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
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. I–C 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). I–C 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). I–C correlation was significantly positive, but weak in IK(Ach)CONST (r = 0.42), and virtually missing in Ito (r = 0.04). The impaired I–C 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 I–C 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I与C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。我– 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)CONST和I 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)。I – C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,我是令人满意成正比Ç当ř ≥0.6和ķ ≤0.2这是在完成我K1和我K(ACH)ACH([R = 0.84,ķ = 0.20,和- [R = 0.61,ķ = 0.06,分别地)。I – C相关性显着为正,但在I K(Ach)CONST中较弱(r = 0.42),而在I to(r = 0.04)中几乎缺失。受损的我- Ç比例在我K(ACH)CONST和我到可能反映了通道表达的异质性。我们得出结论,当不存在I – C比例时,应避免将I转换为J。否则,可能会严重误解数据。