ATP degradation products after ischemic exercise: hereditary lack of phosphorylase or carnitine palmityltransferase.

We measured purine degradation products of ATP in plasma after ischemic exercise in eight normal subjects, one patient with myophosphorylase deficiency (McArdle's disease), and one with carnitine palmityltransferase deficiency. Normal subjects increase hypoxanthine and inosine, but not xanthine. Plasma purine levels were elevated above the normal range after ischemic exercise in McArdle's disease and in carnitine palmityltransferase deficiency after fasting. Those changes implied abnormally accelerated ATP degradation in these two myopathies.