Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1991 Feb;433:663–676. doi: 10.1113/jphysiol.1991.sp018449

Potassium currents of isolated Necturus enterocytes: a whole-cell patch-clamp study.

D N Sheppard 1, M A Valverde 1, F Giraldez 1, F V Sepúlveda 1
PMCID: PMC1181394  PMID: 1841962

Abstract

1. The whole-cell recording mode of the patch-clamp technique was used to investigate the ionic currents of enterocytes isolated from the small intestine epithelium of Necturus maculosus. 2. When enterocytes were bathed in a physiological Ringer solution and dialysed with a K(+)-rich intracellular solution containing 1.5 x 10(-7) M intracellular Ca2+, strongly outwardly rectifying currents were observed. These currents were absent from enterocytes internally dialysed with K(+)-free solutions. 3. The kinetics of activation of the outwardly rectifying current was monoexponential with rate constants decreasing with depolarization from 160 ms at 20 mV to 40 ms at 60 mV. Similar voltage dependence of the relaxations after activation were observed. 4. Strongly buffering intracellular Ca2+ with EGTA inhibited outward currents, while increasing Ca2+ increased both their magnitude and rate of activation. 5. Bath application of the K+ channel inhibitors Ba2+ and TEA greatly attenuated outwardly rectifying currents. This observation plus the fact that tail currents reverse near EK points to K+ as the charge carrier in these currents. 6. Outside-out patches showed maxi K+ channels and lower conductance K+ channels. Averaging fluctuations of the maxi K+ channels gave a kinetic behaviour similar to the whole-cell currents.

Full text

PDF
664

Selected References

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

  1. 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]
  2. Bjerknes M., Cheng H. Methods for the isolation of intact epithelium from the mouse intestine. Anat Rec. 1981 Apr;199(4):565–574. doi: 10.1002/ar.1091990412. [DOI] [PubMed] [Google Scholar]
  3. Blum A. L., Shah G. T., Wiebelhaus V. D., Brennan F. T., Helander H. F., Ceballos R., Sachs G. Pronase method for isolation of viable cells from Necturus gastric mucosa. Gastroenterology. 1971 Aug;61(2):189–200. [PubMed] [Google Scholar]
  4. Cook D. L., Ikeuchi M., Fujimoto W. Y. Lowering of pHi inhibits Ca2+-activated K+ channels in pancreatic B-cells. Nature. 1984 Sep 20;311(5983):269–271. doi: 10.1038/311269a0. [DOI] [PubMed] [Google Scholar]
  5. Escande D., Thuringer D., Leguern S., Cavero I. The potassium channel opener cromakalim (BRL 34915) activates ATP-dependent K+ channels in isolated cardiac myocytes. Biochem Biophys Res Commun. 1988 Jul 29;154(2):620–625. doi: 10.1016/0006-291x(88)90184-2. [DOI] [PubMed] [Google Scholar]
  6. Fernandez J. M., Fox A. P., Krasne S. Membrane patches and whole-cell membranes: a comparison of electrical properties in rat clonal pituitary (GH3) cells. J Physiol. 1984 Nov;356:565–585. doi: 10.1113/jphysiol.1984.sp015483. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Findlay I., Dunne M. J., Petersen O. H. High-conductance K+ channel in pancreatic islet cells can be activated and inactivated by internal calcium. J Membr Biol. 1985;83(1-2):169–175. doi: 10.1007/BF01868748. [DOI] [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. Hume J. R., Leblanc N. Macroscopic K+ currents in single smooth muscle cells of the rabbit portal vein. J Physiol. 1989 Jun;413:49–73. doi: 10.1113/jphysiol.1989.sp017641. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Kunzelmann K., Pavenstädt H., Greger R. Characterization of potassium channels in respiratory cells. II. Inhibitors and regulation. Pflugers Arch. 1989 Jul;414(3):297–303. doi: 10.1007/BF00584630. [DOI] [PubMed] [Google Scholar]
  11. Latorre R., Miller C. Conduction and selectivity in potassium channels. J Membr Biol. 1983;71(1-2):11–30. doi: 10.1007/BF01870671. [DOI] [PubMed] [Google Scholar]
  12. Marty A., Neher E. Potassium channels in cultured bovine adrenal chromaffin cells. J Physiol. 1985 Oct;367:117–141. doi: 10.1113/jphysiol.1985.sp015817. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Pallotta B. S. Calcium-activated potassium channels in rat muscle inactivate from a short-duration open state. J Physiol. 1985 Jun;363:501–516. doi: 10.1113/jphysiol.1985.sp015724. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Sheppard D. N., Giraldez F., Sepúlveda F. V. K+ channels activated by L-alanine transport in isolated Necturus enterocytes. FEBS Lett. 1988 Jul 18;234(2):446–448. doi: 10.1016/0014-5793(88)80134-0. [DOI] [PubMed] [Google Scholar]
  15. Sheppard D. N., Giraldez F., Sepúlveda F. V. Kinetics of voltage- and Ca2+ activation and Ba2+ blockade of a large-conductance K+ channel from Necturus enterocytes. J Membr Biol. 1988 Oct;105(1):65–75. doi: 10.1007/BF01871107. [DOI] [PubMed] [Google Scholar]
  16. Tabares L., Ureña J., López-Barneo J. Properties of calcium and potassium currents of clonal adrenocortical cells. J Gen Physiol. 1989 Mar;93(3):495–519. doi: 10.1085/jgp.93.3.495. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Trautmann A., Marty A. Activation of Ca-dependent K channels by carbamoylcholine in rat lacrimal glands. Proc Natl Acad Sci U S A. 1984 Jan;81(2):611–615. doi: 10.1073/pnas.81.2.611. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Valverde M. A., Sheppard D. N., Giraldez F., Sepúlveda F. V. Two types of potassium currents seen in isolated Necturus enterocytes with the single-electrode voltage-clamp technique. J Physiol. 1991 Feb;433:645–661. doi: 10.1113/jphysiol.1991.sp018448. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Vergara C., Latorre R. Kinetics of Ca2+-activated K+ channels from rabbit muscle incorporated into planar bilayers. Evidence for a Ca2+ and Ba2+ blockade. J Gen Physiol. 1983 Oct;82(4):543–568. doi: 10.1085/jgp.82.4.543. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Yellen G. Single Ca2+-activated nonselective cation channels in neuroblastoma. Nature. 1982 Mar 25;296(5855):357–359. doi: 10.1038/296357a0. [DOI] [PubMed] [Google Scholar]

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

RESOURCES