Involvement of nitric oxide in the deregulation of cytosolic calcium in cerebellar neurons during combined glucose-oxygen deprivation

Mol Chem Neuropathol. 1996 Feb;27(2):155-66. doi: 10.1007/BF02815091.

Abstract

Nitric oxide (NO) has been proposed as a neuronal messenger molecule in hypoxic/ischemic cell injury (Nowicki et al., 1991; Trifiletti, 1992). We conducted studies in a model of combined glucose-oxygen deprivation using cultured rat cerebellar granule cells. Experiments were designed to test the hypothesis that sustained elevation of cytosolic calcium ([Ca2+]i) and NO generation act in concert to trigger neuronal injury after anoxic insult. A hypoxic state was achieved by perfusing the cells with medium pre-equilibrated with argon gas. [Ca2+]i was monitored using digital-imaging fluorescence microscopy in cells loaded with fura-2 AM. Under short-term hypoxic conditions, cells displayed a progressive and sustained, moderate increase of [Ca2+]i, which returned to near basal levels on restoration of O2-containing medium. Prolonged hypoxic conditions (> 60 min) caused irreversible elevation of [Ca2+]i followed by disruption of cell membrane integrity, as indicated by severe swelling, loss of regular cell shape and processes, leakage of dye fura-2, and propidium iodide uptake ("point of no return"). Pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 100 microM), a specific NO synthase inhibitor, markedly delayed the onset of intensity of the rise of [Ca2+]i. The hypoxia-induced elevation of [Ca2+]i was also greatly attenuated if L-NAME (100 microM) was added to the argon-perfused medium before the cells demonstrated signs of irreversible injury. Prolonged or repeated hypoxic conditions, however, caused a rapid and intense increase of [Ca2+]i, which could not be blocked by inhibition of NO synthase (NOS). In addition, reoxygenation after the "point of no return," as characterized above, greatly potentiated [Ca2+]i overload and facilitated the process of cell injury. The potentiation and facilitation of cell damage, as demonstrated by rapid massive increase of [Ca2+]i and subsequent cell death, was not blocked by NOS inhibitor, L-NAME.

MeSH terms

  • Animals
  • Calcium / antagonists & inhibitors*
  • Calcium / metabolism*
  • Cells, Cultured
  • Cerebellum / drug effects*
  • Glucose / deficiency*
  • Hypoxia / chemically induced
  • Hypoxia / pathology*
  • Hypoxia / therapy
  • NG-Nitroarginine Methyl Ester / pharmacology
  • Neurons / drug effects*
  • Nitric Oxide / pharmacology*
  • Nitric Oxide Synthase / antagonists & inhibitors
  • Oxidative Stress / drug effects
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Nitric Oxide
  • Nitric Oxide Synthase
  • Glucose
  • Calcium
  • NG-Nitroarginine Methyl Ester