Adenosine protects against hypoxic injury at hypothermia in guinea pig papillary muscles

AbstractObjectives. To investigate the protective effects of adenosine against hypoxic injury at hypothermia; both magnitude and mechanisms. Design. Receptor versus non-receptor dependent mechanisms in cardioprotection by adenosine were examined in guinea pig papillary muscles exposed to glucose free hypoxia at 24°C. Contractile force amplitude (CFA) and action potential duration (APD) during increasing concentrations of adenosine at 37°C, 30°C and 24°C normoxia were also examined. Results. CFA was significantly improved after adenosine treatment during hypothermic hypoxia compared to control (80.7±17.4% vs 40.5±10.7%, p<0.001). Adenosine receptor antagonist SPT did not antagonize (64.6±21.1%), and adenosine receptor agonists (APNEA+NECA) could not mimic the cardioprotection (53.8±9.3%). MitoKCa blocker paxilline antagonized the cardioprotection (40.0±7.7%). During normoxic conditions hypothermia-induced increase in CFA was significantly decreased by adenosine (0.12–12 mM) whereas the increase in action p...