Nutritional and gonadal effects on the intra-acinar profiles of low-K_m and high-K_m aldehyde dehydrogenase activity in rat liver

Summary

Total and low-K_m aldehyde dehydrogenase (ALDH) activity was measured in 50–150 ng microdissected liver tissue samples of the entire sinusoidal length. High-K_m ALDH activity was calculated by subtracting the low-K_m ALDH values from the total ALDH activity. Enzyme activity was measured by a microchemical assay, using the oil-well technique with luminometric determination of NADH.

The intra-acinar profiles of high-K_m and low-K_m ALDH activity could be demonstrated graphically for both male and female rats after 84 h of starvation, and after starvation and refeeding for 6 nights. In addition, the ALDH distribution patterns of juvenile, castrated, and castrated and testosterone-treated rats were determined. It could be demonstrated that starvation, and starvation followed by refeeding, lead to changes in enzyme activity which parallel the loss and regain of liver- and body-weight. The nutritional factors do not essentially alter the normal intra-acinar profiles. In juvenile rats, ALDH is lower by 30% in comparison with the controls, but sex-differences in the distribution profiles are not yet present. Castration has no effect on the amount of enzyme activity but the sex specific distribution profiles are less marked. The main effect of testosterone treatment is an elevation of low-K_m ALDH in the perivenous zone. The characteristics of the intra-acinar profiles of high-K_m and low-K_m ALDH activity are discussed with respect to hepatic acetaldehyde oxidation and alcoholic liver damage.