TY - JOUR
T1 - Stereoselective interaction of ketamine with recombinant μ, κ, and δ opioid receptors expressed in Chinese hamster ovary cells
AU - Hirota, Kazuyoshi
AU - Okawa, Hirobumi
AU - Appadu, Balraj L.
AU - Grandy, David K.
AU - Devi, Lakshmi A.
AU - Lambert, David G.
PY - 1999/1
Y1 - 1999/1
N2 - Background: The authors examined the interaction of ketamine with recombinant μ, κ, and δ opioid receptors and recombinant orphan opioid receptors expressed in Chinese hamster ovary cells (CHO-μ, CHO-κ, CHO-δ, and CHOORL1, respectively). Methods: CHO-μ, CHO-κ, and CHO-δ membranes were incubated with the opioid receptor radioligand [3H]diprenorphine at room temperature. Ketamine (racemic, R(-) and S(+)) was included at concentrations covering the clinical range. CHOORL1 membranes were incubated with [125I]Tyr14nociceptin and racemic ketamine at room temperature. The effects of racemic ketamine and selective opioid receptor agonists (μ: [D-Ala2, MePhe4, Gly(ol)5] enkephalin (DAMGO); κ: spiradoline or δ: [D-pen2, D-pen5] enkephalin (DPDPE)) on forskolin-stimulated cyclic adenosine monophosphate formation also were examined. Data are mean ± SEM. Results: Racemic ketamine increased the radioligand equilibrium dissociation constant for [3H]diprenorphine from 85 ± 5 to 273 ± 11, 91 ± 6 to 154 ± 16, and 372 ± 15 to 855 ± 42 pM in CHO-μ, CHO-κ, and CHO-δ, respectively. The concentration of radioligand bound at saturation was unaffected. In CHO-μ and CHO-κ cells, racemic ketamine did not slow the rate of naloxone-induced [3H]diprenorphine dissociation. Ketamine and its isomers also displaced [3H]diprenorphine binding to μ, κ, and δ receptors in a dose-dependent manner, with pKi values for racemic ketamine of 4.38 ± 0.02, 4.55 ± 0.04, and 3.57 ± 0.02, respectively. S(+)-ketamine was two to three times more potent than R(-)-ketamine at μ and κ receptors. Racemic ketamine displaced [125I]Tyr14nociceptin with an estimated affinity constant of 0.5 mM. Racemic ketamine inhibited the formation of cyclic adenosine monophosphatc (naloxone insensitive) in a dose-dependent manner (concentration producing 50% inhibition ∼ 2 mM) in all cell lines, including untransfected CHO cells. Ketamine (100 μM) reversed DAMGO (μ) and spiradoline (κ) inhibition of formation of cyclic adenosine monophosphate. Conclusions: Ketamine interacts stereoselectively with recombinant μ and κ opioid receptors.
AB - Background: The authors examined the interaction of ketamine with recombinant μ, κ, and δ opioid receptors and recombinant orphan opioid receptors expressed in Chinese hamster ovary cells (CHO-μ, CHO-κ, CHO-δ, and CHOORL1, respectively). Methods: CHO-μ, CHO-κ, and CHO-δ membranes were incubated with the opioid receptor radioligand [3H]diprenorphine at room temperature. Ketamine (racemic, R(-) and S(+)) was included at concentrations covering the clinical range. CHOORL1 membranes were incubated with [125I]Tyr14nociceptin and racemic ketamine at room temperature. The effects of racemic ketamine and selective opioid receptor agonists (μ: [D-Ala2, MePhe4, Gly(ol)5] enkephalin (DAMGO); κ: spiradoline or δ: [D-pen2, D-pen5] enkephalin (DPDPE)) on forskolin-stimulated cyclic adenosine monophosphate formation also were examined. Data are mean ± SEM. Results: Racemic ketamine increased the radioligand equilibrium dissociation constant for [3H]diprenorphine from 85 ± 5 to 273 ± 11, 91 ± 6 to 154 ± 16, and 372 ± 15 to 855 ± 42 pM in CHO-μ, CHO-κ, and CHO-δ, respectively. The concentration of radioligand bound at saturation was unaffected. In CHO-μ and CHO-κ cells, racemic ketamine did not slow the rate of naloxone-induced [3H]diprenorphine dissociation. Ketamine and its isomers also displaced [3H]diprenorphine binding to μ, κ, and δ receptors in a dose-dependent manner, with pKi values for racemic ketamine of 4.38 ± 0.02, 4.55 ± 0.04, and 3.57 ± 0.02, respectively. S(+)-ketamine was two to three times more potent than R(-)-ketamine at μ and κ receptors. Racemic ketamine displaced [125I]Tyr14nociceptin with an estimated affinity constant of 0.5 mM. Racemic ketamine inhibited the formation of cyclic adenosine monophosphatc (naloxone insensitive) in a dose-dependent manner (concentration producing 50% inhibition ∼ 2 mM) in all cell lines, including untransfected CHO cells. Ketamine (100 μM) reversed DAMGO (μ) and spiradoline (κ) inhibition of formation of cyclic adenosine monophosphate. Conclusions: Ketamine interacts stereoselectively with recombinant μ and κ opioid receptors.
KW - Adenylyl cyclase
KW - Opioid receptor antagonist
KW - Radioligand binding
KW - Radioreceptor assay
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U2 - 10.1097/00000542-199901000-00023
DO - 10.1097/00000542-199901000-00023
M3 - Article
C2 - 9915326
AN - SCOPUS:0032607618
SN - 0003-3022
VL - 90
SP - 174
EP - 182
JO - Anesthesiology
JF - Anesthesiology
IS - 1
ER -