Figure 1.

Effects of db-cAMP (1 mM) on I_Ba using conventional whole-cell recording from an isolated gastric antral myocyte. The upper four traces show (a) inward currents, elicited by voltage steps in control solution ((a) (i)), after the application of db-cAMP ((a) (ii)), following washout of db-cAMP ((a) (iii)) and in the presence of nifedipine ((a) (iv)). The cell capacitance was 51 pF. (b) The time course of inhibition of the peak amplitude of I_Ba by db-cAMP (1 mM) is shown. Time 0 indicates the time when db-cAMP was applied. The inhibition produced by db-cAMP was not reversed by washing with drug-free solution. The application of 10 μM nifedipine inhibited most of the db-cAMP-resistant current. The nifedipine-resistant current was suppressed by Cd²⁺ (100 μM). In each experiment, inward currents were elicited by voltage steps (1 s duration) to +10 mV from a holding potential of −70 mV every 20 s.