METABOLIC PROPERTIES OF CELLS ISOLATED FROM ADULT MOUSE LIVER.
Suspensions of isolated cells were prepared from mouse livers that had been perfused via the portal vein with a buffered medium containing sucrose. The demonstration of metabolic activities in these cells was found to be critically dependent on the composition of the suspending medium. The cells showed considerable metabolic activity in a simple medium containing 0.06 to 0.20 M sucrose, but did not respire in 0.30 M sucrose medium. Endogenous respiration was greatest when the sucrose concentration of the medium was 0.10 M or lower and was associated with the formation of acetoacetate. The cells oxidized citric acid cycle intermediates, glutamate, lactate, pyruvate, beta-hydroxybutyrate, alpha-glycerophosphate, and fatty acids and synthesized urea from ammonium chloride, but carbohydrate substrates did not stimulate oxygen uptake. Cells incubated in Krebs' phosphate-saline did not respire. The lack of respiration in this medium is thought to be related to increased permeability of the cell membrane with penetration of calcium ions and orthophosphate into the cells causing mitochondrial swelling and destruction. Further evidence for the loss of cellular permeability barriers is provided by the demonstration of leakage of certain soluble enzymes into the preparative media.
Department of Biochemistry, Medical School, University of Otago, Dunedin, New Zealand.
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Berry