Current density as routine parameter for description of ionic membrane current: is it always the best option?

0512117 - ÚT 2021 RIV GB eng J - Článek v odborném periodiku
Kula, R. - Bébarová, M. - Matejovič, P. - Šimurda, J. - Pásek, Michal
Current density as routine parameter for description of ionic membrane current: is it always the best option?
Progress in Biophysics & Molecular Biology. Roč. 157, November (2020), s. 24-32. ISSN 0079-6107. E-ISSN 1873-1732
Institucionální podpora: RVO:61388998
Klíčová slova: cardiac ionic current * current-capacitance correlation * current-capacitance proportionality * current density * rat cardiomyocyte
Obor OECD: Biophysics
Impakt faktor: 3.667, rok: 2020
Způsob publikování: Omezený přístup
https://www.sciencedirect.com/science/article/pii/S0079610719301452?via%3Dihub

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 altered 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.
Trvalý link: http://hdl.handle.net/11104/0315805