Fig. 1

Control of basal I _Ca,L by β-AR-PKA signaling cascade in FVMs. a During the periods indicated by the horizontal lines, the cell was exposed to ACh or/and ISO. Each symbol represents the peak amplitude of I _Ca,L obtained by depolarizing the cell every 8 s–0 mV over a period of 200 ms from a holding potential of −80 mV. The current traces shown in the inset were recorded at the times indicated by the corresponding letters on the main graphs. b Bar graphs representing the average effect of ISO, alone and together with ACh, on I _Ca,L. c After stimulation of I _Ca,L with ISO, the intracellular solution was changed to one containing 20 µM PKI(15-22), which perfused the cell throughout the rest of experiment. d Bar graphs representing the average effect of ISO, alone and together with PKI(15-22), on I _Ca,L. e IBMX (100 µM) alone has no effect but remarkably potentiates the ISO-preactivated I _Ca,L. f Bar graphs representing the average effects of IBMX and ISO, alone and together, on I _Ca,L. *p < 0.05, **p < 0.01, ***p < 0.005, compared with basal I _Ca,L or between indicated groups