Metabolic Adaptations in Higher Animals VI. Liver Arginase Activity During Adaptation to High Protein Diet. ∗

Abstract

Summary

1. Liver arginase activity of rats increased within one day when the casein content of their diet was increased from 25% to 45% or 70% whether the results were expressed as activity per liver or per g of liver protein nitrogen. Arginase activity of the group receiving 45% casein continued to increase for 4 days and that of the group receiving 70% casein continued to increase for 7 days. Average liver weight of the high protein groups also increased significantly above that of the 25% casein group. 2. Growth rate and food consumption were depressed for one day when the casein content of the diet was increased to 45%, and for 2 or 3 days when it was increased to 70%; thereafter, growth rates of the 3 groups differed only slightly. 3. When the casein content of the diet was dropped from 70% to 25% and rate of loss of arginase activity was plotted graphically the curve obtained was almost the reverse of that obtained when the casein content of the diet was raised from 25% to 70%. 4. A correlation between total activity of liver arginase and amount of urea in urine was observed throughout 10 days after changing the casein content of the diet from 25% to 70%. 5. Kidney arginase activity and kidney weight also increased when casein content of the diet was raised from 25% to 70%.