Lipolytic activity of renal cortex during ontogenetic development in rats

The lipolytic activity of rat kidney cortex was investigated in newborn and adult rats. Two peaks of lipolytic activity could be detected at pH 5.0 and 8.4, respectively. Lipase activity at pH 5.0 is completely inhibited by 0.2 M sodium fluoride and can be stimulated by norepinephrine (10 micrograms/ml). Full activity is already present in 5-day-old rats. The response to sodium fluoride and norepinephrine is identical in newborn and adult animals. Lipase activity at pH 8.4 is inhibited up to 85% by 0.6 M sodium chloride. Activity is very low in 5-day-old rats and increases during maturation. This lipase can be stimulated by heparin (100 micrograms/ml) by about 10-25% in newborn and adult animals.