Effects of exogenous adenosine on myocardial recovery after acute hemorrhage

: This study was designed to investigate whether reperfusion with adenosine had an effect on myocardial high energy phosphate levels and cardiac function in hearts extracted from acutely hemorrhaged rats. Rats were bled to a mean arterial pressure of 0 mmHg for 5, 10 or 15 minutes and hearts were removed and assigned to one of three groups: 1) Hearts freeze clamped for measuring high energy phosphates; 2) Hearts perfused by Langendorff method at a constant perfusion pressure of 90 mmHg for 30 minutes followed by freeze clamping and determining high energy phosphates and; 3) Hearts perfused with adenosine (20 microM) and treated in the same way as in group 2. In group 1 myocardial ATP was significantly reduced as compared with control. When reperfusion started within 10 min, ATP contents recovered to the levels of control, and there were no significant changes between groups 2 and 3. LVP and LV dp/dt in group 3 were significantly higher than those in group 2. When reperfusion started after 15 min, ATP remained at a low level and few hearts could be resuscitated. These findings suggest that early resuscitation with adenosine might facilitate cardiac recovery following acute hemorrhage.