Cyclic AMP-dependent protein kinase-independent angiotensin II-induced inhibition of calcium current in hamster submandibular ganglion neurons.

In a previous study, we demonstrated that angiotensin II (AngII) inhibited voltage-dependent calcium channels (VDCCs) currents (ICa) in hamster submandibular ganglion (SMG) neurons. In sinoatrial node cells, it has been reported that AngII inhibits ICa by suppressing cyclic AMP production. In this study, to investigate the possible involvement of a cyclic AMP-cyclic AMP dependent protein kinase (PKA) pathway in the AngII-induced inhibition of ICa, effects of AngII were examined in SMG neurons after treatment with an activator and inhibitor of PKA. Neither pretreatment of neurons with membrane permeable cyclic AMP nor intracellular dialysis of PKA blocker attenuated the AngII-induced inhibition of ICa. These results indicate that AngII inhibited ICa via a cyclic AMP-PKA-independent mechanism in SMG neurons.