Cytochemical determination of acid phosphatase activity in isolated rat hepatocytes during starvation-induced proteolysis

Summary Acid phosphatase activity in isolated rat liver parenchymal cells has been investigated with quantitative histochemical means during short-term starvation, which leads to a considerable loss in protein mass in the parenchyma. Animals trained to a meal-feeding regime in which food was available during 1 h only per 24 h (using an automatic food dispensing machine), were sacrified 6, 12, 18, 24 and 36 h after food had been withheld at the time point (23.00 h) of meal feeding. Acid phosphatase activity was analysed cytophotometrically in isolated hepatocytes incorporated into polyacrylamide gels before the enzyme reaction technique with the post-azo coupling was carried out. No indication could be found for any significant changes in the amount of acid phosphatase activity per individual hepatocyte during the entire period of fasting, as compared with two time points (11.00 and 23.00 h) before the theoretical onset of fasting. It is concluded that the considerable enhancement of protein degradation in the lysosomal apparatus during fasting is not reflected by changes in the cellular acid phosphatase activity.