Oxidative stress produced by circulating microparticles in on-pump but not in off-pump coronary surgery.
OBJECTIVE
This study was undertaken to assess whether plasmas isolated during off-pump coronary surgery trigger less oxidative stress than those isolated during on-pump surgery.


RESULTS
Plasmas were sampled from patients before (TO), just after (TI) and 24 hours after (T2) cardiac surgery (n=24 on-pump and n=10 off-pump). Rings of rat thoracic aortas were incubated for 20 hours with these different plasmas (100 microl + 4 ml medium) or saline (control). Thereafter, superoxide anion production was assessed by chemiluminescence and the mean signal was expressed as percent of that in the control ring. In rat aorta exposed to plasmas from on-pump CABG patients (n=6), the signal was enhanced by 210 +/- 29% at T1 (P < 0.05) and by 174 +/- 29% at T2 (P < 0.05) versus 53 +/- 12% at T0. Moreover, at T1 and T2, there was an upregulation of p22(phox), the key subunit of NADPH oxidase, the main enzyme involved in oxidative stress of the vascular wall. In contrast, off-pump plasmas did not induce this superoxide production. Incubation with microparticles obtained by ultracentrifugation also markedly enhanced the signal at T1 and T2 (vs. T0) in the on-pump group (but not in the off-pump group). Selective removal of CD34, CD105, CD59, CD146, CD42 microparticles using flow cytometry did not abolish the signal. CRP and SAA plasma levels were enhanced only at T2 in both groups.


CONCLUSIONS
Plasmas isolated after on-pump but not off-pump coronary bypass surgery can induce superoxide generation by the vascular wall which seems related to circulating microparticles remaining present at least 24 hours after the procedure that might be of endothelial origin.
Laboratory of Physiology & Pharmacology, Institute of Pharmacy, Belgium.
David
D
Fontaine
Olivier
O
Pradier
Mirjam
M
Hacquebard
Constantin
C
Stefanidis
Yvon
Y
Carpentier
Didier
D
de Canniere
Jeanine
J
Fontaine
Guy
G
Berkenboom
D000368:Aged; D000818:Animals; D001013:Aorta, Thoracic; D002097:C-Reactive Protein / Q000032:analysis; D055252:Cell-Derived Microparticles / Q000502:physiology*; D001026:Coronary Artery Bypass; D047549:Coronary Artery Bypass, Off-Pump; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D049449:Luminescence; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D000685:Serum Amyloid A Protein / Q000032:analysis; D013482:Superoxide Dismutase / Q000097:blood
D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein; D013482:Superoxide Dismutase