Current density as routine parameter for description of ionic membrane current: is it always the best option?
Language English Country England, Great Britain Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
31794822
DOI
10.1016/j.pbiomolbio.2019.11.011
PII: S0079-6107(19)30145-2
Knihovny.cz E-resources
- Keywords
- Current density, Current-capacitance correlation, Current-capacitance proportionality, Ionic current, Normalisation by ratio, Rat cardiomyocyte,
- MeSH
- Acetylcholine chemistry MeSH
- Cell Membrane physiology MeSH
- Electric Capacitance MeSH
- Electrophysiology MeSH
- Genotype MeSH
- Ions MeSH
- Myocytes, Cardiac drug effects MeSH
- Rats MeSH
- Membrane Potentials drug effects MeSH
- Myocardium MeSH
- Rats, Wistar MeSH
- Heart Atria pathology MeSH
- Muscle Cells cytology MeSH
- Models, Theoretical MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Acetylcholine MeSH
- Ions MeSH
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.
References provided by Crossref.org
Cell size induced bias of current density in hypertrophic cardiomyocytes
