Lack of protective effects of adenosine on the hypoxic and reoxygenated atria and ventricular strips of the rat

The aim of the investigation was to assess whether adenosine would ameliora te the hypoxic-induced disturbances of the isolated atria and ventricular s trips from fed and 24 h fasted rats. Adenosine 100-50 mu M exerted negative inotropic and chronotropic effects on the aerobic atria whereas 10 mu M wa s ineffective. During hypoxia the atria underwent a decline of the peak dev eloped tension and pacemaker frequency. Adenosine 50 mu M was detrimental f or the performance of hypoxic atria whereas a 10 mu M neither affected the fall of peak tension nor the post-hypoxic recovery. Adenosine 100 mu M did not affect the peak developed tension of the aerobic ventricular strips. Un der hypoxia the ventricular strips from fed and fasted rats exhibited a pro nounced depression of their peak developed tension together with the develo pment of a strong contracture and a partial recovery after reoxygenation, w hich attained a similar extent in both nutritional states. Lactate output d uring hypoxia was lower in the group of fasted rats. Adenosine 100 mu M did not exhibit any effect on the ventricular functions and glycolytic activit y in both experimental groups. Results suggests that adenosine has no benef icial effects on rat isolated atria and ventricular strips in hypoxic condi tions.