Glycerokinase in rat and human adipose tissue: response to hormonal and dietary stimuli

Glycerokinase activity was measured in homogenates of rat and human adipocytes. Human adipocyte glycerokinase activity was not altered by various dietary and hormonal treatments. In contrast, glycerokinase activity in rat adipocytes was decreased by fasting 48 hr and returned toward normal levels after refeeding for 36 hr. This increase in enzyme activity during refeeding was blocked by prior administration of uromycin. Glycerokinase activity was also significantly increased following prolonged incubation of rat adipocytes with dexamethasone in vitro. This stimulation of glycerokinase was further augmented by the simultaneous addition of insulin. Glycerokinase activity in rat and human adipocytes was also dependent on the body weight of the respective tissue donor. Other data presented indicate that glycerokinase is not involved in the "anti-lipolytic" action of insulin. The possible metabolic significance of glycerokinase in adipose tissue is discussed.