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首页> 外文期刊>Journal of Cellular Physiology >Roles of ATP and cytoskeleton in the regulation of Na+/H+ exchanger along the nephron luminal membrane.
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Roles of ATP and cytoskeleton in the regulation of Na+/H+ exchanger along the nephron luminal membrane.

机译：角色的ATP和细胞骨架的规定Na + / H +沿肾元腔的换热器膜。

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Although in LLC-PK cells ATP depletion has been shown to result in alterations of cytoskeleton actin and an inhibition of Na+/H+ exchanger activity, there is little information concerning the regulation of this exchanger in the distal luminal membrane by ATP and actin filaments. The present study examined the direct effect of ATP and cytochalasin B on the Na+/H+ exchanger activity in the proximal and distal tubule luminal membranes. The presence of 100 microM ATP in the luminal membrane vesicles from rabbit proximal tubules did not influence the Ethyl Isopropyl Amiloride sensitive Na+ uptake by these membranes. In contrast, the same treatment of luminal membranes from distal tubules significantly enhanced the exchanger activity from 0.22 +/- 0.04 to 0.39 +/- 0.08 pM/microg/10 sec (P < 0.02). When ATP was replaced by its nonhydrolysable form, ATPgammas, the effect on the distal luminal membrane was strongly diminished suggesting that the action of the nucleotide implicates a phosphorylation step. Confirming this hypothesis, addition of 300-microM-Rp cAMP, a protein kinase A inhibitor, completely abolished the effect of ATP. In view of the fact that a tight relationship has been described between ATP, the cytoskeleton complex and the exchanger activity, we studied the effect of cytochalasin B on this activity. The presence of 20 microM cytochalasin B in the distal luminal membrane vesicles induced, as observed with ATP, a significant increase in the Na+ uptake. However, the actions of ATP and cytochalasin B were not additive. These results suggest that firstly, ATP and short actin filaments of the cytoskeleton regulate the distal luminal isoform through an intramembranous mechanism and secondly, a phosphorylation mechanism is, at least partially, implicated in the action of ATP. In contrast, the proximal tubule exchanger is regulated through different mechanisms. Copyright 2001 Wiley-Liss, Inc.
机译：尽管在LLC-PK细胞ATP耗竭导致细胞骨架的改变肌动蛋白的抑制Na + / H +换热器关于活动,几乎没有信息这种换热器的监管在远端鲁米那膜ATP和肌动蛋白丝。本研究调查了ATP的直接影响和细胞松弛素B在Na + / H +换热器活动在近端和远端小管腔的膜。腔的膜囊泡的兔子近端小管没有影响乙异丙基Na +吸收这些阿米洛利敏感膜。从远端小管腔的膜显著提高了换热器的活动从0.22 + / - 0.04到0.39 + / - 0.08点/ microg / 10秒(P < 0.02)。ATPgammas nonhydrolysable形式,影响远端腔的膜是强烈的减少暗示的作用核苷酸结合磷酸化的一步。证实这一假说,添加300 - microm rp营地,蛋白激酶抑制剂,完全废除了ATP的效果。紧密关系的事实描述之间的ATP,细胞骨架复杂和换热器活动,我们研究了效果细胞松弛素B的活动。在远端腔的20 microM细胞松弛素B膜囊泡诱导,观察ATP,在Na +吸收显著增加。然而,ATP和细胞松弛素B的行为没有添加剂。首先,ATP和短的肌动蛋白丝细胞骨架调节远端腔的同种型通过一个和膜内的机制其次,磷酸化机制,部分,与ATP的作用。相比之下,近端小管换热器通过不同的机制监管。2001 Wiley-Liss, Inc。

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