METABOLISM OF RAT-LIVER CELLS DURING INCU BATION IN COLD UW SOLUTION

Simple cold storage of livers for transplantation activates glycolysis due to lack of oxygen. Energy derived from glycolysis may be critical for cell survival and liver cell death may occur once glycolysis is i nhibited in the liver due to accumulation of end products or lack of s ubstrates (glycogen). The relationship between cell death (lactate deh ydrogenase, LDH release). anaerobic glycolysis (lactate production), a nd glycogen content of liver tissue was studied during cold incubation of liver slices in UW solution. Rat livers slices from male Sprague D awley rats were incubated at 4 degrees C in UW solution, with continuo us gentle shaking, under conditions of chemical hypoxia (KCN, 5 mM). T he rate of lactate production, LDH release, ATP and glycogen content w ere measured spectrophotometrically and by HPLC. Lactate increased nea rly linearly for the first 45 h of incubation: total lactate which had accumulated after 48 h was 33.9+/-0.81 mu mol/g and at 96 h nearly th e same, 31.3+/-1.2 mu mol/g. Glycolysis stopped, apparently, because o f the depletion of liver slice glycogen which was initially 238.8+/-1. 7 mu mol/g wet wt. It decreased to 34.7+/-2.7 mu mol/g at 48 h and to 18.7+/-1.1 mu mol/g at 72 h and remained at this level for the next 24 h. An increased leakage of LDH occurred once glycogen metabolism land accumulation) ceased. LDH release could be stimulated after only a fe w hours of cold incubation of liver tissue slices by adding glycolysis inhibitor (iodoacetic acid) to the medium. After 24 h, LDH release wa s 24.4+/-1.8% and increased to 52.8+/-5.2% (P<0.05, Student's t-test) with iodoacetic acid. Adding a glycolytic substrate (fructose, 10 mM) to the medium maintained lactate production for 96 h. The Stimulation of glycolysis by fructose also reduced cell death: LDH release was sig nificantly lower at 72- and 96-h incubation (P<0.001, two-way ANOVA). The ATP content was significantly higher with fructose (P<0.001). Addi ng glucose (20 mM) and fructose (10 mM) in combination resulted in pro longed cell survival, significantly delayed glycogen depletion and sig nificantly higher ATP content at 48 and 72 h (two-way ANOVA). Livers f rom rats who had fasted for 24 h demonstrated the same LDH release at 48 h when incubated with glucose (20 mM) and fructose (10 mM). In conc lusion, LDH leakage from hypoxic cold-stored liver slices is related t o anaerobic glycolysis. Anaerobic glycolysis appears to continue slowl y under hypothermia and provides sufficient energy for maintenance of cell viability. A stimulation of glycolysis in the cold is possible by fructose and results in prolonged cell survival under hypothermic con ditions. Glyco gen depletion can be slowed down by combining glucose a nd fructose.