Effect of nifedipine on carbohydrate metabolism in the rat

The potential role of an oral administration of nifedipine was investigated in the rat. Therefore, animals were fed on a nifedipine-containing or control diet for 12 days. Nifedipine caused a significant decrease of liver glycogen (47.9 +/- 4.9 vs 132.6 +/- 17.1 micrograms/mg protein), whereas liver glucose (213.1 +/- 15.3 vs 110.4 +/- 6.4 micrograms/mg) and lactate (44.8 +/- 4.1 vs 26.5 +/- 1.8 nmol/mg) concentrations increased. Various concentrations of nifedipine failed to influence glycogenolysis but stimulated gluconeogenesis in isolated rat hepatocytes. Blood lactate and pyruvate levels were significantly elevated in the nifedipine pretreated rats, whereas ketone bodies remained constant. Nifedipine pretreatment also increased the rates of excretion of various electrolytes and water followed by significantly lower plasma sodium, potassium, phosphate, and normal glucose values. We conclude that nifedipine-induced liver glycogenolysis may deteriorate glucose tolerance in patients with an already impaired carbohydrate metabolism.