Similar Effects of Calcitonin, Insulin and Somatomedin A on Lipolysis and Uptake of Calcium and Glucose in Rat Adipose Tissue In Vitro

Abstract

The effects of calcitonin, insulin and somatomedin A on lipolysis and uptake of calcium and glucose in rat adipose tissue were studied. The three hormones depressed, dose-dependently, the glycerol release during non-stimulated lipolysis but, in the presence of glucose, potentiated the lipolytic response to ACTH and noradrenaline. Since calcitonin and somatomedin A, similar to insulin, increased glucose uptake and oxidation, the latter effect on lipolysis was presumed to be due to an increased reesterification.

In contrast to the adenylate cyclase activating lipolytic hormones, which increase calcium accumulation in the fat tissue, calcitonin as well as insulin and somatomedin A caused a depression of this calcium uptake concomitantly with the effect on lipolysis. It was shown that the inhibition of calcium uptake was not correlated with a diminished free fatty acid pool in the tissue.

It is proposed that calcitonin, insulin and somatomedin A may have common effector mechanisms in their actions as anabolic hormones.

Key words

Calcitonin - Insulin - Somatomedin - Antilipolysis - Lipolysis - Calcium - Glucose