Effects of anesthetics and starvation on in vivo gluconeogenesis in virgin and pregnant rats.

To study in vivo gluconeogenesis, female virgin rats were injected intravenously with 14C-alanine (ul) and the production of 14C-glucose was determined at two, five, or ten minutes thereafter. At ten minutes the appearance of 14C-glycogen in the liver was also determined. The intraperitoneal injection of sodium pentobarbital (Nembutal) (33 mg/kg body weight) 30 minutes prior the tracer did not affect the rate of gluconeogenesis in fed rats compared with unanesthetized animals, whereas in rats fasted 24 hours it produced a significant enhancement in all parameters studied. A similar effect in enhancing in vivo gluconeogenesis was observed with both pentobarbital or ether anesthesia when 3-14C-pyruvate was used as tracer in virgin rats fasted 24 hours. In contrast to the effect in virgin animals, pentobarbital anesthesia did not modify in vivo gluconeogenesis in either fed or 24-hour fasted 21-day pregnant rats. Ether anesthesia, however, caused an enhancement in 14C-glucose production from 3-14C-pyruvate in 24-hour fasted pregnant rats. On the basis of reported changes in sympathoadrenal activity produced by starvation and pregnancy, present results indicate that the enhancing effects of anesthetics on gluconeogenesis result from their capacity to stimulate adrenal medulla cathecholamine release or tissue sympathetic activity. Our findings also demonstrate that in an investigation of metabolic parameters it cannot be assumed that effects of anesthetics are always of the same degree and direction since they vary with the condition of the experimental subject.