Divergent estimates of the ratio between Na+-Ca2+ current densities in t-tubular and surface membranes of rat ventricular cardiomyocytes

0542937 - ÚT 2022 RIV GB eng J - Journal Article
Pásek, Michal - Šimurda, J. - Bébarová, M. - Christé, G.
Divergent estimates of the ratio between Na+-Ca2+ current densities in t-tubular and surface membranes of rat ventricular cardiomyocytes.
Journal of Cell Science. Roč. 134, č. 14 (2021), č. článku jcs258228. ISSN 0021-9533. E-ISSN 1477-9137
Institutional support: RVO:61388998
Keywords : cardiac myocyte * t-tubules * Na-Ca exchanger * membrane current density * log-normal distribution * Monte-Carlo simulation
OECD category: 3.5 Other medical sciences
Impact factor: 5.235, year: 2021
Method of publishing: Open access
https://journals.biologists.com/jcs/article-abstract/doi/10.1242/jcs.258228/268958/Divergent-estimates-of-ratio-between-Na-Ca2?redirectedFrom=fulltext

The ratio between Na+-Ca2+ exchange current densities in t-tubular and surface membranes of rat ventricular cardiomyocytes (JNaCa-ratio) estimated from electrophysiological data published to date yields strikingly different values between 1.7 and nearly 40. Possible reasons for such divergence were analysed by Monte-Carlo simulations assuming both normal and log-normal distribution of the measured data. The confidence intervals CI95 of the mean JNaCa-ratios computed from the reported data showed an overlap of values between 1 and 3 and between 0.3 and 4.3 in the case of normal and log-normal distribution, respectively. Further analyses revealed that the published high values likely result from a large scatter of data due to transmural differences in JNaCa, dispersion of cell membrane capacitances and variability in incomplete detubulation. Taking into account the asymmetric distribution of measured data, the reduction of mean current densities after detubulation, and the substantially smaller CI95 of lower values of the mean JNaCa-ratio, the values between 1.6 and 3.2 may be considered as the most accurate estimates. This implies that 40 to 60% of Na+-Ca2+ exchanger is located at the t-tubular membrane of adult rat ventricular cardiomyocytes.
Permanent Link: http://hdl.handle.net/11104/0320266