Effect of nitric oxide synthase inhibition on high affinity Ca(2+)-ATPase during hypoxia in cerebral cortical neuronal nuclei of newborn piglets.
Previous studies have shown that during hypoxia, neuronal nuclear high affinity Ca(2+)-ATPase activity is increased in the cerebral cortex of newborn piglets. The present study tests the hypothesis that pretreatment with N-nitro-L-arginine (NNLA) will prevent the hypoxia-induced increase in high affinity Ca(2+)-ATPase activity in cortical neuronal nuclear membrane of newborn piglets. We also tested the hypothesis that nitration is a mechanism of elevation of the high affinity Ca(2+)-ATPase activity during hypoxia. Studies were performed in five normoxic, five hypoxic, and six NNLA-pretreated (40 mg/kg) hypoxic newborn piglets. Cerebral cortical neuronal nuclei were isolated and the high affinity Ca(2+)-ATPase activity was determined. Further, normoxic samples were aliquoted into two sub-groups for in vitro nitration with 0.5 mM peroxynitrite and subsequent determination of the high affinity Ca(2+)-ATPase activity. The activity increased from 309+/-40 nmol Pi/mg protein/h in the normoxic group to 520+/-108 nmol Pi/mg protein/h in the hypoxic group (P<0.05). In the NNLA-pretreated group, the activity was 442+/-53 nmol Pi/mg protein/h (P<0.05), which is 25% lower than in the hypoxic group. In the nitrated group the enzyme activity increased to 554+/-59 nmol Pi/mg protein/h (P<0. 05). Thus peroxynitrite-induced nitration in vitro increased the high affinity Ca(2+)-ATPase activity and NNLA administration in vivo partially prevented the hypoxia-induced increase in neuronal nuclear high affinity Ca(2+)-ATPase activity. We conclude that the hypoxia-induced increase in nuclear membrane high affinity Ca(2+)-ATPase activity is NO-mediated and that nitration of the enzyme is a mechanism of its modification.
Gavini
G
G
Department of Pediatrics/Neonatology, MCP Hahnemann University and St. Christopher's Hospital for Children, 3300 Henry Avenue, 7th Floor, Room #701, Philadelphia, PA 19129, USA. mishra@drexel.edu
Zanelli
S A
SA
Ashraf
Q M
QM
Mishra
O P
OP
Delivoria-Papadopoulos
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002540:Cerebral Cortex / Q000201:enzymology*; D002534:Hypoxia, Brain / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D019335:Nitroarginine / Q000494:pharmacology*; D009685:Nuclear Envelope / Q000201:enzymology*; D010725:Phosphocreatine / Q000378:metabolism; D013552:Swine
D010725:Phosphocreatine; D019335:Nitroarginine; D000255:Adenosine Triphosphate; D019001:Nitric Oxide Synthase; D000252:Calcium-Transporting ATPases