High-resolution microscopic determination of hepatic NADH fluorescence for in vivo monitoring of tissue oxygenation during hemorrhagic shock and resuscitation

Impaired microvascular oxygen supply reduces oxidative phosphorylation and causes an increase in cellular NADH, which was monitored densitometrically in vivo by high-resolution fluorescence microscopy (330-390/>430 nm excitation/emission wavelengths) in rat livers (n = 8) subjected to hemorrhagic shock and resuscitation. At each time point, NADH fluorescence was recorded from 10 different observation fields of the left liver lobe. Withdrawal of a total of 4.5 mi arterial blood for induction of volume-controlled hemorrhagic shade resulted in an increase in NADH fluorescence by similar to 31% from 45.1 +/- 3.9 to 59.2 +/- 4.2 aU, which was associated with a all of arterial blood pressure from 110 +/- 3 to 51 +/- 8 mmHg, a decrease in hepatic tissue oxygenation (flexible polarographic surface electrode) from 18 +/- 2 to 2 +/- I mmHg, and a restriction of hepatic bile flow fi-om 1.7 +/- 0.1 to 0.5 +/- 0.2 mu l/min x g. Normovolemic resuscitation with 10% hydroxyethylstarch failed to completely restore the metabolic state of liver tissue (NADH fluorescence 49.9 +/- 3.1 ati), arterial blood pressure (83 +/- 8 mmHg), hepatic tissue oxygenation (7.4 +/- 1.5 mmHg), and hepatocellular excretory function (1.3 +/- 0.1 mu l/min x g). During both shock and resuscitation, the ratio ber-vc een pericentral and periportal NADH fluorescence intensities slightly increased, but calculation of coefficients of variance of interlobular NADH fluorescence did not reveal an increase in heterogeneity of tissue metabolic state. Significant correlations were found between NADH fluorescence and both hepatic tissue oxygenation (r(2) = 0.78, P < 0.01) and hepatic bile flow (r(2) = 0.85, P < 0.01), indicating that high-resolution intravital microscopic assessment of NADH fluorescence reflects appropriately the relation between local oxygen supply and demand in hepatic tissue in vivo. (C) 1997 Academic Press.