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 ameliorate the hypoxic-induced disturbances of the isolated atria and ventricular strips from fed and 24 h fasted rats. Adenosine 100-50 microM exerted negative inotropic and chronotropic effects on the aerobic atria whereas 10 microM was ineffective. During hypoxia the atria underwent a decline of the peak developed tension and pacemaker frequency. Adenosine 50 microM was detrimental for the performance of hypoxic atria whereas a 10 microM neither affected the fall of peak tension nor the post-hypoxic recovery. Adenosine 100 microM did not affect the peak developed tension of the aerobic ventricular strips. Under hypoxia the ventricular strips from fed and fasted rats exhibited a pronounced depression of their peak developed tension together with the development of a strong contracture and a partial recovery after reoxygenation, which attained a similar extent in both nutritional states. Lactate output during hypoxia was lower in the group of fasted rats. Adenosine 100 microM did not exhibit any effect on the ventricular functions and glycolytic activity in both experimental groups. Results suggests that adenosine has no beneficial effects on rat isolated atria and ventricular strips in hypoxic conditions