Figure 7. SNAP or db-cGMP are unable to inhibit the caffeine-induced Cl⁻ current.

A, actual traces of caffeine-induced currents. SNAP was added in the bath 10 min before application of CCh. B, actual traces of caffeine-induced currents in the absence (continuous curve) and presence of db-cGMP (bold dotted curve) or db-cGMP plus Rp-8-pCPT-cGMPS (dotted curve). C, summary of experiments as shown in A and B. Vertical axis shows the amplitude of I_CCh in the presence of the drugs normalized to their controls. Asterisk indicates a significant difference evaluated by Student's paired t test (P < 0.05). Caf and IP₃ indicate inward currents activated by 10 mM caffeine or photolytically released IP₃, respectively.