Glycerol turnover in the nonpregnant and ketotic pregnant sheep.

BERGMAN, E. N. Glycerol furnouer in the nonpregnant and k&tic pregnant sheep. Am. J. Physiol. 215(4): 865-873. 1968.Labeled glycerol was infused intravenously into three groups of sheep: fed, fasted, and twin-pregnant hypoglycemic and ketotic. The turnover time of the free glycerol pool was rapid in all animals (15-l 8 min). Mean glycerol turnover rates were 0.25 mmole/hr per kg3i4 in fed animals and increased to 0.56 mmole/hr per kg314 after fasting. Ketotic sheep had greatly elevated glycerol turnover rates (O-70-0.96 mmole/hr per kgYj4) together with elevated plasma glycerol and FFA concentrations. The effects of norepinephrine, insulin, and glucose on endogenous glycerol production were studied in additional experiments. Insulin and glucose decreased glycerol production and the plasma concentrations of glycerol, FFA, and ketone bodies during ketosis. Norepinephrine produced opposite effects in the nonpregnant sheep. It is concluded that all of these agents can affect the rate of lipolysis in ruminant adipose tissue rather than only the rate of esterification. In addition, the rates of glycerol turnover for all experiments seemed directly proportional to its concentration in plasma. It is further concluded that glycerol concentrations mainly are a reflection of glycerol production and that utilization, in turn, is mainly dependent on glycerol concentration.