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. 1993 May 1;101(5):767–797. doi: 10.1085/jgp.101.5.767

Permeation and gating properties of the L-type calcium channel in mouse pancreatic beta cells

PMCID: PMC2216780  PMID: 7687645

Abstract

Ba2+ currents through L-type Ca2+ channels were recorded from cell- attached patches on mouse pancreatic beta cells. In 10 mM Ba2+, single- channel currents were recorded at -70 mV, the beta cell resting membrane potential. This suggests that Ca2+ influx at negative membrane potentials may contribute to the resting intracellular Ca2+ concentration and thus to basal insulin release. Increasing external Ba2+ increased the single-channel current amplitude and shifted the current-voltage relation to more positive potentials. This voltage shift could be modeled by assuming that divalent cations both screen and bind to surface charges located at the channel mouth. The single- channel conductance was related to the bulk Ba2+ concentration by a Langmuir isotherm with a dissociation constant (Kd(gamma)) of 5.5 mM and a maximum single-channel conductance (gamma max) of 22 pS. A closer fit to the data was obtained when the barium concentration at the membrane surface was used (Kd(gamma) = 200 mM and gamma max = 47 pS), which suggests that saturation of the concentration-conductance curve may be due to saturation of the surface Ba2+ concentration. Increasing external Ba2+ also shifted the voltage dependence of ensemble currents to positive potentials, consistent with Ba2+ screening and binding to membrane surface charge associated with gating. Ensemble currents recorded with 10 mM Ca2+ activated at more positive potentials than in 10 mM Ba2+, suggesting that external Ca2+ binds more tightly to membrane surface charge associated with gating. The perforated-patch technique was used to record whole-cell currents flowing through L-type Ca2+ channels. Inward currents in 10 mM Ba2+ had a similar voltage dependence to those recorded at a physiological Ca2+ concentration (2.6 mM). BAY-K 8644 (1 microM) increased the amplitude of the ensemble and whole-cell currents but did not alter their voltage dependence. Our results suggest that the high divalent cation solutions usually used to record single L-type Ca2+ channel activity produce a positive shift in the voltage dependence of activation (approximately 32 mV in 100 mM Ba2+).

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Selected References

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  1. Al-Mahmood H. A., el-Khatim M. S., Gumaa K. A., Thulesius O. The effect of calcium-blockers nicardipine, darodipine, PN-200-110 and nifedipine on insulin release from isolated rat pancreatic islets. Acta Physiol Scand. 1986 Feb;126(2):295–298. doi: 10.1111/j.1748-1716.1986.tb07817.x. [DOI] [PubMed] [Google Scholar]
  2. Almers W., McCleskey E. W. Non-selective conductance in calcium channels of frog muscle: calcium selectivity in a single-file pore. J Physiol. 1984 Aug;353:585–608. doi: 10.1113/jphysiol.1984.sp015352. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Armstrong C. M., Neyton J. Ion permeation through calcium channels. A one-site model. Ann N Y Acad Sci. 1991;635:18–25. doi: 10.1111/j.1749-6632.1991.tb36477.x. [DOI] [PubMed] [Google Scholar]
  4. Ashcroft F. M., Kelly R. P., Smith P. A. Two types of Ca channel in rat pancreatic beta-cells. Pflugers Arch. 1990 Jan;415(4):504–506. doi: 10.1007/BF00373633. [DOI] [PubMed] [Google Scholar]
  5. Ashcroft F. M., Stanfield P. R. Calcium and potassium currents in muscle fibres of an insect (Carausius morosus). J Physiol. 1982 Feb;323:93–115. doi: 10.1113/jphysiol.1982.sp014063. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Attwell D., Eisner D. Discrete membrane surface charge distributions. Effect of fluctuations near individual channels. Biophys J. 1978 Dec;24(3):869–875. doi: 10.1016/S0006-3495(78)85426-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Bokvist K., Rorsman P., Smith P. A. Block of ATP-regulated and Ca2(+)-activated K+ channels in mouse pancreatic beta-cells by external tetraethylammonium and quinine. J Physiol. 1990 Apr;423:327–342. doi: 10.1113/jphysiol.1990.sp018025. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Bokvist K., Rorsman P., Smith P. A. Effects of external tetraethylammonium ions and quinine on delayed rectifying K+ channels in mouse pancreatic beta-cells. J Physiol. 1990 Apr;423:311–325. doi: 10.1113/jphysiol.1990.sp018024. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Boschero A. C., Carroll P. B., De Souza C., Atwater I. Effects of Ca2+ channel agonist-antagonist enantiomers of dihydropyridine 202791 on insulin release, 45Ca uptake and electrical activity in isolated pancreatic islets. Exp Physiol. 1990 Jul;75(4):547–558. doi: 10.1113/expphysiol.1990.sp003431. [DOI] [PubMed] [Google Scholar]
  10. Byerly L., Chase P. B., Stimers J. R. Permeation and interaction of divalent cations in calcium channels of snail neurons. J Gen Physiol. 1985 Apr;85(4):491–518. doi: 10.1085/jgp.85.4.491. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Ceña V., Stutzin A., Rojas E. Effects of calcium and Bay K-8644 on calcium currents in adrenal medullary chromaffin cells. J Membr Biol. 1989 Dec;112(3):255–265. doi: 10.1007/BF01870956. [DOI] [PubMed] [Google Scholar]
  12. Coronado R., Affolter H. Insulation of the conduction pathway of muscle transverse tubule calcium channels from the surface charge of bilayer phospholipid. J Gen Physiol. 1986 Jun;87(6):933–953. doi: 10.1085/jgp.87.6.933. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Cota G., Stefani E. Saturation of calcium channels and surface charge effects in skeletal muscle fibres of the frog. J Physiol. 1984 Jun;351:135–154. doi: 10.1113/jphysiol.1984.sp015238. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. FRANKENHAEUSER B. Sodium permeability in toad nerve and in squid nerve. J Physiol. 1960 Jun;152:159–166. doi: 10.1113/jphysiol.1960.sp006477. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Fox A. P., Nowycky M. C., Tsien R. W. Single-channel recordings of three types of calcium channels in chick sensory neurones. J Physiol. 1987 Dec;394:173–200. doi: 10.1113/jphysiol.1987.sp016865. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Ganitkevich VYa, Isenberg G. Contribution of two types of calcium channels to membrane conductance of single myocytes from guinea-pig coronary artery. J Physiol. 1990 Jul;426:19–42. doi: 10.1113/jphysiol.1990.sp018125. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Ganitkevich VYa, Shuba M. F., Smirnov S. V. Saturation of calcium channels in single isolated smooth muscle cells of guinea-pig taenia caeci. J Physiol. 1988 May;399:419–436. doi: 10.1113/jphysiol.1988.sp017089. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. HODGKIN A. L., KATZ B. The effect of sodium ions on the electrical activity of giant axon of the squid. J Physiol. 1949 Mar 1;108(1):37–77. doi: 10.1113/jphysiol.1949.sp004310. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Hagiwara S., Takahashi K. Surface density of calcium ions and calcium spikes in the barnacle muscle fiber membrane. J Gen Physiol. 1967 Jan;50(3):583–601. doi: 10.1085/jgp.50.3.583. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Henquin J. C., Meissner H. P. Significance of ionic fluxes and changes in membrane potential for stimulus-secretion coupling in pancreatic B-cells. Experientia. 1984 Oct 15;40(10):1043–1052. doi: 10.1007/BF01971450. [DOI] [PubMed] [Google Scholar]
  21. Hess P., Lansman J. B., Tsien R. W. Calcium channel selectivity for divalent and monovalent cations. Voltage and concentration dependence of single channel current in ventricular heart cells. J Gen Physiol. 1986 Sep;88(3):293–319. doi: 10.1085/jgp.88.3.293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Hess P., Lansman J. B., Tsien R. W. Different modes of Ca channel gating behaviour favoured by dihydropyridine Ca agonists and antagonists. Nature. 1984 Oct 11;311(5986):538–544. doi: 10.1038/311538a0. [DOI] [PubMed] [Google Scholar]
  23. Hess P., Tsien R. W. Mechanism of ion permeation through calcium channels. 1984 May 31-Jun 6Nature. 309(5967):453–456. doi: 10.1038/309453a0. [DOI] [PubMed] [Google Scholar]
  24. 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]
  25. Kass R. S., Krafte D. S. Negative surface charge density near heart calcium channels. Relevance to block by dihydropyridines. J Gen Physiol. 1987 Apr;89(4):629–644. doi: 10.1085/jgp.89.4.629. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Korn S. J., Horn R. Influence of sodium-calcium exchange on calcium current rundown and the duration of calcium-dependent chloride currents in pituitary cells, studied with whole cell and perforated patch recording. J Gen Physiol. 1989 Nov;94(5):789–812. doi: 10.1085/jgp.94.5.789. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Malaisse-Lagae F., Mathias P. C., Malaisse W. J. Gating and blocking of calcium channels by dihydropyridines in the pancreatic B-cell. Biochem Biophys Res Commun. 1984 Sep 28;123(3):1062–1068. doi: 10.1016/s0006-291x(84)80241-7. [DOI] [PubMed] [Google Scholar]
  28. Malécot C. O., Feindt P., Trautwein W. Intracellular N-methyl-D-glucamine modifies the kinetics and voltage-dependence of the calcium current in guinea pig ventricular heart cells. Pflugers Arch. 1988 Mar;411(3):235–242. doi: 10.1007/BF00585109. [DOI] [PubMed] [Google Scholar]
  29. Markwardt F., Nilius B. Modulation of calcium channel currents in guinea-pig single ventricular heart cells by the dihydropyridine Bay K 8644. J Physiol. 1988 May;399:559–575. doi: 10.1113/jphysiol.1988.sp017096. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. McLaughlin S. G., Szabo G., Eisenman G. Divalent ions and the surface potential of charged phospholipid membranes. J Gen Physiol. 1971 Dec;58(6):667–687. doi: 10.1085/jgp.58.6.667. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Plant T. D. Properties and calcium-dependent inactivation of calcium currents in cultured mouse pancreatic B-cells. J Physiol. 1988 Oct;404:731–747. doi: 10.1113/jphysiol.1988.sp017316. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Prentki M., Matschinsky F. M. Ca2+, cAMP, and phospholipid-derived messengers in coupling mechanisms of insulin secretion. Physiol Rev. 1987 Oct;67(4):1185–1248. doi: 10.1152/physrev.1987.67.4.1185. [DOI] [PubMed] [Google Scholar]
  33. Rorsman P., Ashcroft F. M., Trube G. Single Ca channel currents in mouse pancreatic B-cells. Pflugers Arch. 1988 Oct;412(6):597–603. doi: 10.1007/BF00583760. [DOI] [PubMed] [Google Scholar]
  34. Rorsman P., Trube G. Calcium and delayed potassium currents in mouse pancreatic beta-cells under voltage-clamp conditions. J Physiol. 1986 May;374:531–550. doi: 10.1113/jphysiol.1986.sp016096. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Rosenberg R. L., Hess P., Tsien R. W. Cardiac calcium channels in planar lipid bilayers. L-type channels and calcium-permeable channels open at negative membrane potentials. J Gen Physiol. 1988 Jul;92(1):27–54. doi: 10.1085/jgp.92.1.27. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Sala S., Matteson D. R. Single-channel recordings of two types of calcium channels in rat pancreatic beta-cells. Biophys J. 1990 Aug;58(2):567–571. doi: 10.1016/S0006-3495(90)82400-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Sanguinetti M. C., Krafte D. S., Kass R. S. Voltage-dependent modulation of Ca channel current in heart cells by Bay K8644. J Gen Physiol. 1986 Sep;88(3):369–392. doi: 10.1085/jgp.88.3.369. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Smith P. A., Rorsman P., Ashcroft F. M. Modulation of dihydropyridine-sensitive Ca2+ channels by glucose metabolism in mouse pancreatic beta-cells. Nature. 1989 Nov 30;342(6249):550–553. doi: 10.1038/342550a0. [DOI] [PubMed] [Google Scholar]
  39. Wilson D. L., Morimoto K., Tsuda Y., Brown A. M. Interaction between calcium ions and surface charge as it relates to calcium currents. J Membr Biol. 1983;72(1-2):117–130. doi: 10.1007/BF01870319. [DOI] [PubMed] [Google Scholar]
  40. Worley J. F., 3rd, French R. J., Pailthorpe B. A., Krueger B. K. Lipid surface charge does not influence conductance or calcium block of single sodium channels in planar bilayers. Biophys J. 1992 May;61(5):1353–1363. doi: 10.1016/S0006-3495(92)81942-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Yue D. T., Backx P. H., Imredy J. P. Calcium-sensitive inactivation in the gating of single calcium channels. Science. 1990 Dec 21;250(4988):1735–1738. doi: 10.1126/science.2176745. [DOI] [PubMed] [Google Scholar]
  42. Yue D. T., Marban E. Permeation in the dihydropyridine-sensitive calcium channel. Multi-ion occupancy but no anomalous mole-fraction effect between Ba2+ and Ca2+. J Gen Physiol. 1990 May;95(5):911–939. doi: 10.1085/jgp.95.5.911. [DOI] [PMC free article] [PubMed] [Google Scholar]

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