[Glutamine synthetase and glutaminase activity in the brain and liver homogenates and subcellular fractions of rats with alloxan diabetes (3)].

Abstract

Glutaminsynthetase activity has been determined in microsomal and soluble fractions of brain and liver of normal and alloxan diabetic rats and glutaminase activity in homogenates and mitochondrial fractions. The results obtained indicate that in brain of diabetic animals glutaminesynthetase activity of microsomal fractions is changed very slightly while that of the soluble fraction is marked reduced. In liver tissue enzyme activity is significantly decreased in both microsomal and soluble fractions. In homogenates of brain tissue of diabetic animals glutaminase does not differ markedly from that of control animals both in the presence and absence of activators (phosphate, aspartate, bicarbonate). In homogenates of liver, in the absence of activators, glutaminase activity is greater in diabetic animals than in controls, it is not much changed in the presence of phosphate and decreases in the presence of bicarbonate and aspartate. In diabetic animals, in the presence of phosphate, glutaminase activity of brain mitochondrial fractions increases while that of liver mitochondrial fractions does not change. It is interesting to note that in the absence of activators glutaminase activity is absent in both brain and liver mitochondria while it is quite high in homogenates.