“Our results in the model tissues examined show (1) that alpha 2 agonist(s) depressed the secretion of NA and ATP caused by nerve … alpha 2-adrenoceptor-mediated autoinhibition for maintaining a low release probability in sympathetic nerve varicosities, and (5) that the alpha 2-adrenoceptor agonist, clonidine, …, Cd2+, ….”