Local hypoxia does not elevate adenosine output from isolated gracilis muscle in anaesthetized dogs

1. The influence of local hypoxia on adenosine and lactate output from isolated perfused gracilis muscle was studied in anaesthetized dogs. 2. Oxygen tension in the arterial blood supplying the muscle was reduced by a membrane lung from 145.9 +/- 28.9 to 52.9 +/- 2.6 (moderate hypoxia) or 30.0 +/- 1.2 mmHg (severe hypoxia). 3. Moderate hypoxia did not significantly alter vascular resistance, but severe hypoxia reduced arterial perfusion pressure from 199.0 +/- 13.6 to 122.6 +/- 8.7 mmHg. 4. Veno-arterial (V-A) lactate was 0.47 +/- 0.13 mmol/L in normoxia; neither level of hypoxia changed it significantly. Veno-arterial adenosine was 74 +/- 78 nmol/L in normoxia. Moderate hypoxia decreased this to -36 +/- 59 nmol/L (P < 0.05), but the level of V-A adenosine in severe hypoxia (52 +/- 96 nmol/L) was similar to that in normoxia. 5. These data confirm that hypoxia does not directly stimulate adenosine output from oxidative skeletal muscle.