Aldehyde dehydrogenase-dependent acetaldehyde metabolism in periportal and pericentral regions of the perfused rat liver.

NADH fluorescence (366 leads to 450 nm) was measured with a large tipped light guide from the surface of rat liver perfused with hemoglobin-free medium without recirculation. A good correlation (r = 0.93) was found between the increase in NADH fluorescence and the rate of oxidation of infused acetaldehyde (0.1-4.0 mM). By using microlight guides placed on either periportal or pericentral areas of the liver, it was found that infusion of acetaldehyde increased NADH fluorescence first in periportal regions and then in pericentral areas. During retrograde perfusions, NADH fluorescence in pericentral areas increased before portal areas. By using the correlation between the increase in NADH fluorescence and the rate of acetaldehyde uptake established with the large light guide, rates of acetaldehyde uptake in pericentral and periportal areas were estimated from the microlight guide measurement of the periportal and pericentral NADH fluorescence increments caused by acetaldehyde infusions. Half-maximal acetaldehyde uptake was observed at about 0.8 mM in both regions. Maximal rates of acetaldehyde uptake were 212 and 197 mumol/g/hr in periportal and pericentral regions, respectively. The results indicate that rates of aldehyde dehydrogenase-dependent acetaldehyde oxidation are similar in periportal and pericentral regions of the liver lobule.