Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1990 Mar;422:381–395. doi: 10.1113/jphysiol.1990.sp017990

Effect of lowered extracellular pH on Ca2(+)-dependent K+ currents in type I cells from the neonatal rat carotid body.

C Peers 1
PMCID: PMC1190138  PMID: 1693683

Abstract

1. The whole-cell configuration of the patch-clamp technique was used to record K+ currents from type I cells enzymatically dispersed from the neonatal rat carotid body. The current-voltage (I-V) relationship for the K+ currents showed a prominent, outward shoulder at test potentials of between +10 and +30 mV. 2. The shoulder of the I-V curve could be enhanced by raising extracellular Ca2+ concentration or by bath application of 5 microM-Bay K 8644. It could also be suppressed by bath application of 100 microM-Cd2+ or 5 microM-methoxyverapamil (D600), indicating that a large component of the K+ current in these cells was activated by an influx of Ca2+ through its own channels during cell depolarization. 3. Potassium currents were also reversibly suppressed by 8 nM-charybdotoxin but unaffected by 100 nM-apamin, suggesting that the Ca2(+)-dependent K+ current was carried through large or intermediate conductance Ca2(+)-activated K+ channels. 4. Lowering the pH of the bathing medium from 7.40 to 7.00 reversibly reduced the K+ current amplitudes, and suppressed the shoulder normally seen in the I-V relationship. This effect was enhanced in the presence of 5 microM-Bay K 8644 and abolished in the presence of 5 microM-D600. 5. It is concluded that the Ca2(+)-dependent K+ channels of type I carotid body cells are selectively suppressed by extracellular acidity. Possible mechanisms underlying this effect, and its role in excitation of the carotid body are discussed.

Full text

PDF
381

Selected References

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

  1. Biscoe T. J., Duchen M. R., Eisner D. A., O'Neill S. C., Valdeolmillos M. Measurements of intracellular Ca2+ in dissociated type I cells of the rabbit carotid body. J Physiol. 1989 Sep;416:421–434. doi: 10.1113/jphysiol.1989.sp017769. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Biscoe T. J., Duchen M. R. Electrophysiological responses of dissociated type I cells of the rabbit carotid body to cyanide. J Physiol. 1989 Jun;413:447–468. doi: 10.1113/jphysiol.1989.sp017663. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Biscoe T. J., Purves M. J., Sampson S. R. The frequency of nerve impulses in single carotid body chemoreceptor afferent fibres recorded in vivo with intact circulation. J Physiol. 1970 May;208(1):121–131. doi: 10.1113/jphysiol.1970.sp009109. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. 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]
  5. Castle N. A., Haylett D. G., Jenkinson D. H. Toxins in the characterization of potassium channels. Trends Neurosci. 1989 Feb;12(2):59–65. doi: 10.1016/0166-2236(89)90137-9. [DOI] [PubMed] [Google Scholar]
  6. 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]
  7. Delpiano M. A., Hescheler J. Evidence for a PO2-sensitive K+ channel in the type-I cell of the rabbit carotid body. FEBS Lett. 1989 Jun 5;249(2):195–198. doi: 10.1016/0014-5793(89)80623-4. [DOI] [PubMed] [Google Scholar]
  8. Docherty R. J., Brown D. A. Interaction of 1,4-dihydropyridines with somatic Ca currents in hippocampal CA1 neurones of the guinea pig in vitro. Neurosci Lett. 1986 Sep 25;70(1):110–115. doi: 10.1016/0304-3940(86)90447-7. [DOI] [PubMed] [Google Scholar]
  9. Duchen M. R., Caddy K. W., Kirby G. C., Patterson D. L., Ponte J., Biscoe T. J. Biophysical studies of the cellular elements of the rabbit carotid body. Neuroscience. 1988 Jul;26(1):291–311. doi: 10.1016/0306-4522(88)90146-7. [DOI] [PubMed] [Google Scholar]
  10. Fox A. P., Nowycky M. C., Tsien R. W. Kinetic and pharmacological properties distinguishing three types of calcium currents in chick sensory neurones. J Physiol. 1987 Dec;394:149–172. doi: 10.1113/jphysiol.1987.sp016864. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. 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]
  12. Hescheler J., Delpiano M. A., Acker H., Pietruschka F. Ionic currents on type-I cells of the rabbit carotid body measured by voltage-clamp experiments and the effect of hypoxia. Brain Res. 1989 May 1;486(1):79–88. doi: 10.1016/0006-8993(89)91280-8. [DOI] [PubMed] [Google Scholar]
  13. Iijima T., Ciani S., Hagiwara S. Effects of the external pH on Ca channels: experimental studies and theoretical considerations using a two-site, two-ion model. Proc Natl Acad Sci U S A. 1986 Feb;83(3):654–658. doi: 10.1073/pnas.83.3.654. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Kass R. S., Tsien R. W. Multiple effects of calcium antagonists on plateau currents in cardiac Purkinje fibers. J Gen Physiol. 1975 Aug;66(2):169–192. doi: 10.1085/jgp.66.2.169. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. 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]
  16. López-Barneo J., López-López J. R., Ureña J., González C. Chemotransduction in the carotid body: K+ current modulated by PO2 in type I chemoreceptor cells. Science. 1988 Jul 29;241(4865):580–582. doi: 10.1126/science.2456613. [DOI] [PubMed] [Google Scholar]
  17. López-López J., González C., Ureña J., López-Barneo J. Low pO2 selectively inhibits K channel activity in chemoreceptor cells of the mammalian carotid body. J Gen Physiol. 1989 May;93(5):1001–1015. doi: 10.1085/jgp.93.5.1001. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Meech R. W., Standen N. B. Potassium activation in Helix aspersa neurones under voltage clamp: a component mediated by calcium influx. J Physiol. 1975 Jul;249(2):211–239. doi: 10.1113/jphysiol.1975.sp011012. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. 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]
  20. 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]

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

RESOURCES