title: Release of [3H]norepinephrine from nerves in rat colonic mucosa: effects of norepinephrine and prostaglandin E2.
abstract: Release of [3H]norepinephrine ([3H]NE) from noradrenergic nerves innervating rat colonic mucosa was studied by superfusion of a muscle-stripped preparation of rat colon. After a period of incubation with [3H]NE, the tissue was superfused with different releasing agents. Depolarization of the tissue with a medium containing 50 mM K+ evoked the release of [3H]NE. Veratridine (5 X 10(-5) M) also stimulated the efflux of [3H]NE; this was blocked by tetrodotoxin (2 X 10(-7) M). Tyramine, which releases NE by a nondepolarizing mechanism, also evoked [3H]NE release from the colonic mucosal preparation, and this release was not decreased in the absence of calcium. Exogenous NE (10(-7) M) inhibited the high K+-evoked release by 50% in the presence of desmethylimipramine, a NE uptake inhibitor. In addition, prostaglandin E2 (1 X 10(-7) M) significantly reduced the K+-evoked release to less than 50% of control. Pretreatment with 6-hydroxydopamine, which selectively destroys NE neurons, reduced the K+-evoked release of [3H]NE to 40% of control. This study suggests that colonic mucosa of the rat contains noradrenergic nerves that function in a manner characteristic of the noradrenergic nerves in other tissues.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003106:Colon / Q000294:innervation*; D003891:Desipramine / Q000494:pharmacology; D015232:Dinoprostone; D006892:Hydroxydopamines / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000294:innervation*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism* / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium; D014439:Tyramine / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
chemical_list: D006892:Hydroxydopamines; D011458:Prostaglandins E; D014316:Tritium; D013779:Tetrodotoxin; D014701:Veratridine; D015232:Dinoprostone; D011188:Potassium; D002118:Calcium; D003891:Desipramine; D009638:Norepinephrine; D014439:Tyramine