52 modification of brain cell membrane na+ ,k+-atpase following recovery from severe from severe ischemic and hypercanic injury in newborn piglets

ABSTRACT The present study tests the hypothesis that changes in the brain cell membrane Na+, K+-ATPase are reflected in the kinetic characteristics of the enzyme molecule and are specific to

the active sites for ATP, Na+, K+ and strophanthidin. Studies were performed in 7 normoxemic piglets hyperventilated to PaCO2 of 8± 1 mmHg for 1 hr and allowed to recover for 6 hrs

(ischemic injury) and 8 normoxemic piglets with administration of 7% CO2 for 90 min (PaCO2 84±7 mmHg) followed by 2 hrs recovery (hypercapnic injury). Brain cell membranes were prepared and

the affinities of the Na+.K+-ATPase for ATP, K+, Na+(Km in mM) and strophanthidin (IC50 in mM) were determined in the hypo- and hypercapnic states, and their respective recoveries and

compared to control. For ATP, Km decreases from 0.78±0.15 in controls to 0.62±0.11 during hypocapnia and 0.61 ±0.12 during hypercapnia; for K+ the Km changes from 2.36±0.56 in controls to

4.06 ± 0.37 during hypocapnia and 1.13±0.09 during hypercapnia, and for Na+ the Km increases from 5.43 ±0.57 in controls to 8.33±0.72 during hypocapnia and 6.97±0.41 during hypercapnia. The

IC50 for strophanthidin decreases from 1×10−6M in controls to 6×10−7 M during hypocapnia and 7×10−7 M during hypercapnia. The recovery phases yielded affinities which were not statistically

different from the experimental conditions. These results indicate that the active sites of Na+, K+-ATPase are modified during hypo- and hypercapnia. The differential alteration of the

affinity for K+ suggests that during ischemia, dephosphorylalion and therefore energy release are decreased, while hypercapnia favors enzyme dephosphorylation. We suggest that the K+ site is

the critical regulatory site for enzyme function in brain cell membranes of newborn piglets. ARTICLE PDF AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * University of Pennsylvania School of

Medicine, Dept. of Physiology, Philadelphia, PA Roy Schneiderman, O P Mishra, Johanna Kubin & Maria Delivoria-Papadopoulos Authors * Roy Schneiderman View author publications You can

also search for this author inPubMed Google Scholar * O P Mishra View author publications You can also search for this author inPubMed Google Scholar * Johanna Kubin View author publications

You can also search for this author inPubMed Google Scholar * Maria Delivoria-Papadopoulos View author publications You can also search for this author inPubMed Google Scholar RIGHTS AND

PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Schneiderman, R., Mishra, O., Kubin, J. _et al._ 52 MODIFICATION OF BRAIN CELL MEMBRANE Na+ ,K+-ATPASE FOLLOWING

RECOVERY FROM SEVERE FROM SEVERE ISCHEMIC AND HYPERCANIC INJURY IN NEWBORN PIGLETS. _Pediatr Res_ 30, 636 (1991). https://doi.org/10.1203/00006450-199112000-00082 Download citation * Issue

Date: 01 December 1991 * DOI: https://doi.org/10.1203/00006450-199112000-00082 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get shareable

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