TABLE 1

Comparison of binding parameters for [³H][Dmt¹]DALDA

Saturation binding was carried with [³H][Dmt¹]DALDA using membranes prepared from CHO cells transfected with hMOR (CHO-K1/hMOR), SH-SY5Y cells, which natively expresses μ and δ receptors and brain and spinal cord tissues from rats (Sprague-Dawley) and mice (CD-1). Membranes were incubated with [³H][Dmt¹]DALDA (0.010-2.000 nM) for 60 min at 25°C. Nonspecific binding was assessed by including 0.1 μM unlabeled [Dmt¹]DALDA or 10 μM naloxone. K_d and B_max were determined by fitting the data to a one-site binding model using nonlinear regression. Data are presented as mean ± S.E.M.; n = number of independent determinations.