Role of RyRs and IP3 receptors after traumatic injury to spinal cord white matter

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Calcium influx and elevation of intracellular free calcium (Ca2+ i), with subsequent activation of degenerative enzymes is hypothesized to cause cell injury and death after trauma. We examined the effects of traumatic compressive injury on (Ca2+)i dynamics in spinal cord white matter. We conducted electrophysiological studies with ryanodine and inositol (1,4,5)-triphosphate (IP3) receptor agonists and antagonists in an in vitro model of spinal cord injury (SCI). A 25-30-mm length of dorsal column was isolated from the spinal cord of adult rats, pinned in an in vitro recording chamber (37°C) and injured with a modified clip (2-g closing force) for 15 sec. The functional integrity of the dorsal column was monitored electrophysiologically by quantitatively measuring the compound action potential (CAP) with glass microelectrodes. The CAP decreased to 55.2 ± 6.8 % of control (p < 0.05) after spinal cord injury (SCI). Chelation of Ca2+ i with BAPTA-AM (a high-affinity calcium chelator) promoted significantly greater recovery of CAP amplitude (83.2 ± 4.2% of control; p < 0.05) after injury. Infusion of caffeine (1 and 10 mM) exacerbated CAP amplitude decline (45.1 ± 5.9% of control; p < 0.05; 44.6 ± 3.1% of control; p < 0.05) postinjury. Blockade of Ca2+ i release through ryanodine-sensitive receptors (RyRs) with dantrolene (10 μM) and ryanodine (50 μM), conferred significant (p < 0.05) improvement in CAP amplitude after injury. On the other hand, blockade of Ca2+ i with inositol (1,4,5)-triphosphate receptor (IP3Rs) blocker 2APB (10 μM) also conferred significant improvement in CAP amplitude after injury (82.9 ± 7.9%; p < 0.05). In conclusion, the injurious effects of Ca2+ i in traumatic central nervous system (CNS) white matter injury appear to be mediated both by RyRs and through IP3Rs calcium-induced calcium release receptors (CICRs).

Original languageEnglish (US)
Pages (from-to)335-342
Number of pages8
JournalJournal of Neurotrauma
Volume19
Issue number3
DOIs
StatePublished - Jan 1 2002

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Inositol 1,4,5-Trisphosphate Receptors
Ryanodine Receptor Calcium Release Channel
Spinal Cord Injuries
Action Potentials
Wounds and Injuries
Ryanodine
Calcium
Spinal Cord
Dantrolene
Calcium-Sensing Receptors
Enzyme Activation
Inositol 1,4,5-Trisphosphate
Microelectrodes
White Matter
Caffeine
Surgical Instruments
Glass
Cell Death
Central Nervous System

Keywords

  • Astrocytes
  • Axons
  • Glia
  • IP3
  • Oligodendrocytes
  • Rat, ryanodine

ASJC Scopus subject areas

  • Clinical Neurology

Cite this

Role of RyRs and IP3 receptors after traumatic injury to spinal cord white matter. / Thorell, William E; Leibrock, L. G.; Agrawal, Sandeep Kumar.

In: Journal of Neurotrauma, Vol. 19, No. 3, 01.01.2002, p. 335-342.

Research output: Contribution to journalArticle

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AB - Calcium influx and elevation of intracellular free calcium (Ca2+ i), with subsequent activation of degenerative enzymes is hypothesized to cause cell injury and death after trauma. We examined the effects of traumatic compressive injury on (Ca2+)i dynamics in spinal cord white matter. We conducted electrophysiological studies with ryanodine and inositol (1,4,5)-triphosphate (IP3) receptor agonists and antagonists in an in vitro model of spinal cord injury (SCI). A 25-30-mm length of dorsal column was isolated from the spinal cord of adult rats, pinned in an in vitro recording chamber (37°C) and injured with a modified clip (2-g closing force) for 15 sec. The functional integrity of the dorsal column was monitored electrophysiologically by quantitatively measuring the compound action potential (CAP) with glass microelectrodes. The CAP decreased to 55.2 ± 6.8 % of control (p < 0.05) after spinal cord injury (SCI). Chelation of Ca2+ i with BAPTA-AM (a high-affinity calcium chelator) promoted significantly greater recovery of CAP amplitude (83.2 ± 4.2% of control; p < 0.05) after injury. Infusion of caffeine (1 and 10 mM) exacerbated CAP amplitude decline (45.1 ± 5.9% of control; p < 0.05; 44.6 ± 3.1% of control; p < 0.05) postinjury. Blockade of Ca2+ i release through ryanodine-sensitive receptors (RyRs) with dantrolene (10 μM) and ryanodine (50 μM), conferred significant (p < 0.05) improvement in CAP amplitude after injury. On the other hand, blockade of Ca2+ i with inositol (1,4,5)-triphosphate receptor (IP3Rs) blocker 2APB (10 μM) also conferred significant improvement in CAP amplitude after injury (82.9 ± 7.9%; p < 0.05). In conclusion, the injurious effects of Ca2+ i in traumatic central nervous system (CNS) white matter injury appear to be mediated both by RyRs and through IP3Rs calcium-induced calcium release receptors (CICRs).

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