THIAZIDE-SENSITIVE SODIUM-CHLORIDE COTRANSPORT IN EARLY DISTAL TUBULE
THIAZIDE-SENSITIVE SODIUM-CHLORIDE COTRANSPORT IN EARLY DISTAL TUBULE
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DOI：
10.1152/ajprenal.1987.253.3.f546
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发表时间：
1987-09-01
影响因子：
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通讯作者：
WRIGHT, FS
中科院分区：
文献类型：
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作者：
ELLISON, DH;VELAZQUEZ, H;WRIGHT, FS
至少有两条途径介导钠通过肾小管远端管腔膜的吸收。一个途径是导电通道，另一个似乎是一个耦合的Na-Cl共转运途径。远端小管包括三段：远曲小管、连接小管和初集管。为了提供所提出的钠转运途径的细胞位置信息，我们在麻醉大鼠体内分别灌注全远端束的早期（全远端长度的14-38%）和晚期（全远端长度的61-83%）。当用类似正常到达远端小管的液体（75 mM Na, 68 mM Cl）的溶液灌注时，钠的吸收率在早期和晚期（早期68 .+-）相似。29.6，后期67。27.5 pmol.cntdot.min - 1. - cntdot.mm - 1)。当灌注类似于间质液的溶液（148 mM Na, 110 mM cl）时，钠转运在早期明显高于后期节段(276。28.4 vs. 113。29.7 pmol.cntdot.min - 1. - cntdot.mm - 1)。氯噻嗪（10-3 M）阻断整个远端小管对钠和氯的吸收，使远端小管早期钠和氯的转运降至零，但对远端小管晚期无显著影响。从灌注溶液中去除所有氯化物可减少早期而非晚期远端节段的钠转运。我们得出结论，早期远端小管的钠和氯转运能力大于晚期远端小管，几乎所有早期远端小管的跨细胞钠转运都经过Na-Cl共转运途径，并且其他途径介导了晚期远端小管的大部分钠转运。
At least two pathways mediate sodium absorption across the luminal membrane of the renal distal tubule. One pathway is a conductive channel and the other appears to be a coupled Na-Cl cotransport pathway. The distal tubule comprises three segments: the distal convoluted tubule, the connecting tubule, and the initial collecting duct. To provide information about cellular locations of the proposed sodium transport pathways, we perfused early (14-38% of whole distal length) and late (61-83% of whole distal length) segments of whole distal bundles separately in vivo in anesthetized rats. When perfused with a solution that resembles fluid normally arriving at the distal tubule (75 mM Na, 68 mM Cl), rates of sodium absorption were similar in early and late segments (early 68 .+-. 29.6, late 67 .+-. 27.5 pmol.cntdot.min-1.cntdot.mm-1). When perfused with a solution that resembles interstitial fluid (148 mM Na, 110 mM cl), sodium transport was significantly higher in early than in late segments (276 .+-. 28.4 vs. 113 .+-. 29.7 pmol.cntdot.min-1.cntdot.mm-1). Chlorothiazide (10-3 M), which blocks sodium and chloride absorption in whole distal tubules, reduced sodium and chloride transport to zero in early distal tubules but had no significant effect in late distal tubules. Removing all chloride from perfusion solutions reduced sodium transport in early but not late distal segments. We conclude that the sodium and chloride transport capacity of the early distal tubule is greater than that of the late distal tubule, that virtually all transcellular sodium transport in the early distal tubule traverses a Na-Cl cotransport pathway, and that other pathways mediate the majority of sodium transport by the late distal tubule.