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首页> 外文期刊>American Journal of Physiology >Unique regulation of anion/HCO3- exchangers by constitutive nitric oxide in rabbit small intestine.
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Unique regulation of anion/HCO3- exchangers by constitutive nitric oxide in rabbit small intestine.

机译：组成型一氧化氮在兔小肠中对阴离子/ HCO3-交换子的独特调节。

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摘要

In the rabbit small intestine, there are three functionally different brush-border membrane (BBM) anion/HCO3- exchangers: 1) Cl/HCO3- exchange on the BBM of villus cells responsible for coupled NaCl absorption; 2) Cl/HCO3- exchange on the BBM of crypt cells possibly involved in HCO3- secretion; and 3) short-chain fatty acid (SCFA)/HCO3- exchange on the BBM of villus cells, which facilitates SCFA absorption. Although constitutive nitric oxide (cNO) has been postulated to alter many gastrointestinal tract functions, how cNO may specifically alter these three transporters is unknown. Inhibition of cNO synthase with NG-nitro-L-arginine methyl ester (L-NAME) 1) did not affect villus cell BBM Cl/HCO3 change, 2) stimulated crypt cell BBM Cl/HCO3- exchange, and 3) inhibited villus cell BBM SCFA/HCO3- exchange. D-NAME, an inactive analog of L-NAME, and L-N6-(1-iminoethyl)lysine, a more selective inhibitor of inducible NO, did not affect these transport processes. Kinetic studies demonstrated that 1) the mechanism of inhibition of crypt cell BBM Cl/HCO3- exchange is secondary to a decrease in the maximal rate of uptake of Cl, without an alteration in the affinity of the transporter for Cl, and 2) the mechanism of stimulation of villus cell BBM SCFA/HCO3- exchange is secondary to an increase in the affinity of the transporter for SCFA without an alteration in the maximal rate of uptake of SCFA. These results indicate that cNO uniquely regulates the three BBM anion/HCO3- transporters in the rabbit small intestine.
机译：在兔小肠中，存在三种功能不同的刷状边界膜（BBM）阴离子/ HCO3-交换剂：1）负责耦合NaCl吸收的绒毛细胞的BBM上的Cl / HCO3-交换; 2）可能参与HCO3-分泌的隐窝细胞在BBM上进行Cl / HCO3-交换; 3）在绒毛细胞的BBM上的短链脂肪酸（SCFA）/ HCO3-交换，促进了SCFA的吸收。尽管已经假定本构性一氧化氮（cNO）会改变许多胃肠道功能，但尚不清楚cNO如何特异性改变这三种转运蛋白。用NG-硝基-L-精氨酸甲酯（L-NAME）抑制cNO合酶1）不影响绒毛细胞BBM Cl / HCO3的变化，2）刺激隐窝细胞BBM Cl / HCO3-的交换，3）抑制绒毛细胞BBM SCFA / HCO3-交换。 D-NAME（L-NAME的无活性类似物）和L-N6-（1-亚氨基乙基）赖氨酸（诱导型NO的选择性更高的抑制剂）不影响这些转运过程。动力学研究表明，1）隐窝细胞BBM Cl / HCO3-交换的抑制机制是继Cl的最大吸收速率降低后，而不改变转运蛋白对Cl的亲和力，以及2）机理绒毛细胞BBM刺激的机理是SCFA / HCO3-交换是转运蛋白对SCFA亲和力增加的继发现象，而不会改变SCFA的最大吸收速率。这些结果表明，cNO独特地调节了兔子小肠中的三种BBM阴离子/ HCO3-转运蛋白。

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