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

KULA, Roman, Markéta BÉBAROVÁ, Peter MATEJOVIČ, Jiří ŠIMURDA and Michal PÁSEK. Current density as routine parameter for description of ionic membrane current: is it always the best option? PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD, 2020, vol. 157, NOV 2020, p. 24-32. ISSN 0079-6107. Available from: https://dx.doi.org/10.1016/j.pbiomolbio.2019.11.011.

Basic information

• Original name: Current density as routine parameter for description of ionic membrane current: is it always the best option?
• Authors: KULA, Roman (203 Czech Republic, belonging to the institution), Markéta BÉBAROVÁ (203 Czech Republic, guarantor, belonging to the institution), Peter MATEJOVIČ (203 Czech Republic, belonging to the institution), Jiří ŠIMURDA (203 Czech Republic, belonging to the institution) and Michal PÁSEK (203 Czech Republic, belonging to the institution).
• Edition: PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY, OXFORD, PERGAMON-ELSEVIER SCIENCE LTD, 2020, 0079-6107.

Other information

• Original language: English
• Type of outcome: Article in a journal
• Field of Study: 10608 Biochemistry and molecular biology
• Country of publisher: United Kingdom of Great Britain and Northern Ireland
• Confidentiality degree: is not subject to a state or trade secret
• WWW: URL
• Impact factor: Impact factor: 3.667
• RIV identification code: RIV/00216224:14110/20:00118627
• Organization unit: Faculty of Medicine
• Doi: http://dx.doi.org/10.1016/j.pbiomolbio.2019.11.011
• UT WoS: 000582745400005
• Keywords in English: Ionic current; Current density; Current-capacitance correlation; Current-capacitance proportionality; Rat cardiomyocyte; Normalisation by ratio
• Tags: 14110515, rivok
• Tags: International impact, Reviewed

Abstract

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, I-K1, and both the constitutively active and acetylcholine-induced components of acetylcholine-sensitive current, I-K(Ach)CONST and I-K(Ach)ACH), and in rat ventricular myocytes (transient outward current I-to). 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 I-K1 and I-K(Ach)ACH (r = 0.84, k = 0.20, and r = 0.61, k = 0.06, respectively). IeC correlation was significantly positive, but weak in I-K(Ach)CONST (r = 0.42), and virtually missing in Ito (r = 0.04). The impaired I-C proportionality in I-K(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. (C) 2019 Elsevier Ltd. All rights reserved.

Links

• NV16-30571A, research and development project: Name: Klinický význam a elektrofyziologické zhodnocení mutace c.926C>T genu KCNQ1 (p.T309I) jako možné „founder mutation“ syndromu dlouhého intervalu QT