Table 2.

The dose of each drug in milligrams per kilogram (95% CI in parentheses) that engendered 50% of injection-appropriate responding on the single-drug lever in each group

	0.1 pram vs. saline	1.0 sum vs. saline	0.1 pram vs. 1.0 sum or saline	1.0 sum vs. 0.1 pram or saline
Pramipexole	0.050 (0.011 to 0.22)	0.13 (0.041 to 0.43)	n.s.	0.18 (0.0072 to 23)
Sumanirole	0.56 (0.030 to 10)	0.53 (0.17 to 1.6)	n.s.	0.68 (0.20 to 2.2)
Quinpirole	n.s.	0.019 (0.0027 to 0.14)	Not tested	n.s.
7-OH-DPAT	n.s.	n.s.	Not tested	0.022 (0.0029 to 0.22)
Cocaine	n.s.	n.s.	Not tested	n.s.

ED50 values are only shown for drugs for which a linear regression indicated a significantly nonzero slope.

pram Pramipexole, sum sumanirole, n.s. not significant linear regression analysis.