Endogenous carbon monoxide production after bicycle exercise in healthy subjects and in patients with hereditary spherocytosis.

The occurrence of haemolysis after bicycle exercise was studied by determination of, inter alia, the endogenous carbon monoxide production (VCO) before and after 20 min of exercise at a load of about 70% of predicted maximal oxygen uptake. Eight healthy subjects and six patients with hereditary spherocytosis were studied. VCO was 14.4 and 10.5 mumol CO x mmol per total body haeme per day before and after exercise, respectively, in healthy subjects, and 32.6 and 25.4 mumol CO x mmol per total body haeme per day in the patients. The differences were not statistically signficant. No significant changes occurred in serum total bilirubin, lactate dehydrogenase, haptoglobin or serum iron/total iron binding capacity. In conclusion, no increase in the destruction rate of red cells was observed after this type of exercise, neither in healthy subjects nor in patients with hereditary spherocytosis. In addition, a decrease in COHb of about 20% during exercise was observed in both groups. This could be explained by a redistribution of CO from haemoglobin to myoglobin in association with changes in intracellular oxygen tension in working muscles.