A patient with low blood sugar is administered glucagon. Predict the effect on pyruvate kinase activity in the liver.

• A. Glucagon will activate pyruvate kinase, increasing glycolysis.
• B. Glucagon will inhibit pyruvate kinase, increasing glycolysis.
• C. Glucagon will have no effect on pyruvate kinase activity.
• D. Glucagon will inhibit pyruvate kinase, reducing glycolysis.

Answer: (D)