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. 1973 Sep 1;62(3):239–254. doi: 10.1085/jgp.62.3.239

Light Response of a Giant Aplysia Neuron

Arthur M Brown 1, H Mack Brown 1
PMCID: PMC2226119  PMID: 4730667

Abstract

Illumination of an Aplysia giant neuron evokes a membrane hyperpolarization which is associated with a membrane conductance increase of 15%. The light response is best elicited at 490 nM: the neuron also has an absorption peak at this wavelength. At the resting potential (-50 to -60 mV) illumination evokes an outward current in a voltage-clamped cell. This current reverses sign very close to E K calculated from direct measurements of internal and external K+ activity. Increases in external K+ concentration shift the reversal potential of the light-evoked response by the same amount as the change in E K. Decreases in external Na+ or Cl- do not affect the response. Therefore, the response is attributed to an increase in K+ conductance. Pressure injection of Ca2+ into this neuron also hyperpolarizes the cell membrane. This effect is also due largely to an increase in K+ conductance. The light response after Ca2+ injection does not appear to be altered. Pressure injection of EGTA abolished or greatly reduced the light response. The effect was reversible. We suggest that light acts upon a single pigment in this neuron, releasing Ca2+ which in turn increases K+ conductance, thereby hyperpolarizing the neuronal membrane.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bortoff A., Norton A. L. An electrical model of the vertebrate photoreceptor cell. Vision Res. 1967 Mar;7(3):253–263. doi: 10.1016/0042-6989(67)90089-2. [DOI] [PubMed] [Google Scholar]
  2. Brown A. M., Berman P. R. Mechanism of excitation of Aplysia neurons by carbon dioxide. J Gen Physiol. 1970 Nov;56(5):543–558. doi: 10.1085/jgp.56.5.543. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Brown H. M., Brown A. M. Ionic basis of the photoresponse of Aplysia giant neuron: K + permeability increase. Science. 1972 Nov 17;178(4062):755–756. doi: 10.1126/science.178.4062.755. [DOI] [PubMed] [Google Scholar]
  4. Brown H. M., Hagiwara S., Koike H., Meech R. M. Membrane properties of a barnacle photoreceptor examined by the voltage clamp technique. J Physiol. 1970 Jun;208(2):385–413. doi: 10.1113/jphysiol.1970.sp009127. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Gorman A. L., McReynolds J. S., Barnes S. N. Photoreceptors in primitive chordates: fine structure, hyperpolarizing receptor potentials, and evolution. Science. 1971 Jun 4;172(3987):1052–1054. doi: 10.1126/science.172.3987.1052. [DOI] [PubMed] [Google Scholar]
  6. HINKE J. A. Glass micro-electrodes for measuring intracellular activities of sodium and potassium. Nature. 1959 Oct 17;184(Suppl 16):1257–1258. doi: 10.1038/1841257a0. [DOI] [PubMed] [Google Scholar]
  7. Jacklet J. W. Electrophysiological organization of the eye of Aplysia. J Gen Physiol. 1969 Jan;53(1):21–42. doi: 10.1085/jgp.53.1.21. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. KIKUCHI R., NAITO K., TANAKA I. Effect of sodium and potassium ions on the electrical activity of single cells in the lateral eye of the horseshoe crab. J Physiol. 1962 May;161:319–343. doi: 10.1113/jphysiol.1962.sp006889. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. McReynolds J. S., Gorman A. L. Membrane conductances and spectral sensitivities of Pecten photoreceptors. J Gen Physiol. 1970 Sep;56(3):392–406. doi: 10.1085/jgp.56.3.392. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Meech R. W. Intracellular calcium injection causes increased potassium conductance in Aplysia nerve cells. Comp Biochem Physiol A Comp Physiol. 1972 Jun 1;42(2):493–499. doi: 10.1016/0300-9629(72)90128-4. [DOI] [PubMed] [Google Scholar]
  11. Millecchia R., Mauro A. The ventral photoreceptor cells of Limulus. 3. A voltage-clamp study. J Gen Physiol. 1969 Sep;54(3):331–351. doi: 10.1085/jgp.54.3.331. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Russell J. M., Brown A. M. Active transport of chloride by the giant neuron of the Aplysia abdominal ganglion. J Gen Physiol. 1972 Nov;60(5):499–518. doi: 10.1085/jgp.60.5.499. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Russell J. M., Brown A. M. Active transport of potassium by the giant neuron of the aplysia abdominal ganglion. J Gen Physiol. 1972 Nov;60(5):519–533. doi: 10.1085/jgp.60.5.519. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Smith T. G., Stell W. K., Brown J. E., Freeman J. A., Murray G. C. A role for the sodium pump in photoreception in Limulus. Science. 1968 Oct 25;162(3852):456–458. doi: 10.1126/science.162.3852.456. [DOI] [PubMed] [Google Scholar]
  15. Toyoda J., Nosaki H., Tomita T. Light-induced resistance changes in single photoreceptors of Necturus and Gekko. Vision Res. 1969 Apr;9(4):453–463. doi: 10.1016/0042-6989(69)90134-5. [DOI] [PubMed] [Google Scholar]

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