Key Points
- To assess how tissue discontinuities affect impulse propagation in anisotropic monolayers of neonatal rat myocytes.
- Used optical mapping with a voltage-sensitive dye (RH-327) and photodiode array for measuring activation spread.
- Studied four types of cellular structures, including dense cultures and those with varying cleft sizes and nonmyocyte inclusions.
- Correlated activation maps with immunostaining of gap junction protein connexin43 (Cx43).
- In dense monolayers, activation spread remained continuous but had microinhomogeneities, with a Vmax that increased at cleft borders.
- Long intercellular clefts led to discontinuous propagation, significantly decreasing conduction velocity and Vmax at narrow isthmuses.
- Localization of Cx43 inhomogeneity correlated with conduction block and changes in Vmax.
Structured PICO
PPopulationTwo-dimensional anisotropic monolayers of neonatal rat myocytes cultured on a growth-directing substrate of collagen
IInterventionAssessment of activation spread and distribution of maximal upstroke rate of rise (Vmax) using high-resolution optical mapping with a voltage-sensitive fluorescent dye (RH-327) and a 10x10 photodiode array
OOutcomeActivation spread and distribution of maximal upstroke rate of rise (Vmax) of the action potentialsurrogate
Cellular structure and gap junction distribution directly correlate with action potential propagation, suggesting that connective tissue or inhomogeneous connexin distribution may represent predilective sites for conduction block.