Effect of short-chain fatty acids on contraction of smooth muscle in the canine colon

Objective—To determine effects of short-chain fatty acids (SCFA) on canine colonic smooth muscle. Sample Population—Colonic tissue obtained from 14 healthy dogs. Procedure—Short-chain fatty acid (SCFA; acetate, propionate, and butyrate; 1 to 100 mmol/L)-induced contractions were compared with responses obtained with acetylmethylcholine (AMCh; 10-4 mol/L). Roles of enteric neurons, cholinergic receptors, calcium stores in the sarcoplasmic reticulum, and extracellular calcium in the SCFA-induced responses were investigated by incubating muscle strips with tetrodotoxin (1 µmol/L), atropine (1 µmol/L), ryanodine (10 µmol/L), nifedipine (1 µmol/L), ethylene glycol-bis (β-aminoethylether)-N,N,N',N'-tetra-acetate (EGTA; 0.1 mmol/L), or an extracellular calciumdepleted (zero extracellular calcium) solution prior to the addition of propionate or butyrate. Results—Incubation with SCFA elicited isometric stress responses (0.25 to 2.15 × 104 N/m2) in colonic longitudinal smooth muscle. Maximal responses to butyrate a...