Slow inward current and action potentials of papillary muscles under non-steady state conditions

摘要: 1. The relationship of the contractile response cat papillary muscles and slow inward current, recorded under voltage clamp conditions (single sucrose gap), has been studied. preparations were driven at a rate 30 per min 31 degrees C. Both variables during train 7 identical depolarizations (for 1 s from resting potential to -15 +40 mV). contractility increased severalfold reached steady state within 5-6 consecutive depolarizations. 2. voltage-dependence current was confirmed: maximum found near 0 mV. On repetition pulses gradually diminished in amplitude more slowly activated inactivated. shift current-voltage curve indicated decrease reversal potential. 3. Under non-steady correlate closely with magnitude any given level depolarization. relation linear negative slope. largest not voltages which elicited current. 4. progressive is significantly affected by inadequate time for recovery changing conductances, since it occurs also stimulation frequency 15 remains virtually unaltered after 20 period quiescence. 5. course total ionic phase 2 action reconstructed family curves obtained as various voltages, respecting contractility-dependence resulting correlated first derivative A general conformity ascertained. 6. correlation configuration indicates that its activation determines depth notch separating spike plateau, plateau inactivation affects repolarization. 7. It concluded described simultaneous changes mechanical electrical phenomena might be due [Ca]i, responsible intense proteins on one hand, decreased driving force carried Ca ions, other.