computer analysis of competition of [ 3h ] cha binding by the stereoisomers of phenylisopropyl adenosine , r-pia ( ki = 5.3 nm ) and s-pia ( ki = 69 nm ) , as well as the 5'-substituted analogue , ethylcarboxamide adenosine ( neca ; ki = 4.2 nm ) suggest that [ 3h ] cha binding occurs to a single class of receptors of the ai subtype .
C0001443
adenosine
C0050789
neca