Na/K pump current in guinea pig cardiac myocytes and the effect of Na leak.
Na/K pump current in guinea pig cardiac myocytes and the effect of Na leak.
复制标题
豚鼠心肌细胞Na/K泵电流和Na泄漏的影响。
DOI：
10.1111/j.1540-8167.1997.tb00834.x
复制
发表时间：
1997
影响因子：
2.7
通讯作者：
Stimers,JR
中科院分区：
文献类型：
--
作者：
Dobretsov,M;Stimers,JR
Na/K泵电流。简介：研究了成年豚鼠心室肌细胞稳态Na/K泵电流（Ip），以确定跨膜Na泄漏、膜电位和移液器Na浓度对Na/K泵的影响。方法和结果：使用传统的全细胞膜片钳技术，在大多数其他膜电流被抑制的情况下，ip1被鉴定为K0敏感或瓦巴因敏感电流。对照实验表明，在我们的实验条件下，除了i外，没有K0敏感电流。结果发现，它与其他报道的相似，在- 130和0 mV之间具有电压依赖性，并且在28mm内具有一半的最大激活。还测量了瓦巴因敏感性，发现有两个结合位点，高亲和力位点占总数的5%至10%，其表观亲和力比低亲和力位点高1000倍。当钠浓度从10 mM增加到85 mM时，这两个位点的表观亲和力变化了约10倍（更高的亲和力）。当内灌注0 Na溶液时，发现Na通过膜的泄漏与Na/K泵活性呈线性相关。与之前的假设相反，当跨膜Na梯度较大时，ipa与串联电阻不相关。结论：这些数据表明，在高跨膜Na梯度条件下，Na通过膜泄漏对Na/K泵活性有重要影响。
Na/K Pump Current.Introduction: Steady‐State Na/K pump current (Ip) in adult guinea pig ventricular myocytes was studied to determine the effect on the Na/K pump of transmembrane Na leak, membrane potential, and pipette Na concentration.Methods and Results: Using conventional whole cell, patch clamp techniques, Ipwas identified as either K0‐sensitive or ouabain‐sensitive current when most other membrane currents were inhibited. Control experiments showed that there were no K0‐sensitive currents other than Ipunder the conditions of our experiments. Ipwas found to be similar to that reported by others being voltage dependent between −130 and 0 mV and having a half maximal activation hy Naiof 28 mM. Ouabain sensitivity was also measured, and it was found that there were two binding sites with the high affinity site comprising 5% to 10% of the total and having an apparent affinity 1000‐fold higher than the low affinity site. Apparent affinity of both sites was shifted about 10‐fold (higher affinity) by increasing Naifrom 10 to 85 mM. When internally perfused with 0 Na solution, Na leak through the membrane was found to be linearly related to Na/K pump activity. In contrast to prior suggestions, Ipwas not correlated with series resistance when there was a large transmembrane Na gradient.Conclusion: These data suggest that, under conditions of high transmembrane Na gradient, Na leak through the membrane plays a significant role in determining Na/K pump activity.