Key Points
- To examine the spatial and temporal patterns of intracellular calcium concentration during electrically stimulated contractions in atrial and ventricular heart cells.
- Monitored intracellular calcium transients in fluo 3-AM-loaded rat ventricular and guinea pig atrial myocytes using confocal microscopy in whole-cell, regional, and line-scan configurations.
- Evaluated the impact of electrical field stimulation and L-type calcium channel inhibition using 5 µM nifedipine on calcium propagation.
- Rat ventricular myocytes exhibited spatially uniform, synchronous calcium increases across the cell upon stimulation, but displayed focal, nonuniform rises during calcium channel blockade with 5 µM nifedipine.
- Guinea pig atrial myocytes showed peripheral calcium transients that led the central increase by 34 ± 4 ms (mean ± SE, n = 3) before propagating inward.
Structured PICO
PPopulationRat ventricular and guinea pig atrial myocytes loaded with fluo 3-AM
IInterventionElectrical stimulation (with and without Ca2+ channel blockade by 5 microM nifedipine)
OOutcomeSpatial and temporal changes of intracellular calcium ion concentration ([Ca2+]i)surrogate
The t-tubular network ensures synchronous increases of intracellular calcium throughout the cell during an action potential, whereas its absence or calcium channel blockade results in focal, nonuniform increases.