Distinct Omega-agatoxin-sensitive Calcium Currents in Somata and Axon Terminals of Rat Supraoptic Neurones

Overview

Journal J Physiol

Specialty Physiology

Date 1995 Dec 1

PMID 8847634

Citations 18

Authors

T E Fisher

C W Bourque

Affiliations

Soon will be listed here.

Abstract

1. Voltage-dependent calcium currents were measured at room temperature using whole-cell patch clamp in acutely isolated somata and axon terminals of the magnocellular neurosecretory cells (MNCs) from the rat supraoptic nucleus. 2. Administration of omega-agatoxin IVA (omega-Aga IVA) blocked a high-threshold non-inactivating current. This current has an IC50 for omega-Aga IVA of 3 nM; no other types of currents were blocked at doses of up to 500 nM. 3. In the axon terminals omega-Aga IVA blocked a high-threshold current that inactivates markedly (tau approximately 448 ms), and has a much lower sensitivity to the toxin, with an IC50 of 270 nM. Unlike the somatic current, the effect of omega-Aga IVA in the terminals is largely prevented by omega-conotoxin GVIA (omega-CgTX). 4. These data suggest that MNC somata express a single type of omega-Aga IVA-sensitive calcium current similar to the P-type calcium current described in other cells. However, the omega-Aga IVA-sensitive current in axon terminals differs from both the P-type and the recently identified Q-type current in that it is also sensitive to omega-CgTX. The distinct biophysical properties of the currents in somata and axon terminals may have important physiological implications.

Citing Articles

Venom-Derived Peptides Inhibiting Voltage-Gated Sodium and Calcium Channels in Mammalian Sensory Neurons.

Yousuf A, Sadeghi M, Adams D Adv Exp Med Biol. 2022; 1349:3-19.

PMID: 35138607 DOI: 10.1007/978-981-16-4254-8_1.

Presynaptic voltage-gated calcium channels in the auditory brainstem.

Young Jr S, Veeraraghavan P Mol Cell Neurosci. 2021; 112:103609.

PMID: 33662542 PMC: 8085099. DOI: 10.1016/j.mcn.2021.103609.

Expression and functions of N-type Cav2.2 and T-type Cav3.1 channels in rat vasopressin neurons under normotonic conditions.

Sato-Numata K, Numata T, Ueta Y, Okada Y J Physiol Sci. 2020; 70(1):49.

PMID: 33059597 PMC: 10717235. DOI: 10.1186/s12576-020-00775-w.

Electrophysiological properties of identified oxytocin and vasopressin neurones.

Armstrong W, Foehring R, Kirchner M, Sladek C J Neuroendocrinol. 2018; 31(3):e12666.

PMID: 30521104 PMC: 7251933. DOI: 10.1111/jne.12666.

The Ca2+ channel β2 subunit is selectively targeted to the axon terminals of supraoptic neurons.

Wang D, Bansal V, Fisher T Channels (Austin). 2014; 8(3):216-21.

PMID: 24755552 PMC: 4203750. DOI: 10.4161/chan.28863.

References

Llinas R, Sugimori M . Electrophysiological properties of in vitro Purkinje cell dendrites in mammalian cerebellar slices. J Physiol. 1980; 305:197-213. PMC: 1282967. DOI: 10.1113/jphysiol.1980.sp013358. View

Fisher T, Bourque C . Voltage-gated calcium currents in the magnocellular neurosecretory cells of the rat supraoptic nucleus. J Physiol. 1995; 486 ( Pt 3):571-80. PMC: 1156547. DOI: 10.1113/jphysiol.1995.sp020835. View

Bourque C . Calcium-dependent spike after-current induces burst firing in magnocellular neurosecretory cells. Neurosci Lett. 1986; 70(2):204-9. DOI: 10.1016/0304-3940(86)90464-7. View

Bourque C, Brown D, Renaud L . Barium ions induce prolonged plateau depolarizations in neurosecretory neurones of the adult rat supraoptic nucleus. J Physiol. 1986; 375:573-86. PMC: 1182776. DOI: 10.1113/jphysiol.1986.sp016134. View

Andrew R . Endogenous bursting by rat supraoptic neuroendocrine cells is calcium dependent. J Physiol. 1987; 384:451-65. PMC: 1192271. DOI: 10.1113/jphysiol.1987.sp016463. View

Bicknell R . Optimizing release from peptide hormone secretory nerve terminals. J Exp Biol. 1988; 139:51-65. DOI: 10.1242/jeb.139.1.51. View

Llinas R, Sugimori M, Lin J, Cherksey B . Blocking and isolation of a calcium channel from neurons in mammals and cephalopods utilizing a toxin fraction (FTX) from funnel-web spider poison. Proc Natl Acad Sci U S A. 1989; 86(5):1689-93. PMC: 286766. DOI: 10.1073/pnas.86.5.1689. View

Adams M, Bindokas V, Hasegawa L, Venema V . Omega-agatoxins: novel calcium channel antagonists of two subtypes from funnel web spider (Agelenopsis aperta) venom. J Biol Chem. 1990; 265(2):861-7. View

Lemos J, Nowycky M . Two types of calcium channels coexist in peptide-releasing vertebrate nerve terminals. Neuron. 1989; 2(5):1419-26. DOI: 10.1016/0896-6273(89)90187-6. View

10.

Mori Y, Friedrich T, Kim M, Mikami A, Nakai J, Ruth P . Primary structure and functional expression from complementary DNA of a brain calcium channel. Nature. 1991; 350(6317):398-402. DOI: 10.1038/350398a0. View

11.

Tsien R, Ellinor P, Horne W . Molecular diversity of voltage-dependent Ca2+ channels. Trends Pharmacol Sci. 1991; 12(9):349-54. DOI: 10.1016/0165-6147(91)90595-j. View

12.

Nowycky M . Two high-threshold Ca2+ channels contribute Ca2+ for depolarization-secretion coupling in the mammalian neurohypophysis. Ann N Y Acad Sci. 1991; 635:45-57. DOI: 10.1111/j.1749-6632.1991.tb36480.x. View

13.

Mintz I, Adams M, Bean B . P-type calcium channels in rat central and peripheral neurons. Neuron. 1992; 9(1):85-95. DOI: 10.1016/0896-6273(92)90223-z. View

14.

Wang X, Treistman S, Lemos J . Two types of high-threshold calcium currents inhibited by omega-conotoxin in nerve terminals of rat neurohypophysis. J Physiol. 1992; 445:181-99. PMC: 1179977. DOI: 10.1113/jphysiol.1992.sp018919. View

15.

Takahashi T, Momiyama A . Different types of calcium channels mediate central synaptic transmission. Nature. 1993; 366(6451):156-8. DOI: 10.1038/366156a0. View

16.

Wheeler D, Randall A, Tsien R . Roles of N-type and Q-type Ca2+ channels in supporting hippocampal synaptic transmission. Science. 1994; 264(5155):107-11. DOI: 10.1126/science.7832825. View

17.

Lundy P, Hamilton M, Frew R . Pharmacological identification of a novel Ca2+ channel in chicken brain synaptosomes. Brain Res. 1994; 643(1-2):204-10. DOI: 10.1016/0006-8993(94)90026-4. View

18.

Stea A, TOMLINSON W, Soong T, Bourinet E, DUBEL S, Vincent S . Localization and functional properties of a rat brain alpha 1A calcium channel reflect similarities to neuronal Q- and P-type channels. Proc Natl Acad Sci U S A. 1994; 91(22):10576-80. PMC: 45064. DOI: 10.1073/pnas.91.22.10576. View

19.

Randall A, Tsien R . Pharmacological dissection of multiple types of Ca2+ channel currents in rat cerebellar granule neurons. J Neurosci. 1995; 15(4):2995-3012. PMC: 6577783. View

20.

Theodosis D, Legendre P, Vincent J, Cooke I . Immunocytochemically identified vasopressin neurons in culture show slow, calcium-dependent electrical responses. Science. 1983; 221(4615):1052-4. DOI: 10.1126/science.6348947. View