Table 4

Adenylyl cyclase inhibition—IC₅₀ values for isobolographic analysis in GH₃MORDOR cells.

	IC₅₀ (95% Confidence Interval)
	Ligand Alone	Ligand in Combination	Theoretical IC₅₀	Interaction
		nM
DAMGO	671 (375–1199)	183 (127–263)	335 (279–402)	Synergistic^4-150
DPDPE	1.22 (0.872–1.70)	0.366 (0.254–0.525)	0.608 (0.506–0.731)
DAMGO	671 (375–1199)	181 (105–313)	335 (280–402)	Synergistic^4-150
TAN67	1.56 (1.14–2.13)	0.363 (0.210–0.627)	0.780 (0.652–0.934)

The ability of the μ-opioid agonist DAMGO (10 nM–30 μM) and the δ-opioid agonists DPDPE or TAN67 (0.02 nM–60 nM) administered alone or in equally effective concentrations to reduce intracellular cAMP levels was assessed in GH₃MORDOR cells. Refer toExperimental Procedures for a more complete description of this technique. The theoretical IC₅₀ values were derived from the line of additivity obtained from the isobolograph (Fig. 6). Data are presented as mean (95% confidence intervals) from five experiments performed in triplicate.

↵4-150 p < 0.05