McArdle Disease (glycogen storage disease 5) is caused bymutations in the phosphorylase enzyme in muscle. The symptoms aremuscle cramps, pain, and fatigue during strenuous exercise. A) Anischemic exercise test is often used as part of the diagnosticprocess. This test measures lactate in the blood but is not alwaysspecific for McArdle. Explain why lactate might be a gooddiagnostic measurement for this disease and how its production isregulated in muscle in a normal person versus a McArdle patient. B)A patient is undergoing an ischemic exercise test and is fed 13Cglucose prior to the test and then blood is drawn after the test.Explain how the following substrates would be labeled 1)alpha-ketoglutarate, 2) glucose 3) ribose, and 4) alanine. C) inpatients with McArdle would you expect electron chain activity toincrease, decrease, or remain the same in the muscle cell if theperson is at rest? exercising?
