Skip to main content
NCBI home page
Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1975 Jan;72(1):187–190. doi: 10.1073/pnas.72.1.187

Calcium role in depolarization-secretion coupling: an aequorin study in squid giant synapse.

R Llinás, C Nicholson
PMCID: PMC432267  PMID: 235124

Abstract

Aequorin, a protein that emits light in the presence of calcium, was injected in the presynaptic terminal of the squid giant synapse. This injection was preceded by intracellular tetraethylammonium administration, which prolonged the duration of the presynaptic action potential. After this procedure light emission was evoked by single presynaptic spikes capable of releasing synaptic transmitter. In a second set of experiments, presynaptic tetraethylammonium injection was followed by the administration of tetrodotoxin extracellularly, which abolished the presynaptic action potential. Under these conditions artificial depolarization of the presynaptic terminal triggered the release of synaptic transmitter, in a graded manner. However, as previously reported by other authors, membrane potential steps to an internal positive value of approximately plus 90 mV (the suppression potential) produced a blockage of transmitter release for the duration of the imposed potential. Synaptic transmission recurred, nevertheless, as the current injection was terminated. A similar set of experiments, performed after the intracellular injection of aequorin in the presynaptic fiber, demonstrated that the aequorin light response was evoked by membrane potential steps capable of releasing synaptic transmitter. If the membrane potential was made positive to the "suppression" level, no light response was evoked but the light emission appeared, as did transmitter release, at the end of the current pulse. These experiments demonstrate that release of transmitter is directly correlated with intracellular calcium concentration and that the suppression potential is compatible with the existence of a calcium equilibrium potential at the presynaptic terminal.

Full text

PDF
187

Selected References

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

  1. 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]
  2. Ashley C. C., Ridgway E. B. On the relationships between membrane potential, calcium transient and tension in single barnacle muscle fibres. J Physiol. 1970 Jul;209(1):105–130. doi: 10.1113/jphysiol.1970.sp009158. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. BRYANT S. H. Transmission in squid giant synapses: the importance of oxygen supply and the effects of drugs. J Gen Physiol. 1958 Jan 20;41(3):473–484. doi: 10.1085/jgp.41.3.473. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. BULLOCK T. H., HAGIWARA S. Intracellular recording from the giant synapse of the squid. J Gen Physiol. 1957 Mar 20;40(4):565–577. doi: 10.1085/jgp.40.4.565. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Baker P. F., Hodgkin A. L., Ridgway E. B. Depolarization and calcium entry in squid giant axons. J Physiol. 1971 Nov;218(3):709–755. doi: 10.1113/jphysiol.1971.sp009641. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Blaustein M. P. The interrelationship between sodium and calcium fluxes across cell membranes. Rev Physiol Biochem Pharmacol. 1974;70:33–82. doi: 10.1007/BFb0034293. [DOI] [PubMed] [Google Scholar]
  7. Blinks J. R. Calcium transients in striated muscle cells. Eur J Cardiol. 1973 Dec;1(2):135–142. [PubMed] [Google Scholar]
  8. Bloedel J., Gage P. W., Llinás R., Quastel D. M. Transmitter release at the squid giant synapse in the presence of tetrodotoxin. Nature. 1966 Oct 1;212(5057):49–50. doi: 10.1038/212049a0. [DOI] [PubMed] [Google Scholar]
  9. Ebashi S., Endo M., Otsuki I. Control of muscle contraction. Q Rev Biophys. 1969 Nov;2(4):351–384. doi: 10.1017/s0033583500001190. [DOI] [PubMed] [Google Scholar]
  10. HAGIWARA S., TASAKI I. A study on the mechanism of impulse transmission across the giant synapse of the squid. J Physiol. 1958 Aug 29;143(1):114–137. doi: 10.1113/jphysiol.1958.sp006048. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. HODGKIN A. L., KEYNES R. D. Movements of labelled calcium in squid giant axons. J Physiol. 1957 Sep 30;138(2):253–281. doi: 10.1113/jphysiol.1957.sp005850. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hastings J. W., Mitchell G., Mattingly P. H., Blinks J. R., Van Leeuwen M. Response of aequorin bioluminescence to rapid changes in calcium concentration. Nature. 1969 Jun 14;222(5198):1047–1050. doi: 10.1038/2221047a0. [DOI] [PubMed] [Google Scholar]
  13. Katz B., Miledi R. A study of synaptic transmission in the absence of nerve impulses. J Physiol. 1967 Sep;192(2):407–436. doi: 10.1113/jphysiol.1967.sp008307. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Katz B., Miledi R. Tetrodotoxin-resistant electric activity in presynaptic terminals. J Physiol. 1969 Aug;203(2):459–487. doi: 10.1113/jphysiol.1969.sp008875. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Kusano K., Livengood D. R., Werman R. Correlation of transmitter release with membrane properties of the presynaptic fiber of the squid giant synapse. J Gen Physiol. 1967 Dec;50(11):2579–2601. doi: 10.1085/jgp.50.11.2579. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Llinás R., Blinks J. R., Nicholson C. Calcium transient in presynaptic terminal of squid giant synapse: detection with aequorin. Science. 1972 Jun 9;176(4039):1127–1129. doi: 10.1126/science.176.4039.1127. [DOI] [PubMed] [Google Scholar]
  17. Meves H., Vogel W. Calcium inward currents in internally perfused giant axons. J Physiol. 1973 Nov;235(1):225–265. doi: 10.1113/jphysiol.1973.sp010386. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Miledi R., Slater C. R. The action of calcium on neuronal synapses in the squid. J Physiol. 1966 May;184(2):473–498. doi: 10.1113/jphysiol.1966.sp007927. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Miledi R. Transmitter release induced by injection of calcium ions into nerve terminals. Proc R Soc Lond B Biol Sci. 1973 Jul 3;183(1073):421–425. doi: 10.1098/rspb.1973.0026. [DOI] [PubMed] [Google Scholar]
  20. NARAHASHI T., MOORE J. W., SCOTT W. R. TETRODOTOXIN BLOCKAGE OF SODIUM CONDUCTANCE INCREASE IN LOBSTER GIANT AXONS. J Gen Physiol. 1964 May;47:965–974. doi: 10.1085/jgp.47.5.965. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Rüdel R., Taylor S. R. Aequorin luminescence during contraction of amphibian skeletal muscle. J Physiol. 1973 Aug;233(1):5P–6P. [PubMed] [Google Scholar]
  22. SHIMOMURA O., JOHNSON F. H., SAIGA Y. Extraction, purification and properties of aequorin, a bioluminescent protein from the luminous hydromedusan, Aequorea. J Cell Comp Physiol. 1962 Jun;59:223–239. doi: 10.1002/jcp.1030590302. [DOI] [PubMed] [Google Scholar]
  23. Stinnakre J., Tauc L. Mise en évidence d'une perméabilité postsynaptique au calcium chez l'aplysie. C R Acad Sci Hebd Seances Acad Sci D. 1974 Mar 4;278(10):1409–1412. [PubMed] [Google Scholar]
  24. TAKEUCHI A., TAKEUCHI N. Electrical changes in pre- and postsynaptic axons of the giant synapse of Loligo. J Gen Physiol. 1962 Jul;45:1181–1193. doi: 10.1085/jgp.45.6.1181. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences

RESOURCES