Abstract
Effects of starvation and cobalt injection on lipid metabolism were studied in isolated liver cells from three groups of animals; normally fed, starved and starved plus cobalt-treated rats and rabbits.
The nutritional state of the rat has a profound influence on the total conversion of palmitate to fatty acid esters and ketone bodies. Starvation of rats markedly decreased the esterification of palmitate into triglycerides and significantly increased oxidation into ketone bodies. Starvation of rabbits, scarcely affected the esterification and oxidation of added palmitate.
Enhanced esterification of labelled palmitate into triglyceride was shown by isolated liver cells from cobalt-treated rabbits, whereas liver cells from cobalt-treated rats were characterized by increased conversion of added palmitate to phospholipids and by decreased ketogenesis. A marked elevation in blood ketone bodies concentration in starved rabbits and its suppresion by cobalt treatment coincides with the alteration of ketone body formation in liver cells from rats, in which ketogenesis was increased by starvation and suppressed by cobalt treatment.
Cobalt added to the incubation medium did not affect the esterification and oxidation of palmitate in the isolated liver cells from three groups of animals.
Secretion of triglyceride from the isolated liver cells was completely suppressed when cobalt was added to the incubation medium, whereas secretion of acetoacetate from the cells was unaffected by the added cobalt.
These results indicate that cobalt added to the incubation medium affects neither the lipid metabolism in isolated liver cells nor the secretion of acetoacetate from the cells, but that it completely inhibits the secretion of triglyceride.
