Ouabain-insensitive salt and water movements in duck red cells. II. Norepinephrine stimulation of sodium plus potassium cotransport
Ouabain-insensitive salt and water movements in duck red cells. II. Norepinephrine stimulation of sodium plus potassium cotransport
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鸭红细胞中哇巴因对盐和水的运动不敏感。
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
Tj McManus
中科院分区：
文献类型：
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作者：
WF Schmidt III;Tj McManus
儿茶酚胺诱导在等渗溶液中孵育的鸭红细胞中的净盐和水运动。这种反应的速率大约是在不存在激素的情况下在400 mosmol高渗溶液中观察到的类似效果的三倍（W.F.施密特和T. J·麦克马纳斯1977 a.J.Gen.Physiol.70：59-79.除此之外，这两种制度有许多相似之处。在这两种情况下，净水和盐的运动有一个显着的依赖于外部阳离子浓度，是敏感的呋塞米和不敏感的哇巴因，并允许外部钾的替代铷。在哇巴因的存在下，但没有外部钾（或铷），钠对一个大的电化学梯度的呋塞米敏感的净挤出可以证明。当去甲肾上腺素处理的细胞与哇巴因和足够的外部钠一起孵育时，钠和铷的呋塞米敏感性单向流入在相似的铷浓度下是半最大饱和的;在饱和的外部铷的情况下，相同的通量在可比的外部钠水平下是半最大的。在钠的情况下，持续存在的儿茶酚胺刺激，呋塞米敏感的铷流入。在不存在铷的情况下，可以看到类似但较小的钠内流组分。我们解释这些结果的钠加钾的共转运模型，这是由高渗或去甲肾上腺素激活。当任一离子不存在于孵育介质中时，系统促进共离子进入细胞的交换-扩散类型的移动。在没有外部钾的情况下，钾从细胞中的净移动导致钠逆其电化学梯度的耦合挤出。
Catecholamines induce net salt and water movements in duck red cells incubated in isotonic solutions. The rate of this response is approximately three times greater than a comparable effect observed in 400 mosmol hypertonic solutions in the absence of hormone (W.F. Schmidt and T. J. McManus. 1977 a.J. Gen. Physiol. 70:59-79. Otherwise, these two systems share a great many similarities. In both cases, net water and salt movements have a marked dependence on external cation concentrations, are sensitive to furosemide and insensitive to ouabain, and allow the substitution of rubidium for external potassium. In the presence of ouabain, but the absence of external potassium (or rubidium), a furosemide-sensitive net extrusion of sodium against a large electrochemical gradient can be demonstrated. When norepinephrine-treated cells are incubated with ouabain and sufficient external sodium, the furosemide-sensitive, unidirectional influxes of both sodium and rubidium are half- maximally saturated at similar rubidium concentrations; with saturating external rubidium, the same fluxes are half-maximal at comparable levels of external sodium. In the absence of sodium, a catecholamine-stimulated, furosemide-sensitive influx of rubidium persists. In the absence of rubidium, a similar but smaller component of sodium influx can be seen. We interpret these results in terms of a cotransport model for sodium plus potassium which is activated by hypertonicity or norepinephrine. When either ion is absent from the incubation medium, the system promotes an exchange-diffusion type of movement of the co-ion into the cells. In the absence of external potassium, net movement of potassium out of the cell leads to a coupled extrusion of sodium against its electrochemical gradient.