Magnesium sulfate effect on erythrocyte membranes of asphyxiated newborns.
OBJECTIVE
Magnesium sulfate has been recognized as a neuroprotective agent against hypoxia-ischemia, mainly by the protection from the excitotoxicity associated with increased glutamate concentration. However, the mechanism of MgSO4 action is not fully understood and is considerably controversial.


METHODS
During the 2 first hours of life, the asphyxiated full-term newborns were treated intravenously with one dose of MgSO4 250 mg/kg body weight. At birth, after 6 and 48 h of life the activity of ATP-dependent enzymes in erythrocyte membranes: Mg2+-ATPase, Ca2+-ATPase, protein kinases A and C, were determined. Using monoclonal antibodies, the band 3 and its phosphotyrosine level were also assayed.


RESULTS
The time-dependent decrease of Ca2+-ATPase activity was detected in untreated newborns, whereas MgSO4 prevented this reduction. After 48 h, protein kinases activities differed in MgSO4-treated and untreated groups. Magnesium therapy increased the amount of band 3 and diminished proteolytic degradation of this protein.


CONCLUSIONS
Our results demonstrated, for the first time, that magnesium sulfate treatment significantly altered the activities of some important enzymes in erythrocyte membrane from asphyxiated newborns. It also reduced the post-asphyxial damages of membrane compounds. These data may partly explain the molecular mechanisms of MgSO4 action in asphyxiated newborns.
Szemraj
Janusz
J
Department of Molecular Neurochemistry, Medical University of Lodz, 6/8 Mazowiecka Str, 92-215 Lodz, Poland.
Sobolewska
Barbara
B
Gulczynska
Ewa
E
Wilczynski
Jan
J
Zylinska
Ludmila
L
D001457:Anion Exchange Protein 1, Erythrocyte / Q000032:analysis; D001238:Asphyxia Neonatorum / Q000188:drug therapy* / Q000201:enzymology; D017301:Ca(2+) Mg(2+)-ATPase / Q000097:blood; D000252:Calcium-Transporting ATPases / Q000097:blood; D017868:Cyclic AMP-Dependent Protein Kinases / Q000097:blood; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D007231:Infant, Newborn; D008274:Magnesium / Q000097:blood; D008278:Magnesium Sulfate / Q000627:therapeutic use*; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D019000:Phosphotyrosine / Q000097:blood; D011493:Protein Kinase C / Q000097:blood
D001457:Anion Exchange Protein 1, Erythrocyte; D018696:Neuroprotective Agents; D019000:Phosphotyrosine; D008278:Magnesium Sulfate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D008274:Magnesium