Effects of phenformin and alpha-bromopalmitate on fatty acid and glucose oxidation in muscle.

Hemidiaphragms removed from fasted rats which were treated with the fatty acid oxidation inhibitor, alpha-bromopalmitate (125-250 mg/kg, i.p.) oxidized less glucose to CO2 than vehicle-treated rats. Hypoglycemia was noted and was preceded by reduction of muscle palmitate oxidation and by increased plasma free fatty acids (FFA). However, phenformin (100 mg/kg, i.p.) lowered plasma FFA and diaphragm oxidation of both palmitic acid and glucose, without altering glucose levels. These results fail to support the hypothesis that phenformin lowers blood glucose secondary to inhibiton of fatty acid oxidation.