Changes in myocardial and coronary sinus blood oxygen tension induced by asphyxia and reoxygenation

1. This study analyzes variations of oxygen tension induced by asphyxia in the myocardium (MpO2) and coronary sinus blood (CSpO2) of the anesthetized open-chest dog. Oxygen tension was measured polarographically and arterial blood pressure and coronary blood flow were recorded simultaneously. 2. Asphyxia increased arterial pressure and coronary blood flow but decreased both MpO2 and CSpO2. 3. During the reoxygenation phase, arterial pressure and coronary flow decreased gradually. Reoxygenation induced a rapid but transient increase in CSpO2 above control levels. In contrast, MpO2 returned gradually to the basal state. 4. The mechanism(s) involved in the differential effects of asphyxia followed by reoxygenation on MpO2 and CSpO2 remain to be elucidated.