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Chronic high inspired CO2 decreases excitability of mouse hippocampal neurons.

Chronic high inspired CO2 decreases excitability of mouse hippocampal neurons.

Authors :
Gu, Xiang Q.
Kanaan, Amjad
Hang Yao
Haddad, Gabriel G.
Source :
FASEB Journal; Apr2007, Vol. 21 Issue 6, pA925-A925, 1/5p
Publication Year :
2007

Abstract

To examine the effect of chronically elevated CO<subscript>2</subscript> on excitability and function of neurons, we exposed mice to 8% and 12% CO<subscript>2</subscript> for 4 weeks (starting at 2 days of age), and examined the properties of freshly dissociated hippocampal neurons obtained from slices. Chronic CO<subscript>2</subscript>-treated neurons (CC) had a similar input resistance (R<subscript>m</subscript>) and resting membrane potential (V<subscript>m</subscript>) as control (CON). While treatment with 8% CO<subscript>2</subscript> did not change the rheobase (64±11 pA, n=9 vs. 47±12 pA, n=8 for CC 8% vs. CON), 12% CO<subscript>2</subscript> treatment increased it significantly (73±8 pA, n=9, p=0.05). Furthermore, the 12% CO<subscript>2</subscript> but not the 8% CO<subscript>2</subscript> treatment decreased the Na<superscript>+</superscript> channel current density (244±36 pA/pF, n=17, vs. 436±56 pA/pF, n=18, for CC vs. CON, p=0.005). Recovery from inactivation was also lowered by 12% but not 8% CO<subscript>2</subscript>. Other gating properties of Na<superscript>+</superscript> current, such as voltage-conductance curve, steady state inactivation, and time constant for deactivation, were not modified by either treatment. Western blot analysis showed that the expression of Na<superscript>+</superscript> channel types I, II and III was not changed by 8% CO<subscript>2</subscript> treatment but their expression was significantly decreased by 20-30% (p=0.03) by the 12% treatment. We conclude from these data and others (Gu et al. 2004) that 1) neuronal excitability and Na<superscript>+</superscript> channel expression depend on the duration and level of CO<subscript>2</subscript> exposure and 2) maturational changes occur in early life regarding neuronal responsiveness to CO<subscript>2</subscript>. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
08926638
Volume :
21
Issue :
6
Database :
Complementary Index
Journal :
FASEB Journal
Publication Type :
Academic Journal
Accession number :
25597895
Full Text :
https://doi.org/10.1096/fasebj.21.6.a925