Effect of guanosine 3' : 5'-monophosphate on glucose oxidation and epinephrine-stimulated lipolysis in isolated rat epididymal fat cells.

The guanosine 3': 5'-monophosphate (cyclic GMP) level in isolated rat epididymal fat cells increased more than doubled 10 min after addition to the cells of carbamylcholine (10(-6) M) in the presence or absence of epinephrine (5 X 10(-7) M). Addition of carbamylcholine, cyclic GMP or dibutyryl cyclic GMP (10(-9) to 10(-5) M) did not affect glucose oxidation or epinephrine-stimulated lipolysis of the cells. No significant change in the cyclic GMP level was detected 2 min or 10 min after addition of insulin (1 mU/ml) to the cells, when glucose oxidation was stimulated and lipolysis induced by epinephrine was inhibited. These results indicate that the transient increase in the cyclic GMP level in the cells on treatment with carbamylcholine is not sufficient for expression of the effects of insulin.