Luminal propionate-induced secretory response in the rat distal colon in vitro.

摘要: 1. The stimulatory action of propionate on colonic electrolyte transport and involvement the enteric reflex in this was studied vitro using an Ussing chamber rat. short-circuit current (Isc) bidirectional fluxes Na+ Cl- were measured. Mucosa-submucosa preparations, containing submucosal nerve, from distal colon used most cases. 2. Mucosal application caused transient increases transmural potential difference, with mucosal side negative, Isc conductance. Serosal acid had no effect. 3. Adaptation response occurred when applied to bathing solution cumulatively without washing out first dose. If tissues washed held more than 20 min before next application, almost completely restored. 4. increase concentration dependent, a 50% effective approximately 7 x 10(-5) M. 5. Two other short-chain fatty acids (SCFAs), n-butyrate n-valerate, but not acetate, increased added solution. 6. Bumetanide (3 M) serosal chloride-free condition, amiloride (10(-4) M), inhibited responses propionate. Propionate-stimulated secretion resulted mainly unidirectional serosal-to-mucosal movement. Propionate did affect flux. 7. Tetrodotoxin (10(-7) somatostatin hexamethonium propionate-evoked by 40, 70 30%, respectively. 8. Atropine (10(-5) also Isc-increase 90%. 9. Pre-treatment (2 min) surface procaine (5 10(-4) 10. results suggest that luminal transiently stimulated chloride secretory is due direct colonocytes, large part release acetylcholine at neuro-colonocyte junctions, probably via involving sensory mechanism, cholinergic motor nerves ganglia.