Activity-dependent changes of slow inward current in ventricular heart muscle.

摘要: 1. The relationships between membrane voltage, contractile force and slow inward current were studied in cat dog papillary muscles or trabeculae employing the double sucrose gap voltage clamp technique. The experiments performed at 30°C preparations stimulated a frequency of 0.5 Hz. 2. The known steady state force, confirmed. 3. Under non-steady conditions decreases during ascending increases descending contraction staircases when steps test train exceed about 60 mV from resting level. Depolarization below produce parallel changes force. Those which increase shift threshold Isi towards more negative values. 4. During an increasing background outward was regularly observed together with diminshing current. 5. The reported transients agree action potential configuration mechanical transients: prolongation plateau corresponds to increase, shortening late repolarization decrease respective ranges. 6. The tentatively separated into two components. main component is inversely proportional it exhibits well current-voltage relationship for this current. other one directly may be related regenerative response reticular membranes.