title: Neurokinin3 receptor regulation of acetylcholine release from myenteric plexus.
abstract: This study sought to characterize the action of neurokinin B (NKB) and senktide, a selective synthetic agonist for NK3 receptors, on the myenteric plexus of the guinea pig small intestine. Both peptides stimulated a dose-dependent release of [3H]-acetylcholine (ACh). The mean effective dose values were 1 x 10(-9) for NKB and 3 x 10(-11) M for senktide. The action of these two neurokinins was blocked by the removal of Ca2+ and was sensitive to tetrodotoxin. The release of [3H]ACh was antagonized by omega-conotoxin GVIA, implying the involvement of N-type voltage-sensitive calcium channels. Senktide-evoked ACh release was also insensitive to nifedipine or flunarizine but was blocked by diltiazem. Treatment with protein kinase C (PKC) inhibitors (H-7 and polymyxin B) or activators (12-tetradecanoylphorbol 13-acetate and SC-9) failed to alter the NK3 receptor-mediated ACh output. Our data did not support an action mediated via PKC upon the activation of NK3 receptors on myenteric cholinergic neurons.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004789:Enzyme Activation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009197:Myenteric Plexus / Q000378:metabolism*; D015287:Neurokinin B / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D018042:Receptors, Neurokinin-3; D017981:Receptors, Neurotransmitter / Q000378:metabolism / Q000502:physiology*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D010446:Peptide Fragments; D018042:Receptors, Neurokinin-3; D017981:Receptors, Neurotransmitter; C054724:senktide; D013373:Substance P; D013779:Tetrodotoxin; D015287:Neurokinin B; D011493:Protein Kinase C; D000109:Acetylcholine; D002118:Calcium