Ruminant hepatic metabolism of volatile fatty acids, lactate and pyruvate.

摘要: Ruminant liver has a quantitatively unique array of substrates presented to it because the extensive fermentation dietary carbohydrate organic acids in gastrointestinal tract. The single largest input energy extrasplanchnic tissues is acetic acid derived from fermentation, which largely unused by hepatic parenchyma. other volatile fatty primarily propionate, are cleared extensively, but not completely, liver. This results marked concentration gradient for these across lobule. L-lactate, tissue metabolism, as well variable amounts rumen used at rate lower than propionate and below predicted capacity based on vitro enzymatic intact cell data. net result this selective utilization peripheral blood containing significant concentrations L-lactate acetate, little acids. Propionate carbon metabolized cells converted glucose with true loss carbon, same lactate carbon. energetic efficiencies may be much less optimal cycling through pyruvate kinase, carboxylase phosphoenolpyruvate carboxykinase. Inhibition futile represent one avenue costs maintenance production can lowered ruminants.