Activation of Ca2+-dependent currents in cultured rat dorsal root ganglion neurones by a sperm factor and cyclic ADP-ribose

Kevin P.M. Currie, Karl Swann, Antony Galione, Roderick H. Scott

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121 Scopus citations

Abstract

The effects of intracellular application of two novel Ca2+ releasing agents have been studied in cultured rat dorsal root ganglion (DRG) neurones by monitoring Ca2+-dependent currents as a physiological index of raised free cytosolic Ca2+ ([Ca2+]i). A protein based sperm factor (SF) extracted from mammalian sperm, has been found to trigger Ca2+ oscillations and to sensitize unfertilized mammalian eggs to calcium induced calcium release (CICR). In this study intracellular application of SF activated Ca2+-dependent currents in approximately two-thirds of DRG neurones. The SF induced activity was abolished by heat treatment, attenuated by increasing the intracellular Ca2+ buffering capacity of the cells and persisted when extracellular Ca2+ was replaced by Ba2+. In addition, activity could be triggered or potentiated by loading the cells with Ca2+ by activating a series of voltage-gated Ca2+ currents. Ca2+-activated inward current activity was also generated by intracellular application of cyclic ADP-ribose (cADPR), a metabolite of NAD+, which causes Ca2+ release in sea urchin eggs. This activity could also be enhanced by loading the cells with Ca2+. The cADPR induced activity, but not the SF induced activity, was abolished by depleting the caffeine sensitive Ca2+ store. Ruthenium red markedly attenuated SF induced activity but had little action on cADPR induced activity or caffeine induced activity. Our results indicate that both SF and cADPR release intracellular Ca2+ pools in DRG neurones and that they appear to act on subtly distinct stores or distinct intracellular Ca2+ release mechanisms, possibly by modulating CICR.

Original languageEnglish (US)
Pages (from-to)1415-1425
Number of pages11
JournalMolecular biology of the cell
Volume3
Issue number12
DOIs
StatePublished - Dec 1992

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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