Abstract
1. The permeability of AMPA (alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionate) receptors in the chick cochlear nucleus, the nucleus magnocellularis (nMAG), was examined by measuring the shift in reversal potential (Erev) of current through glutamate or neurotransmitter-gated channels in solutions of different ionic composition. 2. Outwardly rectifying glutamate-activated currents in outside-out membrane patches showed rapid activation and desensitization. The Erev of glutamate-evoked current in zero sodium solutions was dependent on the extracellular Ca2+ concentration. The relation between Erev and Ca2+ ionic activities could be described by the Goldman-Hodgkin-Katz equation with a permeability ratio, PCa/PCs, of 3.3. The PNa/PCs was estimated as 0.66, indicating a PCa/PNa of 5. 3. Evoked excitatory postsynaptic currents (EPSCs) could be recorded during local perfusion of the auditory nerve-nMAG synapse with isotonic Ca2+. The Erev of the EPSC shifted in the positive direction in high-Ca2+ solution as predicted from the preceding analysis. The fraction of current carried by Ca2+ during the AMPA receptor EPSC was estimated as 18%.
Full text
PDF






Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Burnashev N., Khodorova A., Jonas P., Helm P. J., Wisden W., Monyer H., Seeburg P. H., Sakmann B. Calcium-permeable AMPA-kainate receptors in fusiform cerebellar glial cells. Science. 1992 Jun 12;256(5063):1566–1570. doi: 10.1126/science.1317970. [DOI] [PubMed] [Google Scholar]
- Butler J. N. The thermodynamic activity of calcium ion in sodium chloride-calcium chloride electrolytes. Biophys J. 1968 Dec;8(12):1426–1433. doi: 10.1016/S0006-3495(68)86564-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dingledine R., Hume R. I., Heinemann S. F. Structural determinants of barium permeation and rectification in non-NMDA glutamate receptor channels. J Neurosci. 1992 Oct;12(10):4080–4087. doi: 10.1523/JNEUROSCI.12-10-04080.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gilbertson T. A., Scobey R., Wilson M. Permeation of calcium ions through non-NMDA glutamate channels in retinal bipolar cells. Science. 1991 Mar 29;251(5001):1613–1615. doi: 10.1126/science.1849316. [DOI] [PubMed] [Google Scholar]
- Gu Y. P., Huang L. Y. Block of kainate receptor channels by Ca2+ in isolated spinal trigeminal neurons of rat. Neuron. 1991 May;6(5):777–784. doi: 10.1016/0896-6273(91)90174-x. [DOI] [PubMed] [Google Scholar]
- Hollmann M., Heinemann S. Cloned glutamate receptors. Annu Rev Neurosci. 1994;17:31–108. doi: 10.1146/annurev.ne.17.030194.000335. [DOI] [PubMed] [Google Scholar]
- Iino M., Ozawa S., Tsuzuki K. Permeation of calcium through excitatory amino acid receptor channels in cultured rat hippocampal neurones. J Physiol. 1990 May;424:151–165. doi: 10.1113/jphysiol.1990.sp018060. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jahr C. E., Stevens C. F. Calcium permeability of the N-methyl-D-aspartate receptor channel in hippocampal neurons in culture. Proc Natl Acad Sci U S A. 1993 Dec 15;90(24):11573–11577. doi: 10.1073/pnas.90.24.11573. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jonas P., Racca C., Sakmann B., Seeburg P. H., Monyer H. Differences in Ca2+ permeability of AMPA-type glutamate receptor channels in neocortical neurons caused by differential GluR-B subunit expression. Neuron. 1994 Jun;12(6):1281–1289. doi: 10.1016/0896-6273(94)90444-8. [DOI] [PubMed] [Google Scholar]
- Mayer M. L., Westbrook G. L. Permeation and block of N-methyl-D-aspartic acid receptor channels by divalent cations in mouse cultured central neurones. J Physiol. 1987 Dec;394:501–527. doi: 10.1113/jphysiol.1987.sp016883. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Raman I. M., Zhang S., Trussell L. O. Pathway-specific variants of AMPA receptors and their contribution to neuronal signaling. J Neurosci. 1994 Aug;14(8):4998–5010. doi: 10.1523/JNEUROSCI.14-08-04998.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reyes A. D., Rubel E. W., Spain W. J. Membrane properties underlying the firing of neurons in the avian cochlear nucleus. J Neurosci. 1994 Sep;14(9):5352–5364. doi: 10.1523/JNEUROSCI.14-09-05352.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rogers J. H. Calretinin: a gene for a novel calcium-binding protein expressed principally in neurons. J Cell Biol. 1987 Sep;105(3):1343–1353. doi: 10.1083/jcb.105.3.1343. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rubel E. W., Hyson R. L., Durham D. Afferent regulation of neurons in the brain stem auditory system. J Neurobiol. 1990 Jan;21(1):169–196. doi: 10.1002/neu.480210112. [DOI] [PubMed] [Google Scholar]
- Warchol M. E., Dallos P. Neural coding in the chick cochlear nucleus. J Comp Physiol A. 1990 Mar;166(5):721–734. doi: 10.1007/BF00240021. [DOI] [PubMed] [Google Scholar]
- Zhang S., Trussell L. O. Voltage clamp analysis of excitatory synaptic transmission in the avian nucleus magnocellularis. J Physiol. 1994 Oct 1;480(Pt 1):123–136. doi: 10.1113/jphysiol.1994.sp020346. [DOI] [PMC free article] [PubMed] [Google Scholar]