型泵向大鼠给予AVP 4天也使OMCD中NKCC 1 mRNA和蛋白表达增加了130%。相反，催产素（10− 7 M）在体外并不刺激OMCD中NKCC 1 mRNA的表达。慢性注射催产素使NKCC 1 mRNA表达增加36%。这些数据表明，高渗和加压素刺激大鼠OMCD中NKCC 1 mRNA和蛋白的表达。结论：NKCC 1的表达受加压素的直接和间接调节。
Secretory-type Na-K-2Cl cotransporter (NKCC1) is known to play roles in both acid and sodium excretion, and is more abundant in dehydration. To determine the mechanisms by which dehydration stimulates NKCC1 expression, the effects of vasopressin, oxytocin and hyperosmolality on NKCC1 mRNA and protein expressions in the outer medullary collecting duct (OMCD) of rats were investigated using RT-competitive PCR and western blot analysis. Microdissected OMCD was incubated in isotonic or hypertonic solution, or with AVP or oxytocin for 60 min at 37 C. Hyperosmolality induced by NaCl, mannitol or raffinose increased NKCC1 mRNA expression in OMCD by 130–240% in vitro. The stimulation of NKCC1 mRNA expression by NaCl was highest at 690 mosmol kg− 1 H 2 O and gradually decreased at higher osmolalities. The incubation of OMCD with AVP (10− 7 M) for 60 min increased NKCC1 mRNA expression by 100%. The administration of AVP to rats for 4 days using an osmotic mini-pump also increased NKCC1 mRNA and protein expressions in OMCD by 130%. In contrast, oxytocin (10− 7 M) did not stimulate the NKCC1 mRNA expression in OMCD in vitro. Chronic injection of oxytocin increased the NKCC1 mRNA expression by 36%. These data showed that hyperosmolality and vasopressin stimulate NKCC1 mRNA and protein expressions in rat OMCD. It is concluded that NKCC1 expression is regulated directly and indirectly by vasopressin.