Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1995 Apr 1;484(Pt 1):15–24. doi: 10.1113/jphysiol.1995.sp020644

Calcium-activated potassium channels in human platelets.

M P Mahaut-Smith 1
PMCID: PMC1157918  PMID: 7602515

Abstract

1. The effect of intracellular [Ca2+] ([Ca2+]i) on human platelet ion channels was studied using the nystatin whole-cell patch clamp recording technique. 2. Ionomycin-induced increases in [Ca2+]i rapidly activated a voltage-independent K(+)-selective channel with a slope conductance of 30 pS in 154 mM K+ saline. The single-channel conductance decreased in proportion to the square root of the external K+ concentration such that the estimated conductance in 5 mM K+ was approximately 5 pS. 3. The peak current under conditions expected to increase [Ca2+]i to micromolar levels indicated that each platelet possesses a small number (5-7) of 30 pS Ca(2+)-dependent K+ channels (KCa channels). 4. Spontaneous [Ca2+]i spiking was observed in many patch-clamped platelets using fura-2 fluorescence measurements. Each Ca2+ spike triggered up to five KCa channels at any one time. KCa channels were not active at resting levels of [Ca2+]i. 5. The results suggest that platelet KCa channels are not active under resting conditions but may have an important role in determining the membrane potential during Ca2+ signalling.

Full text

PDF
19

Selected References

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

  1. Bregestovski P., Redkozubov A., Alexeev A. Elevation of intracellular calcium reduces voltage-dependent potassium conductance in human T cells. 1986 Feb 27-Mar 5Nature. 319(6056):776–778. doi: 10.1038/319776a0. [DOI] [PubMed] [Google Scholar]
  2. Cook N. S. The pharmacology of potassium channels and their therapeutic potential. Trends Pharmacol Sci. 1988 Jan;9(1):21–28. doi: 10.1016/0165-6147(88)90238-6. [DOI] [PubMed] [Google Scholar]
  3. Davies T. A., Drotts D. L., Weil G. J., Simons E. R. Cytoplasmic Ca2+ is necessary for thrombin-induced platelet activation. J Biol Chem. 1989 Nov 25;264(33):19600–19606. [PubMed] [Google Scholar]
  4. Fine B. P., Hansen K. A., Salcedo J. R., Aviv A. Calcium-activated potassium channels in human platelets. Proc Soc Exp Biol Med. 1989 Nov;192(2):109–113. doi: 10.3181/00379727-192-42963. [DOI] [PubMed] [Google Scholar]
  5. Fukushima Y. Blocking kinetics of the anomalous potassium rectifier of tunicate egg studied by single channel recording. J Physiol. 1982 Oct;331:311–331. doi: 10.1113/jphysiol.1982.sp014374. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Gallin E. K. Evidence for a Ca-activated inwardly rectifying K channel in human macrophages. Am J Physiol. 1989 Jul;257(1 Pt 1):C77–C85. doi: 10.1152/ajpcell.1989.257.1.C77. [DOI] [PubMed] [Google Scholar]
  7. Grissmer S., Lewis R. S., Cahalan M. D. Ca(2+)-activated K+ channels in human leukemic T cells. J Gen Physiol. 1992 Jan;99(1):63–84. doi: 10.1085/jgp.99.1.63. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Grissmer S., Nguyen A. N., Cahalan M. D. Calcium-activated potassium channels in resting and activated human T lymphocytes. Expression levels, calcium dependence, ion selectivity, and pharmacology. J Gen Physiol. 1993 Oct;102(4):601–630. doi: 10.1085/jgp.102.4.601. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Grynkiewicz G., Poenie M., Tsien R. Y. A new generation of Ca2+ indicators with greatly improved fluorescence properties. J Biol Chem. 1985 Mar 25;260(6):3440–3450. [PubMed] [Google Scholar]
  10. Hagiwara S., Takahashi K. The anomalous rectification and cation selectivity of the membrane of a starfish egg cell. J Membr Biol. 1974;18(1):61–80. doi: 10.1007/BF01870103. [DOI] [PubMed] [Google Scholar]
  11. Hallam T. J., Rink T. J. Responses to adenosine diphosphate in human platelets loaded with the fluorescent calcium indicator quin2. J Physiol. 1985 Nov;368:131–146. doi: 10.1113/jphysiol.1985.sp015850. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. 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]
  13. Heemskerk J. W., Hoyland J., Mason W. T., Sage S. O. Spiking in cytosolic calcium concentration in single fibrinogen-bound fura-2-loaded human platelets. Biochem J. 1992 Apr 15;283(Pt 2):379–383. doi: 10.1042/bj2830379. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Horn R., Marty A. Muscarinic activation of ionic currents measured by a new whole-cell recording method. J Gen Physiol. 1988 Aug;92(2):145–159. doi: 10.1085/jgp.92.2.145. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Horne W. C., Simons E. R. Probes of transmembrane potentials in platelets: changes in cyanine dye fluorescence in response to aggregation stimuli. Blood. 1978 Apr;51(4):741–749. [PubMed] [Google Scholar]
  16. Latorre R., Oberhauser A., Labarca P., Alvarez O. Varieties of calcium-activated potassium channels. Annu Rev Physiol. 1989;51:385–399. doi: 10.1146/annurev.ph.51.030189.002125. [DOI] [PubMed] [Google Scholar]
  17. Livne A., Grinstein S., Rothstein A. Volume-regulating behavior of human platelets. J Cell Physiol. 1987 Jun;131(3):354–363. doi: 10.1002/jcp.1041310307. [DOI] [PubMed] [Google Scholar]
  18. MacIntyre D. E., Rink T. J. The role of platelet membrane potential in the initiation of platelet aggregation. Thromb Haemost. 1982 Feb 26;47(1):22–26. [PubMed] [Google Scholar]
  19. Mahaut-Smith M. P. Chloride channels in human platelets: evidence for activation by internal calcium. J Membr Biol. 1990 Oct;118(1):69–75. doi: 10.1007/BF01872205. [DOI] [PubMed] [Google Scholar]
  20. Mahaut-Smith M. P., Mason M. J. Ca(2+)-activated K+ channels in rat thymic lymphocytes: activation by concanavalin A. J Physiol. 1991 Aug;439:513–528. doi: 10.1113/jphysiol.1991.sp018679. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Mahaut-Smith M. P., Rink T. J., Collins S. C., Sage S. O. Voltage-gated potassium channels and the control of membrane potential in human platelets. J Physiol. 1990 Sep;428:723–735. doi: 10.1113/jphysiol.1990.sp018237. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Mahaut-Smith M. P., Schlichter L. C. Ca2(+)-activated K+ channels in human B lymphocytes and rat thymocytes. J Physiol. 1989 Aug;415:69–83. doi: 10.1113/jphysiol.1989.sp017712. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Maruyama Y. A patch-clamp study of mammalian platelets and their voltage-gated potassium current. J Physiol. 1987 Oct;391:467–485. doi: 10.1113/jphysiol.1987.sp016750. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Nishio H., Ikegami Y., Segawa T. Fluorescence digital image analysis of serotonin-induced calcium oscillations in single blood platelets. Cell Calcium. 1991 Feb-Mar;12(2-3):177–184. doi: 10.1016/0143-4160(91)90019-b. [DOI] [PubMed] [Google Scholar]
  25. Partiseti M., Choquet D., Diu A., Korn H. Differential regulation of voltage- and calcium-activated potassium channels in human B lymphocytes. J Immunol. 1992 Jun 1;148(11):3361–3368. [PubMed] [Google Scholar]
  26. Pipili E. Platelet membrane potential: simultaneous measurement of diSC3(5) fluorescence and optical density. Thromb Haemost. 1985 Oct 30;54(3):645–649. [PubMed] [Google Scholar]
  27. Rink T. J., Sage S. O. Calcium signaling in human platelets. Annu Rev Physiol. 1990;52:431–449. doi: 10.1146/annurev.ph.52.030190.002243. [DOI] [PubMed] [Google Scholar]
  28. Sakmann B., Trube G. Conductance properties of single inwardly rectifying potassium channels in ventricular cells from guinea-pig heart. J Physiol. 1984 Feb;347:641–657. doi: 10.1113/jphysiol.1984.sp015088. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Sauvé R., Simoneau C., Monette R., Roy G. Single-channel analysis of the potassium permeability in HeLa cancer cells: evidence for a calcium-activated potassium channel of small unitary conductance. J Membr Biol. 1986;92(3):269–282. doi: 10.1007/BF01869395. [DOI] [PubMed] [Google Scholar]
  30. Shibasaki T. Conductance and kinetics of delayed rectifier potassium channels in nodal cells of the rabbit heart. J Physiol. 1987 Jun;387:227–250. doi: 10.1113/jphysiol.1987.sp016571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Siess W. Molecular mechanisms of platelet activation. Physiol Rev. 1989 Jan;69(1):58–178. doi: 10.1152/physrev.1989.69.1.58. [DOI] [PubMed] [Google Scholar]
  32. Vostal J. G., Jackson W. L., Shulman N. R. Cytosolic and stored calcium antagonistically control tyrosine phosphorylation of specific platelet proteins. J Biol Chem. 1991 Sep 5;266(25):16911–16916. [PubMed] [Google Scholar]

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

RESOURCES