Postasphyxial reoxygenation reduces the activity of Na+/K+-ATPase in the erythrocytes of newborn piglets.
The aim of our study was to determine whether the impairment of Na+/K+ pump is detectable in erythrocytes during hypoxia and reoxygenation. Acute asphyxia was induced in 10 newborn piglets for 1 h by bilateral pneumothorax. The Na+/K+-ATPase activity, Na+, K+ and ATP content of RBCs were determined in baseline condition (paO2: 60.4 +/- 9.3 mm Hg), at the end of the hypoxic period (1 h) (paO2: 30.2 +/- 10.3 mm Hg), then hourly during the reoxygenation phase (2, 3, 4 h) (paO2: 54.8 +/- 9.0, 56.1 +/- 8.7, 57.2 +/- 9.6 mm Hg). The Na+/K+-ATPase activity was constant during the first 3 h. However, it decreased at 4 h (676 +/- 168 versus baseline 833 +/- 141 U, p < 0.05). The highest ATP content was measured also at this point (4.32 +/- 0.57 versus baseline 3.27 +/- 0.45 mmol/l RBC, p < 0.01). The Na+ content was lower at 1 and 2 h (14.0 +/- 1.8; 13.8 +/- 1.2 versus baseline 15.7 +/- 1.2 mmol/100 g Hb, p < 0.05), but later it became normal. Plasma monovalent cationic levels and intracellular K+ content did not alter during the experiment. Our results indicate that the deterioration of enzyme activity occurs within the same time-frame that previously described morphological alterations in brain tissue develop, so the RBC Na+/K+-ATPase activity might reflect the progress of posthypoxial brain damage.
Vásárhelyi
B
B
First Department of Pediatrics, Semmelweis Medical University, Budapest, Hungary. barna@heim.sote.hu
Dobos
M
M
Temesvári
P
P
Abrahám
C
C
Pintér
S
S
Tulassay
T
T
D000255:Adenosine Triphosphate / Q000097:blood; D000818:Animals; D000831:Animals, Newborn / Q000097:blood*; D001238:Asphyxia Neonatorum / Q000150:complications / Q000201:enzymology* / Q000628:therapy; D001927:Brain Diseases / Q000201:enzymology / Q000209:etiology; D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D008297:Male; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D013552:Swine
D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D010100:Oxygen