AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 6 800-G805, Copyright © 1986 by American Physiological Society
O2 uptake in periportal and pericentral regions of liver lobule in perfused liver
T. Matsumura, F. C. Kauffman, H. Meren and R. G. Thurman
O2 uptake by the perfused liver decreased at O2 concentrations considerably
higher than levels that caused NADH reduction when the input O2
concentration was varied. The maximal rate of O2 uptake was two- to
threefold higher in periportal (137 +/- 8 mumol . g-1 . h-1; O2
concentration = 478 +/- 37 microM) than pericentral regions (59 +/- 5 mumol
. g-1 . h-1; O2 concentration = 263 +/- 21 microM); however, the O2
concentration required for half-maximal O2 uptake was similar
(approximately 20 microM) in the two areas. The infusion of atractyloside,
antimycin A, or KCN inhibited O2 uptake in both zones by 50-85%, indicating
that O2 uptake in both regions was largely dependent on mitochondrial
electron transport. The content of ATP and ADP and ATP:ADP were similar in
microdissected samples from periportal and pericentral areas. In contrast,
when livers were perfused in the retrograde direction, O2 uptake was two-
to threefold greater in pericentral than in periportal regions. Maximal
rates of O2 uptake correlated with the local O2 concentration irrespective
of the direction of flow when the electrode was moved across the liver
lobule with a micromanipulator. Lower rates of O2 uptake in pericentral
areas were not altered appreciably by infusion of agents known to uncouple
oxidative phosphorylation (DNP), increase ADP supply (fructose), or
increase the NADH redox state (ethanol or octanoate). These data are
consistent with the hypothesis that maximal rates of O2 uptake are
regulated, in part, in the perfused liver by O2 concentrations far above
the Km of cytochrome oxidase for O2.
