Evaluation of a short-time, oxygen carrier-free perfusion model in rat liver: mitochondrial energy metabolism and insulin effect.

Livers of rats fasted for 18 hr were perfused for 60 min at 37, 35, and 32 degrees C in a simple noncirculating system with a carbogen (95%, 5% CO2) equilibrated, oxygen carrier-free, glucose-containing (200 mg X dl-1) cristalloid perfusate (pH 7.4, 280 mosmol X kg-1) without or with the addition of insulin (10 U X hr-1), and analyzed for tissue ATP, ADP, AMP, acetoacetate, and beta-hydroxybutyrate as well as for parameters of the energy metabolism of isolated mitochondria. Perfusion without insulin at 37 degrees C caused significant alterations: ATP and total adenine nucleotides (TAN) dropped to 62 and 74% of the control values (3.33 and 4.57 mumol X g-1), respectively. The energy charge potential ECP decreased from 0.842 to 0.713. Also, the mitochondrial phosphorylation rate (PR), the respiratory control ratio (RC), and the state 3 respiration rate (ST 3) were significantly depressed to 62, 54, and 72% of the control values. Perfusion with insulin maintained a normal metabolic pattern: ATP 105%, TAN 97%, ECP 0.877, PR 94%, RC 69%, and ST 3 105%. The metabolic deterioration during insulin-free perfusion was decreased at 35/32 degrees C: ATP 67/82%, PR 72/95%, RC 74/87%. At 35 degrees C, insulin ameliorated the metabolic pattern, but normal ranges were no longer reached. At 32 degrees C, insulin had no effect.