Pyruvate-enriched cardioplegia suppresses cardiopulmonary bypass-induced myocardial inflammation.
BACKGROUND
Cardiopulmonary bypass-induced oxidative stress initiates inflammation that can damage the myocardium. This study tested whether cardioplegia enriched with the intermediary metabolite and antioxidant pyruvate dampens postbypass myocardial inflammation.


METHODS
Pigs were maintained on cardiopulmonary bypass while their hearts were arrested for 60 minutes with 4:1 blood:crystalloid cardioplegia, in which the crystalloid contained 188 mM glucose ± 24 mM pyruvate. Pigs were weaned from bypass after 30 minutes of whole blood reperfusion and recovered for 4 hours. Glutathione (GSH) and glutathione disulfide (GSSG) were measured in coronary sinus plasma to indirectly monitor myocardial GSH redox state (GSH/GSSG). Left ventricular myocardium was sampled 4 hours after cardiopulmonary bypass for analyses of C-reactive protein, matrix metalloproteinases 2 and 9 and tissue inhibitor of metalloproteinase-2 (TIMP-2), and to assess neutrophil infiltration by histology and myeloperoxidase assay.


RESULTS
Coronary sinus GSH/GSSG fell 70% after cardiopulmonary bypass with control cardioplegia, but pyruvate cardioplegia produced a robust increase in coronary sinus GSH/GSSG that persisted for 4 hours after bypass. Myocardial C-reactive protein content increased 5.6-fold after control bypass, and neutrophil infiltration and myeloperoxidase activity also increased, but pyruvate-fortified cardioplegia prevented these inflammatory effects. Control cardioplegia lowered myocardial TIMP-2 content by 59% and increased matrix metalloproteinase-9 activity by 35% versus nonbypass sham values, but pyruvate cardioplegia increased TIMP-2 content ninefold versus control cardioplegia and prevented the increase in matrix metalloproteinase-9. Matrix metalloproteinase-2 was not affected by bypass ± pyruvate.


CONCLUSIONS
Pyruvate-enriched cardioplegia dampens cardiopulmonary bypass-induced myocardial inflammation. Increased GSH/GSSG and TIMP-2 may mediate pyruvate's effects.
Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA.
Myoung-Gwi
MG
Ryou
Devin C
DC
Flaherty
Besim
B
Hoxha
Hunaid
H
Gurji
Jie
J
Sun
Lisa M
LM
Hodge
Albert H
AH
Olivencia-Yurvati
Robert T
RT
Mallet
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002097:C-Reactive Protein / Q000032:analysis; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D005260:Female; D005978:Glutathione / Q000097:blood; D019803:Glutathione Disulfide / Q000097:blood; D006324:Heart Arrest, Induced; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000032:analysis; D020780:Matrix Metalloproteinase 9 / Q000032:analysis; D009205:Myocarditis / Q000209:etiology / Q000517:prevention & control*; D009206:Myocardium / Q000473:pathology; D020556:Neutrophil Infiltration; D019289:Pyruvic Acid / Q000494:pharmacology*; D013552:Swine; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000032:analysis
D000975:Antioxidants; D019716:Tissue Inhibitor of Metalloproteinase-2; D019289:Pyruvic Acid; D002097:C-Reactive Protein; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D005978:Glutathione; D019803:Glutathione Disulfide