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.


METHODS
Colonic tissue obtained from 14 healthy dogs.


METHODS
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 micromol/L), atropine (1 micromol/L), ryanodine (10 micromol/L), nifedipine (1 micromol/L), ethylene glycol-bis (beta-aminoethylether)-N,N,N',N'-tetra-acetate (EGTA; 0.1 mmol/L), or an extracellular calcium-depleted (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 x 10(4) N/m2) in colonic longitudinal smooth muscle. Maximal responses to butyrate and propionate (50 mmol/L) were 37 and 23%, respectively, of the maximal AMCh response. Acetate was least effective in stimulating contractile responses. Tetrodotoxin and atropine did not affect SCFA-induced contractions. Nifedipine and zero extracellular calcium solution abolished responses to butyrate and propionate, whereas EGTA attenuated (> 60%) but did not abolish those responses. Ryanodine did not affect SCFA-induced contractile responses. The SCFA did not affect colonic circular smooth muscle. CONCLUSIONS AND CLINICAL RESPONSE: The SCFA stimulate longitudinal but not circular colonic smooth muscle contractions via a direct effect on smooth muscle. The mechanism of the SCFA effect appears to involve the influx of extracellular calcium. These findings may account for some of the effects of fiber on canine colonic motility [corrected].
Mcmanus
Catherine M
CM
Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104-6010, USA.
Michel
Kathryn E
KE
Simon
Daniel M
DM
Washabau
Robert J
RJ
D019342:Acetic Acid / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002087:Butyrates / Q000494:pharmacology; D002794:Choline / Q000031:analogs & derivatives* / Q000494:pharmacology; D003106:Colon / Q000187:drug effects*; D004043:Dietary Fiber / Q000378:metabolism; D004285:Dogs; D004533:Egtazic Acid / Q000494:pharmacology; D005227:Fatty Acids / Q000494:pharmacology*; D005260:Female; D005285:Fermentation; D005769:Gastrointestinal Motility / Q000187:drug effects*; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects*; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D011422:Propionates / Q000494:pharmacology; D012433:Ryanodine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D002087:Butyrates; D004043:Dietary Fiber; D005227:Fatty Acids; D011422:Propionates; D012433:Ryanodine; C016197:acetylmonoethylcholine; D013779:Tetrodotoxin; D004533:Egtazic Acid; D001285:Atropine; D009543:Nifedipine; C029658:propionic acid; D002794:Choline; D019342:Acetic Acid