Distribution of pyruvate kinase type L and M2 in microdissected periportal and perivenous rat liver tissue with different dietary states.
Pyruvate kinase type L and M2 activities were measured in microdissected periportal and perivenous liver tissue from rats in different dietary states. A specific antibody against pyruvate kinase type L was used to distinguish the two isoenzymes. Using separated cells it was found that the L-isoenzyme was essentially restricted to the parenchymal and the M2-isoenzyme to the non-parenchymal cells. Pyruvate kinase type L activity in the perivenous zone was about twice as high as in the periportal zone in both male and female fed rats. Starvation for 48 h led to a decrease of the overall activity and to a lower perivenous-periportal gradient. After refeeding for 48 h the overall activity and the gradient were increased to above the normal level. Pyruvate kinase type M2 was homogenously distributed within the liver acinus. After 48 h starvation no change in the overall activity nor in the zonal distribution was observed. Refed rats exhibited a slightly reduced overall activity. Since the hepatocytes contain the total regulatory L- but no M2-pyruvate kinase the heterogeneous distribution of the L-isoenzyme under different dietary states supports the model of metabolic zonation of liver parenchyma with glycolysis predominantly in the perivenous zone.
D000818:Animals; D005260:Female; D005502:Food; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000033:anatomy & histology / Q000201:enzymology*; D008297:Male; D011770:Pyruvate Kinase / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000201:enzymology*
D007527:Isoenzymes; D011770:Pyruvate Kinase