Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1990 Jun;425:117–132. doi: 10.1113/jphysiol.1990.sp018095

Tetraethylammonium blockade of apamin-sensitive and insensitive Ca2(+)-activated K+ channels in a pituitary cell line.

D G Lang 1, A K Ritchie 1
PMCID: PMC1189840  PMID: 1698974

Abstract

1. The pharmacological sensitivities and physiological contributions of two types of Ca2(+)-activated K+ channels (BK and SK) in GH3 cells were examined by the outside-out, whole-cell and cell-attached modes of the patch-clamp technique. 2. BK channels (250-300 pS in symmetrical 150 mM-K+) in outside-out patches were blocked by external tetraethylammonium (TEA) and by 50 nM-charybdotoxin (CTX), but were not blocked by apamin. 3. SK channels (9-14 pS in symmetrical 150 mM-K+) in outside-out patches were blocked by external TEA and by apamin, but were not blocked by 50 nM-CTX. 4. The dissociation constant (Kd) for TEA block of SK channels (3.1 +/- 0.37 mM) was 12-fold greater than the Kd for the BK channels (260 +/- 21 microM). The TEA blockade of both channels was not strongly voltage dependent: for both channels the TEA binding site sensed less than 20% of the membrane electric field. 5. Application of blockers of the BK channels (1 mM-TEA and 50 nM-CTX) to whole cells under current clamp prolonged action potential duration; whereas application of apamin, a selective blocker of the SK channel, inhibited a slowly decaying after-hyperpolarization and had little effect on action potential duration. Apamin also increased the firing rate in 30% of the spontaneously pacing cells. 6. It is suggested that BK channels contribute to action potential repolarization: whereas SK channels contribute to the regulation of action potential firing rate.

Full text

PDF
117

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. Barrett J. N., Magleby K. L., Pallotta B. S. Properties of single calcium-activated potassium channels in cultured rat muscle. J Physiol. 1982 Oct;331:211–230. doi: 10.1113/jphysiol.1982.sp014370. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Benham C. D., Bolton T. B., Lang R. J., Takewaki T. The mechanism of action of Ba2+ and TEA on single Ca2+-activated K+ -channels in arterial and intestinal smooth muscle cell membranes. Pflugers Arch. 1985 Feb;403(2):120–127. doi: 10.1007/BF00584088. [DOI] [PubMed] [Google Scholar]
  4. Blatz A. L., Magleby K. L. Ion conductance and selectivity of single calcium-activated potassium channels in cultured rat muscle. J Gen Physiol. 1984 Jul;84(1):1–23. doi: 10.1085/jgp.84.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Blatz A. L., Magleby K. L. Single apamin-blocked Ca-activated K+ channels of small conductance in cultured rat skeletal muscle. Nature. 1986 Oct 23;323(6090):718–720. doi: 10.1038/323718a0. [DOI] [PubMed] [Google Scholar]
  6. Capiod T., Ogden D. C. The properties of calcium-activated potassium ion channels in guinea-pig isolated hepatocytes. J Physiol. 1989 Feb;409:285–295. doi: 10.1113/jphysiol.1989.sp017497. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Fabiato A., Fabiato F. Calculator programs for computing the composition of the solutions containing multiple metals and ligands used for experiments in skinned muscle cells. J Physiol (Paris) 1979;75(5):463–505. [PubMed] [Google Scholar]
  8. Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
  9. Hermann A., Erxleben C. Charybdotoxin selectively blocks small Ca-activated K channels in Aplysia neurons. J Gen Physiol. 1987 Jul;90(1):27–47. doi: 10.1085/jgp.90.1.27. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Iwatsuki N., Petersen O. H. Action of tetraethylammonium on calcium-activated potassium channels in pig pancreatic acinar cells studied by patch-clamp single-channel and whole-cell current recording. J Membr Biol. 1985;86(2):139–144. doi: 10.1007/BF01870780. [DOI] [PubMed] [Google Scholar]
  11. Kawai T., Watanabe M. Blockade of Ca-activated K conductance by apamin in rat sympathetic neurones. Br J Pharmacol. 1986 Jan;87(1):225–232. doi: 10.1111/j.1476-5381.1986.tb10175.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. 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]
  13. Lang D. G., Ritchie A. K. Large and small conductance calcium-activated potassium channels in the GH3 anterior pituitary cell line. Pflugers Arch. 1987 Dec;410(6):614–622. doi: 10.1007/BF00581321. [DOI] [PubMed] [Google Scholar]
  14. MacKinnon R., Miller C. Mechanism of charybdotoxin block of the high-conductance, Ca2+-activated K+ channel. J Gen Physiol. 1988 Mar;91(3):335–349. doi: 10.1085/jgp.91.3.335. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. MacKinnon R., Reinhart P. H., White M. M. Charybdotoxin block of Shaker K+ channels suggests that different types of K+ channels share common structural features. Neuron. 1988 Dec;1(10):997–1001. doi: 10.1016/0896-6273(88)90156-0. [DOI] [PubMed] [Google Scholar]
  16. Marty A., Tan Y. P., Trautmann A. Three types of calcium-dependent channel in rat lacrimal glands. J Physiol. 1984 Dec;357:293–325. doi: 10.1113/jphysiol.1984.sp015501. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Miller C., Moczydlowski E., Latorre R., Phillips M. Charybdotoxin, a protein inhibitor of single Ca2+-activated K+ channels from mammalian skeletal muscle. Nature. 1985 Jan 24;313(6000):316–318. doi: 10.1038/313316a0. [DOI] [PubMed] [Google Scholar]
  18. Pennefather P., Lancaster B., Adams P. R., Nicoll R. A. Two distinct Ca-dependent K currents in bullfrog sympathetic ganglion cells. Proc Natl Acad Sci U S A. 1985 May;82(9):3040–3044. doi: 10.1073/pnas.82.9.3040. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Reinhart P. H., Chung S., Levitan I. B. A family of calcium-dependent potassium channels from rat brain. Neuron. 1989 Jan;2(1):1031–1041. doi: 10.1016/0896-6273(89)90227-4. [DOI] [PubMed] [Google Scholar]
  20. Ritchie A. K. Thyrotropin-releasing hormone stimulates a calcium-activated potassium current in a rat anterior pituitary cell line. J Physiol. 1987 Apr;385:611–625. doi: 10.1113/jphysiol.1987.sp016510. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Ritchie A. K. Two distinct calcium-activated potassium currents in a rat anterior pituitary cell line. J Physiol. 1987 Apr;385:591–609. doi: 10.1113/jphysiol.1987.sp016509. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Romey G., Lazdunski M. The coexistence in rat muscle cells of two distinct classes of Ca2+-dependent K+ channels with different pharmacological properties and different physiological functions. Biochem Biophys Res Commun. 1984 Jan 30;118(2):669–674. doi: 10.1016/0006-291x(84)91355-x. [DOI] [PubMed] [Google Scholar]
  23. Sands S. B., Lewis R. S., Cahalan M. D. Charybdotoxin blocks voltage-gated K+ channels in human and murine T lymphocytes. J Gen Physiol. 1989 Jun;93(6):1061–1074. doi: 10.1085/jgp.93.6.1061. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Smart T. G. Single calcium-activated potassium channels recorded from cultured rat sympathetic neurones. J Physiol. 1987 Aug;389:337–360. doi: 10.1113/jphysiol.1987.sp016660. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Vergara C., Moczydlowski E., Latorre R. Conduction, Blockade and Gating in a Ca -activated K Channel Incorporated into Planar Lipid Bilayers. Biophys J. 1984 Jan;45(1):73–76. doi: 10.1016/S0006-3495(84)84114-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Wong B. S., Adler M. Tetraethylammonium blockade of calcium-activated potassium channels in clonal anterior pituitary cells. Pflugers Arch. 1986 Sep;407(3):279–284. doi: 10.1007/BF00585303. [DOI] [PubMed] [Google Scholar]
  27. Woodhull A. M. Ionic blockage of sodium channels in nerve. J Gen Physiol. 1973 Jun;61(6):687–708. doi: 10.1085/jgp.61.6.687. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Yellen G. Ionic permeation and blockade in Ca2+-activated K+ channels of bovine chromaffin cells. J Gen Physiol. 1984 Aug;84(2):157–186. doi: 10.1085/jgp.84.2.157. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES