Influence of dietary fiber consumption on oxidative metabolism and anaplerotic flux in isolated rat colonocytes.
Colonic fermentation of dietary fiber produces short-chain fatty acids which are energetic substrates for colonocytes. A high-fiber diet may lead to adaptations in colonocyte energy utilization, product formation and anaplerotic fluxes. For 2 weeks, Sprague-Dawley rats consumed diets containing 0, 150 or 300 g/kg fiber in place of digestible carbohydrate. Colonocytes were isolated; substrate oxidation and anaplerotic flux were measured. Glutamine oxidation was higher and glutamate formation was lower with increasing levels of fiber. Glucose, propionate and butyrate oxidation were not altered by diet. ATP yield from glutamine was higher in fiber-fed rats, but ATP from propionate, butyrate and glucose were not affected by the diets. Assessment of anaplerotic flux using the CO2 ratios method revealed no changes attributable to diet. The amount by which CO2 production is greater from C-1 vs C-2 of short-chain fatty acids in this system was established to be approximately 2-fold. Colonocytes use fuels in the preferential order of: glucose & butyrate > > propionate & glutamine. Because differences attributable to diet do not lead to physiologically significant alterations in anaplerotic flux or ATP yield, only minor adaptations of colonocyte oxidative metabolism occur after 2 weeks of consuming a high fiber diet.
Marsman
K E
KE
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
McBurney
M I
MI
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001224:Aspartic Acid / Q000096:biosynthesis; D002245:Carbon Dioxide / Q000378:metabolism*; D002952:Citric Acid Cycle / Q000187:drug effects; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D004032:Diet; D004043:Dietary Fiber / Q000494:pharmacology*; D004435:Eating / Q000502:physiology; D005227:Fatty Acids / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D018698:Glutamic Acid / Q000096:biosynthesis; D066298:In Vitro Techniques; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004043:Dietary Fiber; D005227:Fatty Acids; D002245:Carbon Dioxide; D001224:Aspartic Acid; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D005947:Glucose