Effect of Periodic Fasting and Refeeding on Rat Kidney Cortex Enzymes, Gluconeogenesis and Water Intake Pattern

Publisher Website
Google Scholar
Abstract
Rats were trained to periodic fasting and refeeding until they could maintain their body weight by eating 1 day out of 3 and some effects of this food intake pattern on their kidneys were studied. The activities of phosphoenolpyruvate carboxykinase (PEPCK) and the soluble pyruvate carboxylase (PC) of the kidney cortex of the trained rats were found to be increased compared to those of ad libitumfed controls. Gluconeogenesis from a mixture of amino acids by the isolated perfused kidneys of trained rats was also increased. In contrast, high fat diets had no effect on pyruvate carboxylase activity in either kidney or liver whereas PEPCK was increased in both organs. High protein diets did not influence PC activity, resulted in increased liver PEPCK to about the same extent as the high fat diet and increased kidney cortex PEPCK to 2.4 times the activity found in rats fed a mixed diet. Thus the pattern of enzyme change found in periodically fasted rats was not reproduced by either of these changes in diet composition. Kidney cortex glutaminase I activity of trained rats was decreased compared to values for ad libitum-fed controls and was thus dissociated from gluconeogenesis. Water intake patterns were studied in rats fed 1 day out of 3 and in those trained to eat for 2 hours a day or on alternate days. Changes in the amount and diurnal rhythm of drinking by all of these rats compared to the pattern found in ad libitum-fed controls are described.