Developmental change in the electrophysiological and pharmacological properties of acid-sensing ion channels in CNS neurons.
Acid-sensing ion channels (ASICs) are proton-gated cation channels that play important roles in the CNS including synaptic plasticity and acidosis-mediated neuronal injury. ASIC1a and ASIC2a subunits are predominant in CNS neurons, where homomultimeric and heteromultimeric channel configurations co-exist. Since ASIC1a and ASIC2a have dramatic differences in pH sensitivity, Ca(2+) permeability and channel kinetics, any change in the level of individual subunits may have significant effects on the properties and functions of ASICs. Using patch-clamp recording, fluorescent Ca(2+) imaging and molecular biological techniques, we show dramatic developmental changes in the properties of ASICs in mouse cortical neurons. For example, the amplitude of ASIC currents increases whereas desensitization decreases with neuronal maturation. Decreased H(+) affinity and acid-evoked [Ca(2+)](i) but increased Zn(2+) potentiation were also recorded in mature neurons. RT-PCR revealed significant increases in the ratio of ASIC2/ASIC1 mRNA with neuronal maturation. Thus, contributions of ASIC1a and ASIC2a to overall ASIC-mediated responses undergo distinct developmental changes. These findings may help in understanding the precise role of ASICs in physiological and pathological conditions at different developmental stages.
Li
Minghua
M
Robert S. Dow Neurobiology Laboratories, Legacy Clinical Research Center, 1225 NE 2nd Ave, Portland, OR 97232, USA.
Kratzer
Eric
E
Inoue
Koichi
K
Simon
Roger P
RP
Xiong
Zhi-Gang
ZG
D062565:Acid Sensing Ion Channels; D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000502:physiology*; D004594:Electrophysiology; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015222:Sodium Channels / Q000502:physiology*
C568267:ASIC1 protein, mouse; C568265:ASIC2 protein, mouse; D062565:Acid Sensing Ion Channels; D009419:Nerve Tissue Proteins; D015222:Sodium Channels; D002118:Calcium