Skip to main content
PMC 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
. 1990 Jun;87(12):4538–4542. doi: 10.1073/pnas.87.12.4538

Funnel-web spider venom and a toxin fraction block calcium current expressed from rat brain mRNA in Xenopus oocytes.

J W Lin 1, B Rudy 1, R Llinás 1
PMCID: PMC54151  PMID: 2162047

Abstract

Injection of rat brain mRNA into Xenopus oocytes has been shown to induce a calcium current (ICa) that is insensitive to dihydropyridine and omega-conotoxin. We examined the effect of funnel-web spider venom on two aspects of this expressed ICa: (i) the calcium-activated chloride current [ICl(Ca)] and (ii) the currents carried by barium ions through calcium channels (IBa). In the presence of 1.8 mM extracellular calcium, ICl(Ca) tail current became detectable between -30 and -40 mV from a holding potential of -80 mV and reached a maximal amplitude between 0 and +10 mV. Total spider venom partially (83%) and reversibly blocked the calcium-activated chloride current without changing its voltage sensitivity. A chromatographic toxin fraction from the venom also blocked this current (64%). The venom had a minimal effect on INa and IK. Direct investigation of inward current mediated by calcium channels was carried out in high-barium solution. IBa had a higher threshold of activation (-30 to -20 mV) and reached its maximal amplitude at about +20 mV. Total venom or a partly purified chromatographic toxic fraction blocked IBa partially and reversibly without changing its current-voltage characteristics. Furthermore, the extent of the total venom block depended on the concentration of extracellular barium. Only 35% of the IBa was blocked in 60 mM Ba2+, whereas the block increased to 65% and 71%, respectively, for 40 and 20 mM Ba2+. On the basis of these results, we propose that the calcium channels expressed from rat brain mRNA in Xenopus oocytes is similar to the recently discovered P-type channels.

Full text

PDF
4538

Selected References

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

  1. Anderson C. S., MacKinnon R., Smith C., Miller C. Charybdotoxin block of single Ca2+-activated K+ channels. Effects of channel gating, voltage, and ionic strength. J Gen Physiol. 1988 Mar;91(3):317–333. doi: 10.1085/jgp.91.3.317. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Barish M. E. A transient calcium-dependent chloride current in the immature Xenopus oocyte. J Physiol. 1983 Sep;342:309–325. doi: 10.1113/jphysiol.1983.sp014852. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Dierks P., van Ooyen A., Mantei N., Weissmann C. DNA sequences preceding the rabbit beta-globin gene are required for formation in mouse L cells of beta-globin RNA with the correct 5' terminus. Proc Natl Acad Sci U S A. 1981 Mar;78(3):1411–1415. doi: 10.1073/pnas.78.3.1411. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Doerner D., Pitler T. A., Alger B. E. Protein kinase C activators block specific calcium and potassium current components in isolated hippocampal neurons. J Neurosci. 1988 Nov;8(11):4069–4078. doi: 10.1523/JNEUROSCI.08-11-04069.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Dumont J. N. Oogenesis in Xenopus laevis (Daudin). I. Stages of oocyte development in laboratory maintained animals. J Morphol. 1972 Feb;136(2):153–179. doi: 10.1002/jmor.1051360203. [DOI] [PubMed] [Google Scholar]
  6. Eberhard D. A., Holz R. W. Intracellular Ca2+ activates phospholipase C. Trends Neurosci. 1988 Dec;11(12):517–520. doi: 10.1016/0166-2236(88)90174-9. [DOI] [PubMed] [Google Scholar]
  7. Gundersen C. B., Umbach J. A., Swartz B. E. Barbiturates depress currents through human brain calcium channels studied in Xenopus oocytes. J Pharmacol Exp Ther. 1988 Dec;247(3):824–829. [PubMed] [Google Scholar]
  8. Hille B., Woodhull A. M., Shapiro B. I. Negative surface charge near sodium channels of nerve: divalent ions, monovalent ions, and pH. Philos Trans R Soc Lond B Biol Sci. 1975 Jun 10;270(908):301–318. doi: 10.1098/rstb.1975.0011. [DOI] [PubMed] [Google Scholar]
  9. Kaneko S., Nomura Y. Cyclic AMP facilitates slow-inactivating Ca2+ channel currents expressed by Xenopus oocyte after injection of rat brain mRNA. Neurosci Lett. 1987 Dec 16;83(1-2):123–127. doi: 10.1016/0304-3940(87)90227-8. [DOI] [PubMed] [Google Scholar]
  10. Lancaster B., Nicoll R. A. Properties of two calcium-activated hyperpolarizations in rat hippocampal neurones. J Physiol. 1987 Aug;389:187–203. doi: 10.1113/jphysiol.1987.sp016653. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Leonard J. P., Nargeot J., Snutch T. P., Davidson N., Lester H. A. Ca channels induced in Xenopus oocytes by rat brain mRNA. J Neurosci. 1987 Mar;7(3):875–881. doi: 10.1523/JNEUROSCI.07-03-00875.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Leung H. T., Branton W. D., Phillips H. S., Jan L., Byerly L. Spider toxins selectively block calcium currents in Drosophila. Neuron. 1989 Dec;3(6):767–772. doi: 10.1016/0896-6273(89)90245-6. [DOI] [PubMed] [Google Scholar]
  13. Llinás R. R. The intrinsic electrophysiological properties of mammalian neurons: insights into central nervous system function. Science. 1988 Dec 23;242(4886):1654–1664. doi: 10.1126/science.3059497. [DOI] [PubMed] [Google Scholar]
  14. Llinás R., Sugimori M. Electrophysiological properties of in vitro Purkinje cell somata in mammalian cerebellar slices. J Physiol. 1980 Aug;305:171–195. doi: 10.1113/jphysiol.1980.sp013357. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Llinás R., Sugimori M., Lin J. W., Cherksey B. Blocking and isolation of a calcium channel from neurons in mammals and cephalopods utilizing a toxin fraction (FTX) from funnel-web spider poison. Proc Natl Acad Sci U S A. 1989 Mar;86(5):1689–1693. doi: 10.1073/pnas.86.5.1689. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Llinás R., Yarom Y. Properties and distribution of ionic conductances generating electroresponsiveness of mammalian inferior olivary neurones in vitro. J Physiol. 1981 Jun;315:569–584. doi: 10.1113/jphysiol.1981.sp013764. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Miledi R. A calcium-dependent transient outward current in Xenopus laevis oocytes. Proc R Soc Lond B Biol Sci. 1982 Jul 22;215(1201):491–497. doi: 10.1098/rspb.1982.0056. [DOI] [PubMed] [Google Scholar]
  18. Miledi R., Parker I. Chloride current induced by injection of calcium into Xenopus oocytes. J Physiol. 1984 Dec;357:173–183. doi: 10.1113/jphysiol.1984.sp015495. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Nowycky M. C., Fox A. P., Tsien R. W. Three types of neuronal calcium channel with different calcium agonist sensitivity. Nature. 1985 Aug 1;316(6027):440–443. doi: 10.1038/316440a0. [DOI] [PubMed] [Google Scholar]
  20. Suszkiw J. B., Murawsky M. M., Shi M. Further characterization of phasic calcium influx in rat cerebrocortical synaptosomes: inferences regarding calcium channel type(s) in nerve endings. J Neurochem. 1989 Apr;52(4):1260–1269. doi: 10.1111/j.1471-4159.1989.tb01874.x. [DOI] [PubMed] [Google Scholar]
  21. Suszkiw J. B., O'Leary M. E., Murawsky M. M., Wang T. Presynaptic calcium channels in rat cortical synaptosomes: fast-kinetics of phasic calcium influx, channel inactivation, and relationship to nitrendipine receptors. J Neurosci. 1986 May;6(5):1349–1357. doi: 10.1523/JNEUROSCI.06-05-01349.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Woodward J. J., Rezazadeh S. M., Leslie S. W. Differential sensitivity of synaptosomal calcium entry and endogenous dopamine release to omega-conotoxin. Brain Res. 1988 Dec 13;475(1):141–145. doi: 10.1016/0006-8993(88)90207-7. [DOI] [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