ATP, CP, and Lactate Concentrations in Muscle Tissue during Exercise in Male Patients with Tetralogy of Fallot

Abstract

Eight men, 19–33 years old, with tetralogy of Fallot (TOF) were examined by means of muscle biopsies at rest and during exercise, including maximal exercise. In four of them, Group II, who had had an intracardiac repair, the normal increase in blood and muscle lactate concentration with exercise was achieved. In the other four men, Group I, who were not totally corrected, low values for blood lactate concentrations at maximal exercise were found, averaging 4.7 mmol/l as compared to 11.6 mmol/l in Group II. Muscle lactate concentration, on the other hand, was higher for Group I, 17.9 mmol/kg w.w., than for Group II, 13.2 mmol/kg w.w. No difference in concentrations of ATP, CP, and glycogen was found between the groups at rest, and similar and normal decreases were obtained with exercise. No definite explanation can be given of the tissue-blood lactate gradient found in Group I. A possible cause may be an altered muscle blood flow, e.g. secondary to altered cardiac performance, high blood viscosity, and decreased muscular vascularization secondary to physical inactivity. It is concluded that the local accumulation of lactate in exercising muscle might limit exercise performance in Group I. The study also shows that blood lactate concentration cannot be used as a measure of the anaerobic metabolism in cyanotic patients with TOF.

Key Words:

• Aerobic and anaerobic work capacity
• ATP
• blood and muscle lactate
• blood gases
• CP
• glycogen
• oxygen deficit
• tetralogy of Fallot