Fig. 5. Concentration of norepinephrine in perfusates of spinal cord slices from nerve-ligated animals with continuous perfusion with modified Krebs-bicarbonate solution (  circles ) or with the A1 and A2, nonselective adenosine agonist, 5′-  N -ethylcarboxamide adenosine (NECA). Values are mean ± SE of 8 to 12 experiments. *  P < 0.05 compared with 0 control.