Fig. 3.
Effects of hyperpolarization-activated/cyclic nucleotide-modulated (HCN) channel and PKA inhibitors on forskolin-stimulated calcium influx in non-lineage-specific rat anterior pituitary cells. A: the stimulation of Ca2+ influx by forskolin in cells with HCN channels inhibited by pretreatment with ZD7288, which was applied for 10 min prior to recording. B: the lack of an effect of forskolin on Ca2+ influx after treatment of cells by 10 μM H89, an inhibitor of PKA. Notice the change in the pattern of calcium signaling after addition of H89 (2 top traces). Traces shown are representative of 159 records. C and D: PKA inhibitor Rp-cAMPs did not alter the pattern of spontaneous firing of action potentials (9 of 9 cells; C) but did abolish the 8-Br-cAMP-induced increase in the firing frequency (4 of 4 cells; D). Vm, membrane potential.