Inhibitory innervation of cat sphincter of Oddi.
1 Electrical stimulation with trains of 0.1-0.2 ms pulses of the cat isolated sphincter of Oddi inhibited the spontaneous contractile activity and lowered base-line tension considerably. A contraction usually followed the period of stimulation. 2 These inhibitory effects were prevented by tetrodotoxin 0.1-0.5 mug/ml but were not reduced by hexamethonilm, morphine, or blockade of alpha- or beta-adrenoreceptors of cholinoceptors with phenoxy-benzamine propranolol or atropine, respectively. 3 Adenosine-5'-triphosphate (ATP) and adenosine-5'-diphosphate (ADP) inhibited the spontaneous sphincter activity and caused relaxation thus mimicking the effects of the C-terminal octapeptide of cholecystokinin (C8-CCK), isoprenaline and prostaglandin E1 and E2. 4 ATP alone (greater than 100 mug/ml) or ATP (greater than 10 mug/ml) plus dipyridamole (1 mug/ml), relaxed the sphincter to the same degrees as did the field stimulation. 5 In sphincter maximally contracted by acetylcholine, the effect of stimulation was more marked than that recorded in uncontracted preparations. 6 The present findings suggest that the sphincter of Oddi receives inhibitory nerves that are neither cholinergic nor adrenergic.
D000109:Acetylcholine / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D014670:Ampulla of Vater / Q000294:innervation*; D000818:Animals; D002415:Cats; D004347:Drug Interactions; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009803:Sphincter of Oddi / Q000294:innervation* / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology
D013779:Tetrodotoxin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000109:Acetylcholine