PACAP-induced depolarizations in hamster submandibular ganglion neurons.
In this study, we have investigated the effects of pituitary adenylate cyclase-activating polypeptide (PACAP) on in vitro hamster submandibular ganglion neurons using the conventional intracellular recording technique. PACAP (10 microM) induced slow depolarizations in approximately 70% of tested cells. PACAP-induced depolarizations were approximately 10 mV in the peak amplitude, and their durations were approximately 10 min. The slow depolarizations were accompanied by a decrease in membrane conductance (gm) at the initial phase and an increase in gm at the peak phase. Membrane input resistance increased by 14.8 +/- 2.2% (mean +/- S.E., max.) of the resting value at the initial phase and decreased by 30.8 +/- 4.3% (max.) at the peak phase. Anodal break spikes were elicited at the initial phase during PACAP-induced depolarization. In one neuron, anodal break spikes were elicited at the peak. Spikes which followed the anodal break spike were also elicited at 4 Hz in the initial phase during the slow depolarizations. The decrease in gm was probably produced by an inhibition of calcium conductance and an inhibition of slow Ca(2+)-activated K+ channels, while the increase in gm might have been produced by an activation of nonselective cation channels. The slow depolarizations by PACAP might be mediated by a membrane-delimited signal transduction cascade involving G protein in the submandibular ganglion neurons.
Suzuki
Takashi
T
Department of Physiology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502, Japan.
Ono
Hirohito
H
Ikegami
Hideaki
H
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects; D006224:Cricetinae; D017097:Electric Impedance; D019204:GTP-Binding Proteins / Q000187:drug effects; D005726:Ganglia, Parasympathetic / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
D015220:Calcium Channels; D007473:Ion Channels; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D019204:GTP-Binding Proteins