K+ transport in isolated guinea pig colonocytes: evidence for Na(+)-independent ouabain-sensitive K+ pump.
K+ transport in isolated guinea pig colonocytes: evidence for Na(+)-independent ouabain-sensitive K+ pump.
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离体豚鼠结肠细胞中的 K 转运：Na(+) 独立的哇巴因敏感 K 泵的证据。
DOI：
10.1152/ajpgi.1994.266.6.g1083
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
L. Burguillos
中科院分区：
文献类型：
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作者：
J. D. del Castillo;M. C. Súlbaran;L. Burguillos
用86Rb作为示踪剂研究了K+在豚鼠远端结肠上皮细胞中的转运机制。已经确定了一种运输途径，该途径与介导经上皮K+吸收的机制相同。豚鼠结肠细胞至少通过三种不同的机制摄取K+: 1) Na（+）依赖的、瓦阿因敏感的内流与Na(+)-K+泵一致，2)Na（+）依赖的布美他尼敏感的内流与Na(+)-K(+)- 2cl -共转运体一致，3)Na（+）独立的瓦阿巴因敏感内流与根尖结肠K+泵一致。这些运输机制对鱼藤酮和钒酸盐（P型腺苷三磷酸酶（ATPases）阻滞剂）的代谢抑制很敏感。胃K(+)-H(+)- atp酶抑制剂SCH-28080无作用。净K+通量的测量表明，分离的结肠细胞通过两个过程浓缩K+: 1) Na（+）依赖的瓦阿因敏感机制，与Na(+)-K+泵兼容；2)Na（+）独立的瓦阿因敏感机制，与所提出的吸收K+泵一致。鱼藤酮和钒酸盐对这些浓缩机制也有抑制作用，但SCH-28080没有抑制作用。豚鼠远端结肠中存在Na（+）不依赖的瓦巴因敏感K+泵，而近端结肠和小肠中不存在。我们认为，这种不依赖于Na（+）的瓦巴因敏感K+泵介导K+吸收，并与腔内K(+)- atp酶有关。
K+ transport mechanisms in epithelial cells isolated from guinea pig distal colon have been studied using 86Rb as a tracer. A transport pathway has been identified that is proposed to be identical to the mechanism mediating transepithelial K+ absorption. Guinea pig colonocytes take up K+ through at least three separate mechanisms: 1) a Na(+)-dependent, ouabain-sensitive influx that is consistent with the Na(+)-K+ pump, 2) a Na(+)-dependent bumetanide-sensitive influx consistent with the Na(+)-K(+)-2Cl- cotransporter, and 3) a Na(+)-independent ouabain-sensitive influx, consistent with an apical colonic K+ pump. These transport mechanisms are sensitive to metabolic inhibition by rotenone and to vanadate, a blocker of type P adenosinetriphosphatase (ATPases). SCH-28080, an inhibitor of gastric K(+)-H(+)-ATPase, was without effect. Measurements of net K+ fluxes revealed that isolated colonocytes concentrated K+ by two processes: 1) a Na(+)-dependent ouabain-sensitive mechanism, which is compatible with the Na(+)-K+ pump and 2) a Na(+)-independent ouabain-sensitive mechanism consistent with the proposed absorptive K+ pump. These concentrative mechanisms were also inhibited by rotenone and vanadate, but not by SCH-28080. The Na(+)-independent ouabain-sensitive K+ pump was present in the distal colon, but absent in the proximal colon and the small intestine of guinea pig. It is proposed that this Na(+)-independent ouabain-sensitive K+ pump mediates K+ absorption and is related to the luminal K(+)-ATPase.