Role of calcium in inactivation of calcium/calmodulin dependent protein kinase II after cerebral ischemia.
Transient cerebral ischemia demonstrates an increase in activated oxygen species in the brain that could lead to eventual neuronal cell death. Neuronal cells respond to oxygen free radicals through the restructuring of the cytoskeleton and membranes, mobilization of calcium and gene expression which play a role in cell injury. Ten min of bilateral carotid artery occlusion resulted in a decrease in calcium/calmodulin dependent protein kinase II (CaM kinase II) phosphorylation and activity detected in the brain immediately following ischemia and was partially restored within 24 h of reperfusion. Pretreatment of animals with an anesthetic dose of pentobarbital (40 mg/kg) resulted in partial protection of inactivation of CaM kinase II following ischemia. CaM kinase II activity was maintained following pretreatment of animals with alpha-phenyl N-tert-butyl nitrone (PBN), which traps oxygen free radicals. Infusion of superoxide dismutase or catalase prior to ischemia, blocked CaM kinase II inactivation. Blockage of calcium uptake with bepridil resulted in a marked protection of CaM kinase II inactivation. In addition, trifluoperazine, a calmodulin antagonist also diminished the inhibition of CaM kinase II phosphorylation in our model. These results suggest that ischemia and reperfusion injury results in the generation of activated oxygen and the mobilization of calcium which inactivate CaM kinase II. These results indicate that changes associated with protein kinase activity in the brain following an ischemic insult may have profound effects upon neurodegeneration and neuronal survival.
Hiestand
D M
DM
Department of Biochemistry, Chandler Medical Center, The University of Kentucky, Lexington 40536-0084.
Haley
B E
BE
Kindy
M S
MS
D000818:Animals; D002545:Brain Ischemia / Q000201:enzymology* / Q000378:metabolism / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004789:Enzyme Activation / Q000187:drug effects; D005849:Gerbillinae; D008297:Male; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000494:pharmacology; D013997:Time Factors
D017382:Reactive Oxygen Species; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium