Angiotensin II-induced depolarizations in hamster submandibular ganglion neurons

Angiotensin II acts as an excitatory neurotransmitter of the sympathetic ganglia. In the parasympathetic neurons, however, angiotensin II (angio II)-induced responses have not been recorded. In this study, we investigated the effects of angio II in the hamster submandibular ganglion (SMG) neurons using a intracellular recording technique. Approximately 70% of these ganglion cells responded with persistent depolarization (3-6 mV, 5-9 min) at a concentration of 10 microM. The angio II-induced depolarizations were caused by the combination of an increase in Na+ conductance and a decrease in K+ conductance. An involvement of K+ channels such as M channels and SK channels in the electrogenesis mechanism was suggested by an inhibitory effect of Ba2+ ion on the component of the increased membrane input resistance during the angio II-induced depolarization. In addition, the angio II-induced depolarizations were mediated through angio II type I (AT1) receptors. Thus angio II is probably a neurotransmitter that increases their excitability in most of the neurons in parasympathetic ganglia.