OXIDATIVE ACTIVITY IN MITOCHONDRIA ISOLATED FROM RAT-LIVER AT DIFFERENT STAGES OF DEVELOPMENT

The purpose of this study was to evaluate the oxidative capacities in hepatic mitochondria isolated from prepubertal, young adult and adult rats (40, 90 and 180 days of age, respectively). In these rats, mitoch ondrial respiratory rates using FAD- and NAD-linked substrates as well as mitochondrial protein mass were measured. The results show that on ly the oxidative capacity of FAD-linked pathways significantly decline d in mitochondria from 180-day-old rats compared with those from young er animals. When we consider FAD-linked respiration expressed per g li ver, no significant difference was found among rats of different ages because of an increased mitochondrial protein mass found in 180-day-ol d rats. However, when FAD-linked and lipid-dependent respiratory rates were expressed per 100 g body weight, significant decreases occurred in 180-day-old rats. Therefore, the decrease in liver weight expressed per 100 g body weight rather than an impaired hepatic cellular activi ty may be the cause of body energy deficit in 180-day-old rats. (C) 19 98 John Wiley & Sons, Ltd.