In Vitro Metabolism of Glucose in the Isolated Fat Cells of Rats Inoculated with a Growth Hormone Secreting Tumor (MtT-W15)

Abstract

Hypersomatotropism was induced in Wistar/Furth female rats by inoculation of MtT-W15 tumor. Parametrial fat was removed from pair-fed animals at different periods after the inoculation of the tumor. Isolated fat cells were incubated with U-¹⁴ C-glucose, and the conversion of ¹⁴C into CO₂ and lipids was measured. The changes in the metabolism of glucose in adipose tissue developed in three stages. In the very early stage of hypersomatotropism (serum growth hormone 7-9 ng/ml) there was an increased glucose utilization both in the absence and presence of insulin. One to two weeks later, when serum growth hormone had risen to clearly hypersomatotropic levels (36-116 ng/ml) there was a decreased baseline glucose utilization, which could still be corrected by the addition of insulin. When the animals had had the growth hormone producing tumor for several weeks, depot fats were depleted, and the conversion of glucose to CO₂ and lipids was decreased both in the absence and presence of insulin.

Key words

Hypersomatotropism - MtT-W15 Tumor - Glucose Utilization in Isolated Fat Cells - Lipogenesis - Insulin-Like Effect in Early Hypersomatotropism

1 Supported by grant MT-1202 from the Medical Research Council of Canada.

2 Presented in part at the Third Canadian Workshop on Diabetes, "Lipid Metabolism" on October 28, 1969 at Mont Gabriel, Quebec.

1 Supported by grant MT-1202 from the Medical Research Council of Canada.

2 Presented in part at the Third Canadian Workshop on Diabetes, "Lipid Metabolism" on October 28, 1969 at Mont Gabriel, Quebec.

3 Research Fellow, Medical Research Council of Canada. Present address: The Children's Hospital, University of Helsinki, 11 Stenbäck Street, Helsinki 29, Finland.