Fig. 5.

Effect of exercise training on the HR response to adenosine before and after complete ANS blockade. Adenosine elicited significant reductions in HR with increasing doses of adenosine both before and after combined ANS blockade (propranolol HCl, 1.0 mg/kg + atropine sulfate 50 μg/kg). However, exercise training did not alter the HR response to adenosine; that is, there were no differences between the exercise-trained and sedentary groups. These data suggest that the sinoatrial function was not altered by exercise.