期刊
BRITISH JOURNAL OF PHARMACOLOGY
卷 144, 期 1, 页码 59-70出版社
WILEY
DOI: 10.1038/sj.bjp.0706020
关键词
isoflurane; enflurane; barbiturates; propofol; etomidate; nitrous oxide; ethanol
资金
- NATIONAL INSTITUTE OF NEUROLOGICAL DISORDERS AND STROKE [R01NS038691] Funding Source: NIH RePORTER
- NIDA NIH HHS [K08 DA000428, DA 00428] Funding Source: Medline
- NINDS NIH HHS [NS 38691, R01 NS038691] Funding Source: Medline
1 Reticular thalamocortical neurons express a slowly inactivating T-type Ca2+ current that is quite similar to that recorded from recombinant Ca(v)3.3b (alphalIb) channels. These neurons also express abundant Ca(v)3.3 mRNA, suggesting that it underlies the native current. 2 Here, we test this hypothesis by comparing the anesthetic sensitivities of recombinant Ca(v)3.3b channels stably expressed in HEK 293 cells to native T channels in reticular thalamic neurons (nRT) from brain slices of young rats. 3 Barbiturates completely blocked both Ca(v)3.3 and nRT currents, with pentobarbital being about twice more potent in blocking Ca(v)3.3 currents. Isoflurane had about the same potency in blocking Ca(v)3.3 and nRT currents, but enflurane, etomidate, propofol, and ethanol exhibited 2-4 fold higher potency in blocking nRT vs Ca(v)3.3 currents. 4 Nitrous oxide (N2O; laughing gas) blocked completely nRT currents with IC50 of 20%, but did not significantly affect Ca(v)3.3 currents at four-fold higher concentrations. In addition, we observed that in lower concentration, N2O reversibly increased nRT but not Ca(v)3.3 currents. 5 In conclusion, contrasting anesthetic sensitivities of Ca(v)3.3 and nRT T-type Ca2+ channels strongly suggest that different molecular structures of Ca2+ channels give rise to slowly inactivating T-type Ca2+ currents. Furthermore, effects of volatile anesthetics and ethanol on slowly inactivating T-type Ca2+ channel variants may contribute to the clinical effects of these agents.
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