The regulation of the calcium conductance of cardiac muscle by adrenaline.

The effect of adrenaline on the Ca-dependent slow inward current, Is, of mammalian cardiac muscle has been investigated by the voltage-clamp method. The mechanism of the increase in the conductance, gs, was analysed on the basis of a kinetic scheme (Hodgkin however, the relative decrease of the current amplitude was the same with and without adrenaline. The reversal potential, ER, of Is was not changed by the drug. This indicates that the catecholamine has no influence on the selectivity of these conductance channels. 4. An increase in the number of functional conductance channels by adrenaline is discussed as a possible mechanism for the increase in Gs.