Effect of fasting on the biochemical properties of perfused rat liver

Abstract

Livers from rats which had been either fed ad libitum or fasted for 48 hr were perfused with bovine erythrocytes in Krebs-Ringer buffer containing 3% bovine serum albumin, and their function was studied. No difference was noted in the ability of the livers to produce bile. Those from fed rats maintained their initial rate of urea synthesis (1.5 μmol/min) for 60 min, while those from fasted rats maintained this rate for only 20 min. At the end of these periods the livers from both groups of rats synthesized urea at lower rates. Potassium was released into the accellular fraction of the perfusate at a rate of 0.3 μeq/min 60 min after the start of perfusing livers from fed rats and 20 min after the start of perfusing those from fasted rats. Prior to these times, little or no potassium was released. When compared with unperfused controls, perfusion for 3 hr had no effect on the latency and sedimentability of β-glucuronidase or on the sedimentability of acid phosphatase in homogenates of the livers from rats which had been fed ad libitum. There was, however, a small but statistically sigificant decrease in the latency of acid phosphatase. Perfusion of livers from fasted rats resulted in marked and statistically significant falls in the latency and sedimentability of acid phosphatase and in the sedimentability of β-glucuronidase. The fall in the latency of β-glucuronidase was not statistically significant. It was concluded that the livers from rats which had been fasted for 48 hr were less able to tolerate the stress of perfusion in vitro than those from rats which had been fed ad libitum.