OXYGEN-FREE RADICAL FORMATION BY RAT HEPATOCYTES DURING POSTANOXIC REOXYGENATION - SCAVENGING EFFECT OF ALBUMIN

Oxygen free radical formation by rat hepatocytes during postanoxic reo xygenation: scavenging effect of albumin. Am. J. Physiol. 266 (Gastroi ntest. Liver Physiol. 29): G451-G458, 1994. - Free radical formation a nd reoxygenation injury were studied in rat hepatocytes perfused with Krebs-Henseleit bicarbonate buffer containing 1% or no albumin. After 2, 2.5, or 3 h of anoxia followed by 1 h reoxygenation in the absence of albumin, free radical formation assessed by low-level chemiluminesc ence and cell injury measured by lactate dehydrogenase (LDH) release a nd by trypan blue uptake increased proportionately. Chemiluminescence increased 4- to 7-fold, LDH release and trypan blue uptake increased 1 .5- to 2-fold, compared with the end of anoxia. With 1% albumin, there was no increase in free radical formation during reoxygenation, and L DH release returned to control levels. There was a linear relation bet ween the increase in chemiluminescence and the rise in LDH release (r( 2) = 0.83) and the increase in trypan blue uptake (r(2) = 0.80), sugge sting that free radical formation during reoxygenation is responsible for the cell injury. These experiments demonstrate that freshly isolat ed hepatocytes produce oxygen free radicals detectable by low-level ch emiluminescence and that reoxygenation injury occurs after a relativel y short period of anoxia (2-3 h). Albumin acts as a free radical scave nger, suppresses the release of reactive oxygen species, and significa ntly reduces reoxygenation injury.