Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1992 May;450:409–435. doi: 10.1113/jphysiol.1992.sp019134

Dopamine D2 receptor stimulation differentially affects voltage-activated calcium channels in rat pituitary melanotropic cells.

J A Keja 1, J C Stoof 1, K S Kits 1
PMCID: PMC1176129  PMID: 1359124

Abstract

1. Whole-cell voltage clamp recordings were made from 141 rat pituitary melanotropic cells in short-term, serum-free, primary culture. The effects of the dopamine D2 receptor agonist, LY 171555, on sodium, potassium and barium currents were investigated. 2. Application of 1 microM-LY 171555 did not affect the inward sodium and outward potassium currents. 3. Application of LY 171555 reversibly inhibited barium currents, with the strongest inhibition on the early inward current. The effect was dose dependent (IC50 = 4 x 10(-8) M), maximal inhibition of the total current was 30% and the LY 171555-induced block (1 microM) was reversibly antagonized by (+/-)sulpiride (4 microM). 4. Using barium-selective saline solutions, different types of barium current (T, N, and two L components) were identified on the basis of their voltage-dependent kinetics. Their relative amplitudes differed between cells. 5. The T-type current activated at potentials positive to -60 mV, reaching peak amplitude between -20 and -10 mV. At -30 mV, this current was inhibited up to 30% by 1 microM-LY 171555. The time constants of activation (10-3 ms) and inactivation (50-20 ms) as well as the voltage dependence of inactivation (potential of half-maximal inactivation (H), -61 mV; slope factor (S), 4.9 mV) were not affected by LY 171555 application. 6. A rapidly inactivating (time constants 100-50 ms), high threshold current component was identified as an N-type current. This current activated at command potentials positive to -30 mV and reached a maximal amplitude at +10 mV. The steady-state inactivation was described by a single Boltzmann equation with H = -65 mV and S = 11.7 mV. Application of 1 microM-LY 171555 completely suppressed this current. 7. The slowly inactivating (time constants > 1500 ms), high-threshold, L-type current displayed the same voltage dependence of activation as the N current. The voltage dependence of inactivation was modelled by the sum of two Boltzmann equations (L1: H1 = -45 mV, S1 = 13.0 mV; L2:H2 = -11 mV, S2 = 6.0 mV), indicating the existence of two L channel populations. Neither time course, nor voltage dependence of inactivation were influenced by LY 171555. However, LY 171555 induced a slow-down in the time course of activation, which necessitated the use of two time constants to model the activation kinetics. One of these (approximately 2 ms) was also observed under control conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Full text

PDF
409

Selected References

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

  1. Armstrong D., Eckert R. Voltage-activated calcium channels that must be phosphorylated to respond to membrane depolarization. Proc Natl Acad Sci U S A. 1987 Apr;84(8):2518–2522. doi: 10.1073/pnas.84.8.2518. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bean B. P. Classes of calcium channels in vertebrate cells. Annu Rev Physiol. 1989;51:367–384. doi: 10.1146/annurev.ph.51.030189.002055. [DOI] [PubMed] [Google Scholar]
  3. Bean B. P. Neurotransmitter inhibition of neuronal calcium currents by changes in channel voltage dependence. Nature. 1989 Jul 13;340(6229):153–156. doi: 10.1038/340153a0. [DOI] [PubMed] [Google Scholar]
  4. Carbone E., Lux H. D. Kinetics and selectivity of a low-voltage-activated calcium current in chick and rat sensory neurones. J Physiol. 1987 May;386:547–570. doi: 10.1113/jphysiol.1987.sp016551. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Carbone E., Swandulla D. Neuronal calcium channels: kinetics, blockade and modulation. Prog Biophys Mol Biol. 1989;54(1):31–58. doi: 10.1016/0079-6107(89)90008-4. [DOI] [PubMed] [Google Scholar]
  6. Chen C., Zhang J., Vincent J. D., Israel J. M. Two types of voltage-dependent calcium current in rat somatotrophs are reduced by somatostatin. J Physiol. 1990 Jun;425:29–42. doi: 10.1113/jphysiol.1990.sp018090. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cota G. Calcium channel currents in pars intermedia cells of the rat pituitary gland. Kinetic properties and washout during intracellular dialysis. J Gen Physiol. 1986 Jul;88(1):83–105. doi: 10.1085/jgp.88.1.83. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Douglas W. W., Taraskevich P. S. Action potentials in gland cells of rat pituitary pars intermedia: inhibition by dopamine, an inhibitor of MSH secretion. J Physiol. 1978 Dec;285:171–184. doi: 10.1113/jphysiol.1978.sp012565. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Douglas W. W., Taraskevich P. S. Slowing effects of dopamine and calcium-channel blockers on frequency of sodium spikes in rat pars intermedia cells. J Physiol. 1982 May;326:201–211. doi: 10.1113/jphysiol.1982.sp014186. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Edmonds B., Klein M., Dale N., Kandel E. R. Contributions of two types of calcium channels to synaptic transmission and plasticity. Science. 1990 Nov 23;250(4984):1142–1147. doi: 10.1126/science.2174573. [DOI] [PubMed] [Google Scholar]
  11. 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]
  12. Freedman J. E., Weight F. F. Single K+ channels activated by D2 dopamine receptors in acutely dissociated neurons from rat corpus striatum. Proc Natl Acad Sci U S A. 1988 May;85(10):3618–3622. doi: 10.1073/pnas.85.10.3618. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. García A. G., Sala F., Reig J. A., Viniegra S., Frías J., Fontériz R., Gandía L. Dihydropyridine BAY-K-8644 activates chromaffin cell calcium channels. Nature. 1984 May 3;309(5963):69–71. doi: 10.1038/309069a0. [DOI] [PubMed] [Google Scholar]
  14. 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]
  15. Hirning L. D., Fox A. P., McCleskey E. W., Olivera B. M., Thayer S. A., Miller R. J., Tsien R. W. Dominant role of N-type Ca2+ channels in evoked release of norepinephrine from sympathetic neurons. Science. 1988 Jan 1;239(4835):57–61. doi: 10.1126/science.2447647. [DOI] [PubMed] [Google Scholar]
  16. Hosey M. M., Lazdunski M. Calcium channels: molecular pharmacology, structure and regulation. J Membr Biol. 1988 Sep;104(2):81–105. doi: 10.1007/BF01870922. [DOI] [PubMed] [Google Scholar]
  17. Ikeda S. R., Schofield G. G. Somatostatin blocks a calcium current in rat sympathetic ganglion neurones. J Physiol. 1989 Feb;409:221–240. doi: 10.1113/jphysiol.1989.sp017494. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Keja J. A., Stoof J. C., Kits K. S. Voltage-activated currents through calcium channels in rat pituitary melanotrophic cells. Neuroendocrinology. 1991 Apr;53(4):349–359. doi: 10.1159/000125741. [DOI] [PubMed] [Google Scholar]
  19. Lipscombe D., Kongsamut S., Tsien R. W. Alpha-adrenergic inhibition of sympathetic neurotransmitter release mediated by modulation of N-type calcium-channel gating. Nature. 1989 Aug 24;340(6235):639–642. doi: 10.1038/340639a0. [DOI] [PubMed] [Google Scholar]
  20. Lledo P. M., Legendre P., Israel J. M., Vincent J. D. Dopamine inhibits two characterized voltage-dependent calcium currents in identified rat lactotroph cells. Endocrinology. 1990 Sep;127(3):990–1001. doi: 10.1210/endo-127-3-990. [DOI] [PubMed] [Google Scholar]
  21. Lledo P. M., Legendre P., Zhang J., Israel J. M., Vincent J. D. Effects of dopamine on voltage-dependent potassium currents in identified rat lactotroph cells. Neuroendocrinology. 1990 Dec;52(6):545–555. doi: 10.1159/000125650. [DOI] [PubMed] [Google Scholar]
  22. Marchetti C., Carbone E., Lux H. D. Effects of dopamine and noradrenaline on Ca channels of cultured sensory and sympathetic neurons of chick. Pflugers Arch. 1986 Feb;406(2):104–111. doi: 10.1007/BF00586670. [DOI] [PubMed] [Google Scholar]
  23. Marchetti C., Robello M. Guanosine-5'-O-(3-thiotriphosphate) modifies kinetics of voltage-dependent calcium current in chick sensory neurons. Biophys J. 1989 Dec;56(6):1267–1272. doi: 10.1016/S0006-3495(89)82774-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. May V., Eipper B. A. Long term culture of primary rat pituitary adrenocorticotropin/endorphin-producing cells in serum-free medium. Endocrinology. 1986 Apr;118(4):1284–1295. doi: 10.1210/endo-118-4-1284. [DOI] [PubMed] [Google Scholar]
  25. McBurney R. N., Kehl S. J. Electrophysiology of neurosecretory cells from the pituitary intermediate lobe. J Exp Biol. 1988 Sep;139:317–328. doi: 10.1242/jeb.139.1.317. [DOI] [PubMed] [Google Scholar]
  26. Penington N. J., Kelly J. S. Serotonin receptor activation reduces calcium current in an acutely dissociated adult central neuron. Neuron. 1990 May;4(5):751–758. doi: 10.1016/0896-6273(90)90201-p. [DOI] [PubMed] [Google Scholar]
  27. Plummer M. R., Hess P. Reversible uncoupling of inactivation in N-type calcium channels. Nature. 1991 Jun 20;351(6328):657–659. doi: 10.1038/351657a0. [DOI] [PubMed] [Google Scholar]
  28. Rane S. G., Holz G. G., 4th, Dunlap K. Dihydropyridine inhibition of neuronal calcium current and substance P release. Pflugers Arch. 1987 Aug;409(4-5):361–366. doi: 10.1007/BF00583789. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Stanley E. F., Russell J. T. Inactivation of calcium channels in rat pituitary intermediate lobe cells. Brain Res. 1988 Dec 13;475(1):64–72. doi: 10.1016/0006-8993(88)90199-0. [DOI] [PubMed] [Google Scholar]
  30. Stockbridge N. EGTA. Comput Biol Med. 1987;17(5):299–304. doi: 10.1016/0010-4825(87)90019-9. [DOI] [PubMed] [Google Scholar]
  31. Takahashi K., Wakamori M., Akaike N. Hippocampal CA1 pyramidal cells of rats have four voltage-dependent calcium conductances. Neurosci Lett. 1989 Sep 25;104(1-2):229–234. doi: 10.1016/0304-3940(89)90359-5. [DOI] [PubMed] [Google Scholar]
  32. Taleb O., Trouslard J., Demeneix B. A., Feltz P. Characterization of calcium and sodium currents in porcine pars intermedia cells. Neurosci Lett. 1986 May 6;66(1):55–60. doi: 10.1016/0304-3940(86)90165-5. [DOI] [PubMed] [Google Scholar]
  33. Taraskevich P. S., Douglas W. W. Effects of Bay K 8644 and other dihydropyridines on basal and potassium-evoked output of MSH from mouse melanotrophs in vitro. Neuroendocrinology. 1986;44(3):384–389. doi: 10.1159/000124673. [DOI] [PubMed] [Google Scholar]
  34. Thomas P., Surprenant A., Almers W. Cytosolic Ca2+, exocytosis, and endocytosis in single melanotrophs of the rat pituitary. Neuron. 1990 Nov;5(5):723–733. doi: 10.1016/0896-6273(90)90226-6. [DOI] [PubMed] [Google Scholar]
  35. Thornton V. F. Stimulation of calcium-dependent release of labelled protein from pulse-labelled mouse pituitary intermediate lobe tissue. J Physiol. 1982 Aug;329:425–437. doi: 10.1113/jphysiol.1982.sp014311. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Trouslard J., Demeneix B. A., Feltz P. Spontaneous spiking activities of porcine pars intermedia cells: effects of thyrotropin-releasing hormone. Neuroendocrinology. 1989 Jul;50(1):33–43. doi: 10.1159/000125199. [DOI] [PubMed] [Google Scholar]
  37. Tsuruta K., Frey E. A., Grewe C. W., Cote T. E., Eskay R. L., Kebabian J. W. Evidence that LY-141865 specifically stimulates the D-2 dopamine receptor. Nature. 1981 Jul 30;292(5822):463–465. doi: 10.1038/292463a0. [DOI] [PubMed] [Google Scholar]
  38. Williams P. J., MacVicar B. A., Pittman Q. J. A dopaminergic inhibitory postsynaptic potential mediated by an increased potassium conductance. Neuroscience. 1989;31(3):673–681. doi: 10.1016/0306-4522(89)90432-6. [DOI] [PubMed] [Google Scholar]
  39. Williams P. J., MacVicar B. A., Pittman Q. J. Electrophysiological properties of neuroendocrine cells of the intact rat pars intermedia: multiple calcium currents. J Neurosci. 1990 Mar;10(3):748–756. doi: 10.1523/JNEUROSCI.10-03-00748.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Williams P. J., MacVicar B. A., Pittman Q. J. Synaptic modulation by dopamine of calcium currents in rat pars intermedia. J Neurosci. 1990 Mar;10(3):757–763. doi: 10.1523/JNEUROSCI.10-03-00757.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]

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

RESOURCES