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.
Ikegami
H
H
Department of Physiology, Tokyo Dental College, 1-2-2, Masago, Mihama-ku, Chiba 261-8502, Japan.
Yamada
T
T
Suzuki
T
T
D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001464:Barium / Q000494:pharmacology; D006224:Cricetinae; D017097:Electric Impedance; D005726:Ganglia, Parasympathetic / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D018377:Neurotransmitter Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D011945:Receptors, Angiotensin / Q000187:drug effects; D015222:Sodium Channels / Q000187:drug effects; D013363:Submandibular Gland / Q000294:innervation*
D057911:Angiotensin Receptor Antagonists; D007093:Imidazoles; D018377:Neurotransmitter Agents; D015221:Potassium Channels; D011725:Pyridines; D011945:Receptors, Angiotensin; D015222:Sodium Channels; D000804:Angiotensin II; C073402:PD 123319; D001464:Barium; D019808:Losartan