The zonation of liver and the distribution of fructose 2,6-bisphosphate in rat liver.

Livers of starved rats refed for 2 h were perfused in situ by a modification of the dual digitonin pulse technique of Quistorff and Grunnet (Quistorff, B., and Grunnet, N. (1987) Biochem. J. 243, 87-95). A pulse of digitonin (2 mg/ml) was infused first antegrade through the portal vein followed retrograde through the vena cava, or in reverse order, 13 mg of digitonin per zone. Microscopic examination showed that this procedure permeabilized the periportal and perivenous zones of the liver without overlap, with a narrow unaffected band of hepatocytes between the zones. The distribution pattern between periportal and perivenous zones ratio for alanine transaminase, lactate hydrogenase, fructose-1,6-bisphosphatase, and phosphoenolpyruvate carboxykinase ranged from 1.5 to 3. Glucokinase activity was higher in the perivenous zone (periportal/perivenous ratio of 0.7) and glutamine synthetase was exclusively present in that zone. Fructose 2,6-bisphosphate concentration was nearly equal in the two zones.