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Current density as routine parameter for description of ionic membrane current: is it always the best option?
Progress in Biophysics and Molecular Biology ( IF 3.8 ) Pub Date : 2019-11-30 , DOI: 10.1016/j.pbiomolbio.2019.11.011
Roman Kula 1 , Markéta Bébarová 1 , Peter Matejovič 1 , Jiří Šimurda 1 , Michal Pásek 2
Affiliation  

The current density (J) is a parameter routinely used to characterize individual ionic membrane currents. Its evaluation is based on the presumption that the magnitude of whole-cell ionic membrane current (I) is directly proportional to the cell membrane capacitance (C), i.e. I positively and strongly correlates with C and the regression line describing I–C relation intersects the y-axis close to the origin of coordinates. We aimed to prove the presumption in several examples and find whether the conversion of I to J could be always beneficial. IC relation was analysed in several potassium currents, measured in rat atrial myocytes (in inward rectifier currents, IK1, and both the constitutively active and acetylcholine-induced components of acetylcholine-sensitive current, IK(Ach)CONST and IK(Ach)ACH), and in rat ventricular myocytes (transient outward current Ito). IC correlation was estimated by the Pearson coefficient (r). A coefficient (k) was newly suggested describing deviation of the regression intercept from zero in currents with considerable r value. Based on mathematical simulations, I was satisfactorily proportional to C when r ≥ 0.6 and k ≤ 0.2 which was fulfilled in IK1 and IK(Ach)ACH (r = 0.84, k = 0.20, and r = 0.61, k = 0.06, respectively). IC correlation was significantly positive, but weak in IK(Ach)CONST (r = 0.42), and virtually missing in Ito (r = 0.04). The impaired IC proportionality in IK(Ach)CONST and Ito likely reflects heterogeneity of the channel expression. We conclude that the conversion of I to J should be avoided when IC proportionality is absent. Otherwise, serious misinterpretation of data may arise.



中文翻译:

电流密度作为描述离子膜电流的常规参数:是否始终是最佳选择?

电流密度(J)是通常用于表征单个离子膜电流的参数。其评估基于以下假设:全细胞离子膜电流(I)的大小与细胞膜电容(C)成正比,即IC正相关且强相关,并且描述I–C关系的回归线相交该Ÿ -轴接近坐标原点。我们旨在通过几个示例证明这一推定,并发现将I转换为J是否总是有益的。C在大鼠心房肌细胞中测量的几种钾电流(向内整流电流I K1以及乙酰胆碱敏感电流I K(Ach)CONSTI K(Ach)的组成性活性和乙酰胆碱诱导的成分)中分析了这种关系ACH)和大鼠心室肌细胞中(瞬态向外电流I to)。IC相关性通过皮尔逊系数(r)估算。新建议使用系数(k)描述在具有较大r值的电流中回归截距从零的偏差。根据数学模拟,是令人满意成正比Çř  ≥0.6和ķ  ≤0.2这是在完成K1K(ACH)ACH[R  = 0.84,ķ  = 0.20,和- [R  = 0.61,ķ  = 0.06,分别地)。IC相关性显着为正,但在I K(Ach)CONST中较弱(r  = 0.42),而在I tor  = 0.04)中几乎缺失。受损的- Ç比例在K(ACH)CONST可能反映了通道表达的异质性。我们得出结论,当不存在IC比例时,应避免将I转换为J。否则,可能会严重误解数据。

更新日期:2019-11-30
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