Several amino- and ammonio-substituted derivatives of adenosine were tested as effectors of adenosine receptors in different smooth muscle preparations and mouse neuroblastoma adenylate cyclase. The compounds did not affect adenosine receptors in smooth muscles. N6-[3-(trimethylammonio)propyl]adenosine was a weak stimulator of adenylate cyclase, and 3′-amino-3′-deoxyadenosine and 3′-rnonomethylamino-3′-deoxyadenosine antagonized the stimulation of adenylate cyclase by 2-chloroadenosine.