One-stage hepatectomy in the dog Daloze, P; Des Rosiers, C; Arnoux, R ...
The Journal of surgical research
48, Številka:
1
Journal Article
Recenzirano
This report describes a technique for total hepatectomy in the dog. The procedure maintains the integrity of the gastrointestinal tract and the pancreas in the normothermic, anesthetized animal. The ...technique involves (i) a mesentericocaval shunt, (ii) a temporary external bypass between the femoral and jugular veins, and (iii) a permanent internal bypass between the abdominal and thoracic inferior vena cava through the tendinous area of the diaphragm. This 60- to 70-min procedure yields a preparation useful for short-term metabolic studies in nonhepatic tissues.
Prelabeled adenine nucleotides were rapidly degraded in freshly isolated rat liver cells incubated with glycerol at concentrations greater than 0.25 mM. Concomitantly, the 14CATP/14CADP and ...14CATP/14CAMP ratios were decreased. There was a transient increase in radioactive IMP, inosine, and hypoxanthine and a constant accumulation of allantoin. Radioactive adenosine also accumulated transiently under certain conditions. The intracellular Pi concentration was decreased. The magnitude of most of these changes was dependent upon the concentration of glycerol. The effects of glycerol were similar to those of fructose. The extent of endogenous adenine nucleotide catabolism was smaller at high Pi concentration, whereas the extent of glycerol-induced catabolism was unaffected. However, less inosine and more hypoxanthine accumulated during glycerol-induced catabolism at high Pi concentration.
Incubation of freshly isolated rat liver cells with glycerol resulted in an initial decrease, followed by an increase in purine synthesis de novo and in PP-ribose-P availability. The magnitude of ...these effects was dependent on the concentration of glycerol; as it increased, the initial period of latency or inhibition was prolonged, and the extent of the subsequent stimulation was greater. The intracellular Pi concentration and the 14CATP/14CADP ratio were also initially decreased in these cells, and they too returned subsequently to normal values. All these changes were similar to those induced by fructose under the same conditions. The increase in PP-ribose-P availability always preceded that in purine synthesis de novo, indicating that, under most circumstances, PP-ribose-P availability is limiting for purine synthesis de novo. Finally, PP-ribose-P synthesis in these cells varied in parallel with the intracellular Pi concentration and with the ATP/ADP and ATP/AMP ratios.
Purine synthesis de novo and its regulation were studied in freshly isolated hepatocytes from fed adult male rats. The cells incorporated 14Cformate mainly into purine ribonucleotides. The immediate ...effect of increasing the concentration of inorganic phosphate in the incubation medium was an increase in 5-phosphoribosyl 1-pyrophosphate (PP-ribose-P) availability and a stimulation of purine synthesis de novo. However, prolonged incubation of cells in 25 mM phosphate resulted in a decreased PP-ribose-P availability and purine synthesis de novo. Methylene blue and phenazine methosulfate decreased PP-ribose-P availability and purine synthesis de novo although they stimulated considerably the pentose phosphate pathway. In contrast, epinephrine and glucagon increased significantly PP-ribose-P availability and purine synthesis de novo, but they did not change the activity of the pentose phosphate pathway. These results show a relationship between PP-ribose-P availability and purine synthesis de novo in rat hepatocytes. They emphasize the complexity of the regulation of PP-ribose-P availability.
