Role of protein kinase C in the excitatory action of cholinergic nerve stimulation on spontaneous activity of circular smooth muscle isolated from the guinea-pig stomach antrum.
Following inhibition of NO production with nitroarginine, circular muscle isolated from the guinea-pig gastric antrum generated periodic slow potentials and unitary potentials. Transmural nerve stimulation (TNS) during the interval between slow potentials evoked an apamin-sensitive inhibitory junction potential (IJP) followed by an atropine-sensitive depolarization; the latter was either a transient depolarization with enhanced generation of unitary potentials or a slow potential. After inhibition of unitary potentials and slow potentials with 1 mM caffeine, TNS evoked an IJP and subsequent cholinergic depolarization, the latter developing slowly and lasting for about 10 s. TNS was unable to elicit a slow potential until a certain period of time had elapsed following the cessation of a slow potential. The period during which TNS could not evoke slow potentials (termed the high-threshold period) was about 10 s, and this period was increased by chelerythrine and decreased by phorbol esters. It is concluded that cholinergic nerve-mediated excitation of gastric muscle involves the activation of protein kinase C (PKC), and that the high-threshold period, during which the generation of slow potentials by TNS is inhibited, may be a consequence of reduced activity of PKC.
Lee
Kyu Pil
KP
Department of Physiology, Nagoya City University Medical School, Mizuho-ku, 467-8601 Nagoya, Japan.
Nakamura
Eri
E
So
Insuk
I
Kim
Ki Whan
KW
Suzuki
Hikaru
H
D000200:Action Potentials / Q000187:drug effects; D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D002110:Caffeine / Q000494:pharmacology; D002799:Cholinergic Fibers / Q000187:drug effects* / Q000201:enzymology; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009130:Muscle, Smooth / Q000201:enzymology / Q000294:innervation*; D009469:Neuromuscular Junction / Q000502:physiology; D019335:Nitroarginine / Q000494:pharmacology*; D010617:Phenanthridines / Q000494:pharmacology; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011706:Pyloric Antrum / Q000201:enzymology / Q000294:innervation
D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D010617:Phenanthridines; D010703:Phorbol Esters; D019335:Nitroarginine; D002110:Caffeine; C016299:chelerythrine; D011493:Protein Kinase C