The study provides mechanistic insights into how the organization of the T-tubular system influences extracellularly recorded action potential waveforms in rat cardiomyocytes.
Rat cardiomyocyte AP differences warrant no clinical extrapolation; leaves open structural determinants in human models.
Action potentials (APs) were recorded extracellularly from ventricular and atrial cardiomyocytes using isolated rat heart preparations and narrow-tipped (5-µm O.D.) recording pipettes. The negative phase of the AP waveform in ventricular cardiomyocytes exhibited a prolonged and, in about 60% of records, double-peak AP deflection, while that of APs in atrial cardiomyocytes regularly consisted of a single and relatively short peak. Confocal imaging and Monte-Carlo simulations suggest a stochastic variation in the number of t-tubule mouths under the lumen of randomly positioned extracellular recording pipette as the leading determinant of both, between and within, ventricular/atrial AP waveform variations.
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Кубасов et al. (2020) studied this question.
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