Abstract
The high-pass filtering of small signals by the rod photoreceptor network was studied by intracellular recording in the isolated, perfused retina of the toad, Bufo marinus. Data were analyzed and interpreted in terms of the network analysis described in the preceding paper. External concentrations of Cs+ as high as 10 mM, which blocked the relaxation from peak to plateau of the rod's response to bright light, did not affect the filtering of small signals. The effects of reducing [Na+]o were not consistent with a direct action upon the mechanism underlying this filtering property. By contrast, raising external [K+] from 2.6 to 10 mM, which caused a fourfold reduction in EK, abolished the high-pass filtering of small signals. Analysis of the effects of external [K+] changes indicates that the underlying mechanism involves a K+ conductance that decreases with a delay when the rod is hyperpolarized. This conductance is not blocked by externally applied tetraethylammonium. Other experiments did not rule out the possibility that it might be activated by Ca++.
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Selected References
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- ARMSTRONG C. M., BINSTOCK L. ANOMALOUS RECTIFICATION IN THE SQUID GIANT AXON INJECTED WITH TETRAETHYLAMMONIUM CHLORIDE. J Gen Physiol. 1965 May;48:859–872. doi: 10.1085/jgp.48.5.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Armstrong C. M., Hille B. The inner quaternary ammonium ion receptor in potassium channels of the node of Ranvier. J Gen Physiol. 1972 Apr;59(4):388–400. doi: 10.1085/jgp.59.4.388. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Armstrong C. M. Inactivation of the potassium conductance and related phenomena caused by quaternary ammonium ion injection in squid axons. J Gen Physiol. 1969 Nov;54(5):553–575. doi: 10.1085/jgp.54.5.553. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Armstrong C. M. Interaction of tetraethylammonium ion derivatives with the potassium channels of giant axons. J Gen Physiol. 1971 Oct;58(4):413–437. doi: 10.1085/jgp.58.4.413. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Armstrong C. M. Time course of TEA(+)-induced anomalous rectification in squid giant axons. J Gen Physiol. 1966 Nov;50(2):491–503. doi: 10.1085/jgp.50.2.491. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Attwell D., Wilson M. Behaviour of the rod network in the tiger salamander retina mediated by membrane properties of individual rods. J Physiol. 1980 Dec;309:287–315. doi: 10.1113/jphysiol.1980.sp013509. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Atwater I., Ribalet B., Rojas E. Mouse pancreatic beta-cells: tetraethylammonium blockage of the potassium permeability increase induced by depolarization. J Physiol. 1979 Mar;288:561–574. [PMC free article] [PubMed] [Google Scholar]
- Bader C. R., Bertrand D., Schwartz E. A. Voltage-activated and calcium-activated currents studied in solitary rod inner segments from the salamander retina. J Physiol. 1982 Oct;331:253–284. doi: 10.1113/jphysiol.1982.sp014372. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baker P. F. Transport and metabolism of calcium ions in nerve. Prog Biophys Mol Biol. 1972;24:177–223. doi: 10.1016/0079-6107(72)90007-7. [DOI] [PubMed] [Google Scholar]
- Baylor D. A., Lamb T. D., Yau K. W. Responses of retinal rods to single photons. J Physiol. 1979 Mar;288:613–634. [PMC free article] [PubMed] [Google Scholar]
- Beaty G. N., Stefani E. Calcium dependent electrical activity in twitch muscle fibres of the frog. Proc R Soc Lond B Biol Sci. 1976 Aug 27;194(1114):141–150. doi: 10.1098/rspb.1976.0070. [DOI] [PubMed] [Google Scholar]
- Brown J. E., Pinto L. H. Ionic mechanism for the photoreceptor potential of the retina of Bufo marinus. J Physiol. 1974 Feb;236(3):575–591. doi: 10.1113/jphysiol.1974.sp010453. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Capovilla M., Cervetto L., Torre V. Effects of changing external potassium and chloride concentrations on the photoresponses of Bufo bufo rods. J Physiol. 1980 Oct;307:529–551. doi: 10.1113/jphysiol.1980.sp013452. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ciani S., Krasne S., Hagiwara S. A model for the effects of potential and external K+ concentration on the Cs+ blocking of inward rectification. Biophys J. 1980 Apr;30(1):199–204. doi: 10.1016/S0006-3495(80)85089-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fain G. L., Gerschenfeld H. M., Quandt F. N. Calcium spikes in toad rods. J Physiol. 1980 Jun;303:495–513. doi: 10.1113/jphysiol.1980.sp013300. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fain G. L., Lisman J. E. Membrane conductances of photoreceptors. Prog Biophys Mol Biol. 1981;37(2):91–147. doi: 10.1016/0079-6107(82)90021-9. [DOI] [PubMed] [Google Scholar]
- Fain G. L., Quandt F. N., Bastian B. L., Gerschenfeld H. M. Contribution of a caesium-sensitive conductance increase to the rod photoresponse. Nature. 1978 Mar 30;272(5652):466–469. doi: 10.1038/272467a0. [DOI] [PubMed] [Google Scholar]
- Fain G. L., Quandt F. N., Gerschenfeld H. M. Calcium-dependent regenerative responses in rods. Nature. 1977 Oct 20;269(5630):707–710. doi: 10.1038/269707a0. [DOI] [PubMed] [Google Scholar]
- Hagiwara S. Ca spike. Adv Biophys. 1973;4:71–102. [PubMed] [Google Scholar]
- Hille B. The selective inhibition of delayed potassium currents in nerve by tetraethylammonium ion. J Gen Physiol. 1967 May;50(5):1287–1302. doi: 10.1085/jgp.50.5.1287. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kaneko A., Shimazaki H. Synaptic transmission from photoreceptors to bipolar and horizontal cells in the carp retina. Cold Spring Harb Symp Quant Biol. 1976;40:537–546. doi: 10.1101/sqb.1976.040.01.050. [DOI] [PubMed] [Google Scholar]
- Lamb T. D., McNaughton P. A., Yau K. W. Spatial spread of activation and background desensitization in toad rod outer segments. J Physiol. 1981;319:463–496. doi: 10.1113/jphysiol.1981.sp013921. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Meech R. W. Calcium-dependent potassium activation in nervous tissues. Annu Rev Biophys Bioeng. 1978;7:1–18. doi: 10.1146/annurev.bb.07.060178.000245. [DOI] [PubMed] [Google Scholar]
- Meech R. W., Standen N. B. Potassium activation in Helix aspersa neurones under voltage clamp: a component mediated by calcium influx. J Physiol. 1975 Jul;249(2):211–239. doi: 10.1113/jphysiol.1975.sp011012. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Meech R. W. The sensitivity of Helix aspersa neurones to injected calcium ions. J Physiol. 1974 Mar;237(2):259–277. doi: 10.1113/jphysiol.1974.sp010481. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Reuter H. Divalent cations as charge carriers in excitable membranes. Prog Biophys Mol Biol. 1973;26:1–43. doi: 10.1016/0079-6107(73)90016-3. [DOI] [PubMed] [Google Scholar]
- Thompson S. H. Three pharmacologically distinct potassium channels in molluscan neurones. J Physiol. 1977 Feb;265(2):465–488. doi: 10.1113/jphysiol.1977.sp011725. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Torre V., Owen W. G. High-pass filtering of small signals by the rod network in the retina of the toad, Bufo marinus. Biophys J. 1983 Mar;41(3):305–324. doi: 10.1016/S0006-3495(83)84443-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yau K. W., McNaughton P. A., Hodgkin A. L. Effect of ions on the light-sensitive current in retinal rods. Nature. 1981 Aug 6;292(5823):502–505. doi: 10.1038/292502a0. [DOI] [PubMed] [Google Scholar]