Journal
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
Volume 446, Issue 4, Pages 447-454Publisher
SPRINGER-VERLAG
DOI: 10.1007/s00424-003-1094-z
Keywords
calcium signalling; InsP(3)R/RyR; endoplasmic reticulum calcium stores; sensory neurones
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We addressed the fundamentally important question of functional continuity of endoplasmic reticulum (ER) Ca2+ store in nerve cells. In cultured rat dorsal root ganglion neurones we measured dynamic changes in free Ca2+ concentration within the ER lumen ([Ca2+](L)) in response to activation of inositol-1,4,5-trisphosphate receptors (InsP(3)Rs) and ryanodine receptors (RyRs). We found that both receptors co-exist in these neurones and their activation results in Ca2+ release from the ER as judged by a decrease in [Ca2+](L). Depletion of Ca2+ stores following an inhibition of sarco(endoplasmic)reticulum Ca2+-ATPase by thapsigargin or cyclopiazonic acid completely eliminated Ca2+ release via both InsP(3)Rs and RyRs. Similarly, when the store was depleted by continuous activation of InsP(3)Rs, activation of RyRs (by caffeine or 0.5 muM ryanodine) failed to produce Ca2+ release, and vice versa, when the stores were depleted by activators of RyRs, the InsP(3)-induced Ca2+ release disappeared. We conclude that in mammalian neurones InsP(3)Rs and RyRs share the common continuous Ca2+ pool associated with ER.
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