Summary
Isolated nerve cells fromLymnaea stagnalis were studied using the internal-perfusion and patch-clamp techniques. Patch excision frequently activated a voltage-independent Ba2+-permeable channel with a slope conductance of 27 pS at negative potentials (50mm Ba2+). This channel is not seen in patches on healthy cells and, unlike the voltage-dependent Ca channel, is not labile in isolated patches. The activity of the channel in inside-out patches is unaffected by intracellular ATP, Ca2+ below 1mm or the catalytic subunit of cAMP-dependent protein kinase but is reversibly blocked by millimolar intracellular Ca2+ or Ba2+. The channel can be activated in on-cell patches by either internal perfusion with high Ca2+ or the long-term internal perfusion of low Ca2+ solutions not containing ATP. These channels may carry the inward Ca2+ current which causes a regenerative increase in intracellular Ca+ when snail neurons are perfused with high Ca2+ solutions. High internal Ca2+, or long periods of internal perfusion with ATP-free solutions, induces an increase in a resting (−50 mV) whole-cell Ba2+ conductance. This conductance can be turned off by returning the intracellular perfusate to a low Ca2+ solution containing ATP and Mg2+. The activity of this channel appears to have an opposite dependence on intracellular conditions to that of the voltage-dependent Ca channel.
Similar content being viewed by others
References
Beaugé, L., DiPolo, R., Osses, L., Barnola, F., Campos, M. 1981. A (Ca2+, Mg2+)-ATPase activity in plasma membrane fragments isolated from squid nerves.Biochim. Biophys. Acta 644:147–152
Berridge, M.J., Irvine, R.F. 1984. Inositol trisphosphate a novel second messenger in cellular signal transduction.Nature (London) 312:315–321
Byerly, L., Moody, W.J. 1984. Intracellular calcium ions and calcium currents in perfused neurones of the snail,Lymnaea stagnalis.J. Physiol. (London) 352:637–652
Byerly, L., Yazejian, B. 1986. Intracellular factors for the maintenance of calcium currents in perfused neurones from the snail,Lymnaea stagnalis.J. Physiol. (London) 370:631–650
Chesnoy-Marchais, D. 1985. Kinetic properties and selectivity of calcium-permeable single channels inAplysia neurones.J. Physiol. (London) 367:457–488
Colquhoun, D., Neher, E., Reuter, H., Stevens, C.F. 1981. Inward current channels activated by intracellular Ca in cultured cardiac cells.Nature (London) 294:752–754
Connor, J.A., Ahmed, Z. 1984. Diffusion of ions and indicator dyes in neuronal cytoplasm.Cell. Molec. Neurobiol. 4:53–66
Coyne, M.D., Dagan, D., Levitan, I.B. 1987. Calcium and barium permeable channels fromAplysia nervous system reconstituted in lipid bilayers.J. Membrane Biol. 97:205–213
Fink, L., Connor, J. A., Kaczmarek, L.K. 1987. Inositol trisphosphate activates K+ channels through elevation of intracellular calcium in peptidergic neurons ofAplysia.Soc. Neurosci. Abstr. 17:152
Hagiwara, S., Byerly, L. 1981. Calcium channel.Annu. Rev. Neurosci. 4:69–125
Hamill, O.P., Marty, A., Neher, E., Sakmann, B., Sigworth, F.J. 1981. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.Pfluegers Arch. 391:85–100
Kaczmarek, L.K. 1986. Phorbol esters, protein phosphorylation and the regulation of neuronal ion channels.J. Exp. Biol. 124:375–392
Klee, C.B., Crouch, T.H., Krinks, M.H. 1979. Calcineurin: A calcium and calmodulin-binding protein of the nervous system.Proc. Natl. Acad. Sci. USA 76:6270–6273
Kramer, R.H., Zucker, R.S. 1985. Calcium-dependent inward current inAplysia bursting pace-maker neurones.J. Physiol. (London) 362:107–130
Krishtal, O.A., Pidoplichko, V.I. 1975. Intracellular perfusion ofHelix giant neurons.Neirofiziologiya 7:327–329 (translated in: Neurophysiology 7:258–259 (1976))
Kuno, M., Gardner, P. 1987. Ion channels activated by inositol 1,4,5-trisphosphate in plasma membrane of human T-lymphocytes.Nature (London) 326:301–304
Marty, A. 1981: Ca-dependent K channels with large unitary conductance in chromaffin cell membranes.Nature (London) 291:497–500
Partridge, L.D., Swandulla, D. 1987. Single Ca-activated cation channels in bursting neurons ofHelix.Pfluegers Arch. 410:627–631
Partridge, L.D., Swandulla, D. 1988. Calcium-activated nonspecific cation channels.Trends Neurosci. 11:69–72
Shuster, M.J., Camardo, J.S., Siegelbaum, S.A., Kandel, E.R. 1985. Cyclic AMP-dependent protein kinase closes the serotinin-sensitive K+ channels ofAplysia sensory neurones in cell-free membrane patches.Nature (London) 313:392–395
Strong, J.A., Fox, A.P., Tsien, R.W., Kaczmarek, L.K. 1987. Formation of cell-free patches unmasks a large divalent-permeable, voltage-independent channel inAplysia neurons.Soc. Neurosci. Abstr. 13:1011
Swandulla, D., Lux, H.D. 1985. Activation of a nonspecific cation conductance by intracellular Ca2+ elevation in bursting pacemaker neurons ofHelix pomatia.J. Neurophys. 54:1430–1443
Tscharner, V. von, Prod'hom, B., Baggiolini, M., Reuter, H. 1986. Ion channels in human neutrophils activated by a rise in free cytosolic calcium concentration.Nature (London) 324:369–372
Tsien, R.W. 1983. Calcium channels in excitable membranes.Annu. Rev. Physiol. 45:341–358
Wilson, W.A., Jones, L.S., Lewis, D. 1986. Calcium-activated inward current in aplysia non-bursting neurons: Evidence for a nonselective cationic conductance.Soc. Neurosci. Abstr. 16:1200
Yazejian, B., Byerly, L. 1987. Single channel Ba currents in neurons of the snail,Lymnaea stagnalis.Biophys. J. 51:423a
Yellen, G. 1982. Single Ca2+-activated nonselective cation channels in neuroblastoma.Nature (London) 296:357–359
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yazejian, B., Byerly, L. Voltage-independent barium-permeable channel activated inLymnaea neurons by internal perfusion or patch excision. J. Membrain Biol. 107, 63–75 (1989). https://doi.org/10.1007/BF01871084
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01871084