课题基金 / 基金详情

VOLTAGE-CLAMP STUDIES OF SODIUM PUMP CURRENT AND FLUX

VOLTAGE-CLAMP STUDIES OF SODIUM PUMP CURRENT AND FLUX
钠泵电流和通量的电压钳研究
批准号:
3405877
负责人:
ROBERT F RAKOWSKI
金额:
$20.66万
依托单位国家:
美国
项目类别:
财政年份:
1985
资助国家:
美国
项目状态:
已结题
起止时间:
1985-05-01 至 1994-04-30

项目摘要

项目成果

ROBERT F RAKOWSKI的其他基金

相似基金

相关文献

中文摘要
翻译
该项目的目标是更好地了解 Na/K泵的反应循环中的电压依赖性步骤。 四 具体目的是:1)测量稳态Na/K泵电流-电压 泵操作的各种生电模式的关系(I-Vs),2) 测试Na/K泵的化学计量是否固定在3 Na/2K, 在宽范围条件下与电压无关,3)研究瞬态 Na/K泵电流(泵电荷移动),以及4)测试泵- 介导的Na/Na交换虽然是电中性的,但却是电压依赖性的。 到 实现这些目标,同时测量泵介导的 暴露于可逆泵抑制剂产生的电流和通量 二氢洋地黄毒苷(H2 DTG),将在电压钳位,内部- 透析了鱿鱼的巨大轴突 对照实验已经证明 结果表明:1)H2 DTG对离子电导没有直接影响; 2)电流和 22 Na流出来自同一膜面积; 3)被动钾离子浓度的变化 电流,由于细胞外[K]的变化停止泵,是 钾通道阻断剂在很大程度上阻止; 4)泵介导的Na/Na 通过添加高[ATP]和磷酸盐, 磷酸烯醇丙酮酸和磷酸精氨酸。 稳住- 用于泵操作的正向和反向模式的状态Na/K泵I-Vs 将在各种条件下获得, 在暴露于H2 DTG之前和期间测量膜I-Vs。 的 可以研究Na/K泵的化学计量,因为适当的 控制实验表明,H2 DTG敏感通量和电流可以 等同于Na/K泵通量和电流,因此用于计算 Na与K传输的比率,前提是泵不传输其他离子。 瞬态泵电流的初步测量已在 电压钳爪蟾卵母细胞在没有外部K, 可能将泵限制于Na/Na交换。 一个这样的预测 测量,泵介导的电中性Na/Na交换是电压- 依赖,可以通过评估电压依赖性在鱿鱼轴突中进行测试 从高[ADP]轴突到无钾海水的H2 DTG敏感的Na流出。 进一步了解动物细胞的Na/K泵是重要的,因为 它保持了钠的电化学梯度,这对于 兴奋性和钠耦合运输过程。
英文摘要
The objective of this project is to obtain a greater understanding of the voltage dependent step(s) in the reaction cycle of the Na/K pump. Four specific aims are: 1) measure steady-state Na/K pump current-voltage relationships (I-Vs) for various electrogenic modes of pump operation, 2) test whether the stoichiometry of the Na/K pump is fixed at 3Na/2K and is voltage-independent over wide-ranging conditions, 3) investigate transient Na/K pump currents (pump charge movement), and 4) test whether pump- mediated Na/Na exchange, though electroneutral, is voltage-dependent. To achieve these aims, simultaneous measurements of changes in pump-mediated current and flux, produced by exposure to the reversible pump inhibitor dihydrodigitoxigenin (H2DTG), will be made in voltage-clamped, internally- dialyzed squid giant axons. Control experiments have already demonstrated that: 1) H2DTG has no direct effect on ionic conductances; 2) current and 22Na efflux derive from the same membrane area; 3) changes in passive K current, due to changes of extracellular [K] on stopping the pump, are largely prevented by K channel-blocking agents; 4) pump-mediated Na/Na exchange has been minimized by adding high [ATP] and the phosphagens phosphoenolpyruvate and phosphoarginine, to the dialysis fluid. Steady- state Na/K pump I-Vs for the forward and reverse modes of pump operation will be obtained under various conditions as the difference between membrane I-Vs measured before and during exposure to H2DTG. The stoichiometry of the Na/K pump can be investigated since appropriate control experiments have shown that H2DTG-sensitive flux and current can be equated with Na/K pump flux and current, and thus used to calculate the ratio of Na to K transport, provided the pump transports no other ion. Preliminary measurements of transient pump currents have been made in voltage-clamped Xenopus oocytes in the absence of external K, which presumably limits the pump to Na/Na exchange. A prediction from such measurements, that pump-mediated electroneutral Na/Na exchange is voltage- dependent, can be tested in squid axons by assessing the voltage dependence of H2DTG-sensitive Na efflux from high-[ADP] axons into K-free seawater. Further understanding of the Na/K pump of animal cells is important since it maintains the Na electrochemical gradient which is essential for excitability and for Na-coupled transport processes.
期刊论文(0)
专著(0)
科研奖励(0)
会议论文
SMALL INSTRUMENTATION PROGRAM
VOLTAGE CLAMP STUDIES OF SODIUM PUMP CURRENT AND FLUX
VOLTAGE CLAMP STUDIES OF SODIUM PUMP CURRENT AND FLUX
INVESTIGATION OF GATING CURRENTS IN SKELETAL MUSCLE
海外基金