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Rationale: Nav1.1, 1.2, and 1.6 are transmembrane proteins acting as voltage-gated sodium channels implicated in various forms of epilepsy. There is a need for knowing their actual concentration in target tissues during drug development. Methods: Unique peptides for Nav1.1, Nav1.2, and Nav1.6 were selected as quantotropic peptides for each protein and used for their quantification in membranes from stably transfected HEK293 cells and rodent and human brain samples using ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry. Results: Nav 1.1, 1.2, and 1.6 protein expressions in three stably individually transfected HEK293 cell lines were found to be 2.1 ± 0.2, 6.4 ± 1.2, and 4.0 ± 0.6 fmol/µg membrane protein, respectively. In brains, Nav1.2 showed the highest expression, with approximately three times higher (P < 0.003) in rodents than in humans at 3.05 ± 0.57, with 3.35 ± 0.56 in mouse and rat brains and 1.09 ± 0.27 fmol/µg in human brain. Both Nav1.1 and 1.6 expressions were much lower in the brains, with approximately 40% less expression in human Nav1.1 than rodent Nav1.1 at 0.49 ± 0.1 (mouse), 0.43 ± 0.3 (rat), and 0.28 ± 0.04 (humans); whereas Nav1.6 had approximately 60% less expression in humans than rodents at 0.27 ± 0.09 (mouse), 0.26 ± 0.06 (rat), and 0.11 ± 0.02 (humans) fmol/µg membrane proteins. Conclusions: Multiple reaction monitoring was used to quantify sodium channels Nav1.1, 1.2, and 1.6 expressed in stably transfected HEK293 cells and brain tissues from mice, rats, and humans. We found significant differences in the expression of these channels in mouse, rat, and human brains. Nav expression ranking among the three species was Nav1.2 Nav1.1 > Nav1.6, with the human brain expressing much lower concentrations overall compared to rodent brain. [ABSTRACT FROM AUTHOR]

A range of complexes of Ce and Nd have been prepared to compare the chemistry of the non-reducible [(TpMe2)2LnX] (Ln=Ce, Nd) with that reported previously for the redox-active samarium ion. The chloride [(TpMe2)2NdCl] is a useful starting material for the preparation of the seven coordinate [Nd(TpMe2)2OAr] (Ar=C6H4-4-X; X=H, But, Br, Ph, OMe, F, Me) and [Nd(TpMe2)2NPh2]. Crystal structures of [Nd(TpMe2)2Cl] and [Nd(TpMe2)2NPh2] are isostructural with those of the analogous samarium species. The eight coordinate species [Nd(TpMe2)2(β-dike)] (β-dike=(RC&z.dbnd6;O)2CH, R=Me, Ph; But) and their cerium analogues (R=Ph, But) have also been prepared. The complexes are fluxional, the extent of this behaviour depending on the steric bulk of the substituents. The structure of [Nd(TpMe2)2(ButCO)2CH] has been determined. Finally, in efforts to prepare a neodymium hydride, the unexpected borohydride [Nd(TpMe2)2(H2BEt2)] has been isolated serendipitously and structurally characterized. [Copyright &y& Elsevier]

Rationale: Na v 1.1, 1.2, and 1.6 are transmembrane proteins acting as voltage-gated sodium channels implicated in various forms of epilepsy. There is a need for knowing their actual concentration in target tissues during drug development., Methods: Unique peptides for Na v 1.1, Na v 1.2, and Na v 1.6 were selected as quantotropic peptides for each protein and used for their quantification in membranes from stably transfected HEK293 cells and rodent and human brain samples using ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry., Results: Na v 1.1, 1.2, and 1.6 protein expressions in three stably individually transfected HEK293 cell lines were found to be 2.1 ± 0.2, 6.4 ± 1.2, and 4.0 ± 0.6 fmol/μg membrane protein, respectively. In brains, Na v 1.2 showed the highest expression, with approximately three times higher (P < 0.003) in rodents than in humans at 3.05 ± 0.57, with 3.35 ± 0.56 in mouse and rat brains and 1.09 ± 0.27 fmol/μg in human brain. Both Na v 1.1 and 1.6 expressions were much lower in the brains, with approximately 40% less expression in human Na v 1.1 than rodent Na v 1.1 at 0.49 ± 0.1 (mouse), 0.43 ± 0.3 (rat), and 0.28 ± 0.04 (humans); whereas Na v 1.6 had approximately 60% less expression in humans than rodents at 0.27 ± 0.09 (mouse), 0.26 ± 0.06 (rat), and 0.11 ± 0.02 (humans) fmol/μg membrane proteins., Conclusions: Multiple reaction monitoring was used to quantify sodium channels Na v 1.1, 1.2, and 1.6 expressed in stably transfected HEK293 cells and brain tissues from mice, rats, and humans. We found significant differences in the expression of these channels in mouse, rat, and human brains. Na v expression ranking among the three species was Na v 1.2 ≫ Na v 1.1 > Na v 1.6, with the human brain expressing much lower concentrations overall compared to rodent brain., (© 2023 John Wiley & Sons Ltd.)

There is confusion in the literature concerning the relative agonist efficacy of methadone at micro-opioid receptors (MOPrs). Here, we confirm that methadone is a full agonist in guanosine 5'-O-[gamma-thio]triphosphate (GTPgammaS) binding studies. Methadone, however, seems to have low efficacy in studies of MOPr activation of G-protein-gated potassium (GIRK) channels, but this is because it directly inhibits the GIRK channels. Methadone also inhibits alpha2-adrenoceptor-activated GIRK channels. Methadone is not a specific GIRK channel blocker. It also inhibits small conductance Ca2+-activated K+ (SK2) channels. We conclude that methadone is a full agonist at MOPrs that, as we and others have shown, induces MOPr desensitization and internalization.