Effects of the ventilatory stimulant, doxapram on human TASK-3 (KCNK9, K2P9.1) channels and TASK-1 (KCNK3, K2P3.1) channels.

Autor: Cunningham KP; Medway School of Pharmacy, University of Greenwich and University of Kent, Chatham Maritime, UK., MacIntyre DE; Department of Drug Discovery, Galleon Pharmaceuticals, Inc, Horsham, Pennsylvania., Mathie A; Medway School of Pharmacy, University of Greenwich and University of Kent, Chatham Maritime, UK., Veale EL; Medway School of Pharmacy, University of Greenwich and University of Kent, Chatham Maritime, UK.
Jazyk: angličtina
Zdroj: Acta physiologica (Oxford, England) [Acta Physiol (Oxf)] 2020 Feb; Vol. 228 (2), pp. e13361. Date of Electronic Publication: 2019 Sep 18.
DOI: 10.1111/apha.13361
Abstrakt: Aims: The mode of action by which doxapram acts as a respiratory stimulant in humans is controversial. Studies in rodent models, have shown that doxapram is a more potent and selective inhibitor of TASK-1 and TASK-1/TASK-3 heterodimer channels, than TASK-3. Here we investigate the direct effect of doxapram and chirally separated, individual positive and negative enantiomers of the compound, on both human and mouse, homodimeric and heterodimeric variants of TASK-1 and TASK-3.
Methods: Whole-cell patch clamp electrophysiology on tsA201 cells was used to assess the potency of doxapram on cloned human or mouse TASK-1, TASK-3 and TASK-2 channels. Mutations of amino acids in the pore-lining region of TASK-3 channels were introduced using site-directed mutagenesis.
Results: Doxapram was an equipotent inhibitor of human TASK-1 and TASK-3 channels, compared with mouse channel variants, where it was more selective for TASK-1 and heterodimers of TASK-1 and TASK-3. The effect of doxapram could be attenuated by either the removal of the C-terminus of human TASK-3 channels or mutations of particular hydrophobic residues in the pore-lining region. These mutations, however, did not alter the effect of a known extracellular inhibitor of TASK-3, zinc. The positive enantiomer of doxapram, GAL-054, was a more potent antagonist of TASK channels, than doxapram, whereas the negative enantiomer, GAL-053, had little inhibitory effect.
Conclusion: These data show that in contrast to rodent channels, doxapram is a potent inhibitor of both TASK-1 and TASK-3 human channels, providing further understanding of the pharmacological profile of doxapram in humans and informing the development of new therapeutic agents.
(© 2019 The Authors. Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.)
Databáze: MEDLINE
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