Red blood cell energy metabolism during cardiopulmonary bypass.
BACKGROUND
During cardiopulmonary bypass (CPB) an intracellular ATP deficit could theoretically play a role in changes of erythrocyte shape and deformability caused by mechanical trauma. We therefore studied erythrocyte energy metabolism in 12 patients undergoing normothermic CPB for myocardial revascularization.


METHODS
Blood samples were collected prior to and 45 minutes after CPB beginning and analyzed for erythrocyte ATP, ADP, and AMP and their metabolites, erythrocyte NAD and NADP, plasma and whole blood lactate (Lact(p) and Lact(b) respectively), and whole blood pyruvate (Pyr(b)).


RESULTS
Values were expressed as mean +/- standard deviation or median (lower and higher quartiles) on the ground of a test for normality. During CPB erythrocyte nucleotides and their metabolites did not change significantly (ATP: 60.2+/-12.1 vs. 68.3+/-13.0; ADP: 12.2+/-3.6 vs. 12.0+/-3.1; AMP: 0.43+/-24 vs. 0.44+/-0.26; adenosine: 0.063 (0.034-0.203) vs. 0.77 (0.032-0.221); inosine: 0.064 (0.023-0.072) vs. 0.075 (0.025-0.111); hypoxanthine: 0.330+/-0.272 vs. 0.367+/-0.223; xanthine: 0.193+/-0.090 vs. 0.220+/-0.095; NAD: 3.149+/-0.743 vs. 3.358+/-0.851; values in microM/mM packed red blood cell hemoglobin) while NADP increased (2.110+/-0.390 vs. 2.433+/-0.288 microM/mM packed red blood cell hemoglobin; p<0.05). Ringer lactate, with which the extracorporeal circuit was primed, caused Lact(p) to increase (1.87+/-0.81 vs. 3.27+/-1.15 mM/l; p<0.01). Some lactate entered erythrocytes since Lact(p)/Lact(b) ratio did not change (1.09+/-0.25 vs. 1.07+/-0.23) and some was transformed into pyruvate since Pyr(b) increased [62.9 (30.3-73.3) vs. 100.5 (61.0-146.9) microM/l; p<0.01]. Lact(b)/Pyr(b) ratio did not change significantly [22.6 (16.1-40.5) vs. 27.9 (17.5-35.2)] so that NAD/NADH ratio and, consequently, the rate of glycolysis were unlikely to change too.


CONCLUSIONS
Erythrocyte energy metabolism is not affected by CPB, at least during the period of time taken into account in this study.
Cavaliere
F
F
Department of Anesthesiology and Resuscitation, Catholic University of the Sacred Heart, Rome, Italy.
Meo
F
F
Scapigliati
A
A
Sciarra
M
M
Schiavello
R
R
D000227:Adenine Nucleotides / Q000378:metabolism*; D000368:Aged; D001831:Body Temperature; D002315:Cardiopulmonary Bypass; D002851:Chromatography, High Pressure Liquid; D001026:Coronary Artery Bypass / Q000379:methods; D003327:Coronary Disease / Q000097:blood / Q000601:surgery; D004734:Energy Metabolism; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019289:Pyruvic Acid / Q000378:metabolism
D000227:Adenine Nucleotides; D006454:Hemoglobins; D019344:Lactic Acid; D019289:Pyruvic Acid