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Hormonal Regulation of Water and Electrolyte Transport in the Colon

结肠中水和电解质运输的激素调节

基本信息

批准号：
06670536
负责人：
HANAI Hiroyuki
金额：
$ 1.41万
依托单位：
Hamamatsu University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Arginine vasopressin (AVP) plays an important role in fluid and electrolyte homeostasis, but its effect on intestinal transport is not fully elucidated. We examined the effect of AVP on colonic mucosal transport using Ussing chambers and cytosolic calcium concentration ([Ca^<2+>]_i) using fura-2 in guinea pig distal colonic epithelium. Serosally added 0.1 nM-1 mM-AVP caused concentration dependent changes in short circuit current (Isc) and tissue conductance (Gt). They include a bumetanide (0.1 mM,serosal)-sensitive increase in Isc which shows electrogenic Cl secretion, and a bumetanide (0.1 mM,serosal)-sensitive decrease in Isc which means electrogenic K^+ secretion. Both changes in Isc were associated with increases in Gt. On the other hand, AVP caused an amiloride (0.1 mM,mucosal)-sensitive decrease in Isc and Gt which coincided inhibition of electrogenic Na^+ absorption. AVP also caused biphasic increases in [Ca^<2+>]_i of crypt cells in a concentration dependent manner. [Ca^<2+>]_i in surface epithelial cells also responded to AVP.All these responses to AVP were abolished by a vasopressin V_1-antagonist. These studies indicate that AVP mobilizes [Ca^<2+>]_i via V_1-receptor, stimulates both bumetanide-sensitive K^+ and Cl^- secretion, and inhibits an amiloride-sensitive Na^+ absorption in guinea pig distal colon.

精氨酸加压素（AVP）在体液和电解质平衡中起重要作用，但其对肠道转运的作用尚未完全阐明。我们用Ussing小室检测了AVP对豚鼠远端结肠粘膜转运的影响，用Fura-2检测了AVP对豚鼠远端结肠上皮细胞内钙离子浓度（[Ca^2+] i）的影响。血清中加入0.1 nM-1 mM-AVP引起短路电流（Isc）和组织电导（Gt）的浓度依赖性变化。它们包括布美他尼（0.1 mM，丝氨酸蛋白酶）敏感的Isc增加，这表明产电性Cl分泌，以及布美他尼（0.1 mM，丝氨酸蛋白酶）敏感的Isc降低，这意味着产电性K^+分泌。Isc的这两种变化都与Gt的增加有关。另一方面，AVP引起了阿米洛利（0.1 mM，粘膜）敏感的Isc和Gt的降低，这与生电Na^+吸收的抑制相一致。AVP还可引起隐窝细胞内[Ca^<2+>] i呈浓度依赖性的双相升高。[Ca AVP对上皮细胞膜表面的^<2+>]_i也有明显的反应，AVP对上皮细胞膜表面的^<2+>]_i的反应可被加压素V_1拮抗剂所阻断。这些研究表明AVP通过V_1受体动员豚鼠远端结肠[Ca^<2+>]_i，刺激布美他尼敏感的K^+和Cl^-分泌，并抑制阿米洛利敏感的Na^+吸收。