In Vitro Hepatic Gluconeogenesis and Ketogenesis as Affected by Prolonged Ketonemia-Glucosuria and Fasting in Steers

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Abstract
1,3-Butanediol, which caused ketonemia, and phlorizin, which caused glucosuria, were given to 4 steers for 28 days to determine effects of prolonged ketonemia and glucosuria on in vitro hepatic gluconeogenesis and ketogenesis. Treatments were: control ration, control with butanediol plus phlorizin, and fasting for 9 days. Liver slices, obtained by biopsy, were incubated with 14C substrates. Substrate converted to glucose during control, butanediol plus phlorizin and fasting averaged 2.34, 7.21 and 12.00 for propionate; 0.99, 3.80 and 12.26 for lactate; 0.30, 0.76 and 2.20 for Ala and 2.06, 5.37 and 5.78 [.mu.mol/(h .times. g liver), respectively] for glycerol. Omission of Ca2+ eliminated increases of gluconeogenesis caused by butanediol plus phlorizin and by fasting. Ketone bodies, octanoate and bovine serum albumin did not affect glucose production markedly. Stearate inhibited gluconeogenesis during all periods except fasting. Production of .beta.-hydroxybutyrate [.mu.mol/(h .times. g liver), respectively] during control, butanediol plus phlorizin and fasting averaged 2.07, 4.27 and 3.25 from butyrate and 0.06, 0.27 and 0.02 from palmitate. The gluconeogenic capacity of bovine liver was responsive to physiological and nutritional status.

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