Table 3.

Competition of various ligands for specific ¹²⁵I-Mel binding in NIH3T3 cells transfected with either rat MT1 or MT2 cDNA

Compound	K i		Ratio (MT2/MT1)
	MT1	MT2
I-Mel	6.22 ± 0.57 pM	4.81 ± 0.42 pM	0.77
Melatonin	290 ± 31 pM	378 ± 23 pM	1.31
6-Hydroxymelatonin	118 ± 68 nM	31.7 ± 4.9 nM	0.27
Luzindole	1.15 ± 0.19 μM	433 ± 138 nM	0.38
NAS	1.65 ± 0.42 μM	4.98 ± 2.84 μM	3.00

The K _i values are mean ± SEM of four experiments for each compound

I-Mel 2-iodomelatonin, NASN-acetyl-5-hydroxytryptamine