Altered purine and glycogen metabolism in skeletal muscle during exercise in patients with heart failure

Plasma levels of ammonia and hypoxanthine (HX) can be indices of purine nuc leotide degradation. The present study determined if patients with heart fa ilure (HF) have altered exercise plasma ammonia and HX levels relative to t he peak work rate performed. Blood lactate, plasma ammonia, and plasma HX l evels were measured in 59 patients with HF (New York Heart Association [NYH A] classes I:20, II:21, and III:18) and 21 controls at test and after a max imal cardiopulmonary exercise test. The peak work rate (normal and NYHA I, II, and III, 163 +/- 11, 152 +/- 9, 94 +/- 5, and 69 +/- 5 W) and peak oxyg en uptake ([VO2] 32.3 +/- 1.7, 25.1 +/- 0.9, 18.6 +/- 0.5, and 14.1 +/- 0.6 ml/min/kg) decreased as the NYHA functional class increased. The increment from rest to peak exercise (Delta) for lactate ([Delta lactate] 6.1 +/- 0. 3, 4.8 +/- 0.4, 4.6 +/- 0.3, and 2.9 +/- 0.3 mmol/L), Delta ammonia (132 +/ - 14, 119 +/- 20, 94 +/- 13, and 32 +/- 6 mu g/dL), and Delta HX (33.5 +/- 3.4 24.9 +/- 4.7, 20,6 +/- 3.0, and 9.9 +/- 1.2 mu mol/L) was progressively smaller as HF worsened. The ratio for Delta lactate to peak work rate (0.0 37 +/- 0.003, 0.032 +/- 0.004, 0.049 +/- 0.003, and 0.042 +/- 0.005) was hi gher in classes II to III HF, while the ratio for Delta ammonia to peak wor k rate (0.81 +/- 0.14, 0.78 +/- 0.16, 0.99 +/- 0.11, and 0.47 +/- 0.11) was significantly lower in class III HF. In summary, patients with HF exhibite d a smaller ammonia response with a higher lactate response to exercise whe n normalized with the peak work rate. These results suggest there may be an altered purine and glycogen metabolism during exercise in skeletal muscle in patients with HF. Copyright (C) 1999 by W.B. Saunders Company.