Effects of O2 breathing on RQ, blood flow, and developed tension in in situ dog muscle.

The Vo2, VCO2, RQ, blood flow and developed tension of in situ dog gastrocnemius muscle were studied during contractions at 2.5 tw/sec for both normoxic and hyperoxic breathing conditions. Vo2 and developed tension were not significantly altered by the breathing gas changes. CaO2 rose by 11% during O2-breathing, however, a significant decrease of 15% in muscle blood flow resulted in no significant change in O2-transport (CaO2 X Q) to muscle comparing hyperoxia to normoxia. Hyperoxia resulted in a significant decrease in muscle VCO2 and RQ. The cause of the RQ change with breathing gas O2 content is not certain, however, evidence is presented indicating that infused epinephrine and propranolol can effect the response.