Presynaptic effects of cholecystokinin octapeptide on neuromuscular transmission in the frog.
Intracellular recordings were obtained from the frog sartorius muscle end-plate to investigate the effects of cholecystokinin octapeptide (CCK-8) on cholinergic transmission at the neuromuscular junction. A brief bath-application of CCK-8 (1 microM) produced a depression, followed by a long-lasting facilitation, of the amplitude and the quantal content of the end-plate potential (epp). CCK-8 had a biphasic effect, an initial depression followed by an augmentation of the frequency of the miniature epps. CCK-8 did not affect the sensitivity of the nicotinic receptor at the end-plate. These results suggest a significant role for CCK-8 in cholinergic transmission, possibly as a modulator of the evoked release of acetylcholine from motor nerve terminals.
D000818:Animals; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D011898:Ranidae; D011978:Receptors, Nicotinic / Q000187:drug effects; D012844:Sincalide / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*
D011978:Receptors, Nicotinic; D012844:Sincalide