ABSTRACT
AbstractObjective:The aim of this prospective study was to assess the dynamics of oxidative stress during coronary artery bypass surgery with cardiopulmonary bypass.Methods:Sixteen patients undergoing coronary artery bypass grafting were enrolled. Blood samples were collected from the systemic circulation during anesthesia induction (radial artery - A1), the systemic venous return (B1 and B2) four minutes after removal of the aortic cross-clamping, of the coronary sinus (CS1 and CS2) four minutes after removal of the aortic cross-clamping and the systemic circulation four minutes after completion of cardiopulmonary bypass (radial artery - A2). The marker of oxidative stress, malondialdehyde, was measured using spectrophotometry.Results:The mean values of malondialdehyde were (ng/dl): A1 (265.1), B1 (490.0), CS1 (527.0), B2 (599.6), CS2 (685.0) and A2 (527.2). Comparisons between A1/B1, A1/CS1, A1/B2, A1/CS2, A1/A2 were significant, with ascending values (P<0.05). Comparisons between the measurements of the coronary sinus and venous reservoir after the two moments of reperfusion (B1/B2 and CS1/CS2) were higher when CS2 (P<0.05). Despite higher values after the end of cardiopulmonary bypass (A2), when compared to samples of anesthesia (A1), those show a downward trend when compared to the samples of the second moment of reperfusion (CS2) (P<0.05).Conclusion:The measurement of malondialdehyde shows that coronary artery bypass grafting with cardiopulmonary bypass is accompanied by increase of free radicals and this trend gradually decreases after its completion. Aortic clamping exacerbates oxidative stress but has sharper decline after reperfusion when compared to systemic metabolism. The behavior of thiobarbituric acid species indicates that oxidative stress is an inevitable pathophysiological component.
ResumoObjetivo:O objetivo deste estudo prospectivo foi avaliar a dinâmica do estresse oxidativo durante a cirurgia de revascularização miocárdica com circulação extracorpórea.Métodos:Participaram 16 pacientes submetidos à revascularização miocárdica. As amostras de sangue foram coletadas da circulação sistêmica, no momento da indução anestésica (artéria radial - A1), do retorno venoso sistêmico (B1 e B2), quatro minutos após a remoção do pinçamento aórtico, do seio coronariano (SC1 e SC2), quatro minutos após a remoção do pinçamento aórtico, e da circulação sistêmica, quatro minutos após finalização da circulação extracorpórea (artéria radial - A2). O marcador do estresse oxidativo, malondialdeído, foi dosado utilizando espectrofotometria.Resultados:Os valores médios de malondialdeído foram (ng/dl): A1 (265,1), B1 (490,0), SC1 (527,0), B2 (599,6), SC2 (685,0) e A2 (527,2). As comparações entre A1/B1, A1/SC1, A1/B2, A1/SC2, A1/A2 foram significativas, com valores ascendentes (P<0,05). As comparações entre as dosagens do seio coronário e reservatório venoso após os dois momentos de reperfusão (B1/SC1 e B2/SC2) foram mais elevadas no momento SC2 (P<0,05). Apesar dos valores mais elevados após o término da circulação extracorpórea (A2), quando comparadas às amostras da indução anestésica (A1), aqueles apresentam tendência de queda quando comparadas as amostras do segundo momento de reperfusão (SC2) (P<0,05).Conclusão:As dosagens de malondialdeído mostram que a revascularização miocárdica com circulação extracorpórea é acompanhada de aumento de radicais livres com tendência deste diminuir progressivamente após seu término. O pinçamento aórtico exacerba o estresse oxidativo, porém apresenta queda mais acentuada após a reperfusão quando comparadas ao do metabolismo sistêmico. O comportamento das espécies reativas ao ácido tiobarbitúrico indica que o estresse oxidativo é um componente patofisiológico inevitável.
Subject(s)
Female , Humans , Male , Cardiopulmonary Bypass/adverse effects , Coronary Artery Bypass/adverse effects , Lipid Peroxidation/physiology , Malondialdehyde/blood , Oxidative Stress/physiology , Biomarkers/blood , Coronary Sinus/physiology , Perioperative Period , Prospective Studies , Radial Artery/chemistry , Spectrophotometry , Statistics, Nonparametric , Time Factors , Thiobarbituric Acid Reactive Substances/analysisABSTRACT
OBJECTIVES: The biological functions of transforming growth factor-β signaling that involves Smad proteins have not been previously investigated with respect to coronary artery bypass grafts. The aim of the present study was to observe the immunostaining of proteins that are related to this signaling pathway. METHODS: Fifteen remnants of coronary artery bypass grafts, including nine saphenous veins, three radial arteries and three mammary arteries, were collected from 12 patients who were undergoing coronary artery bypass. Hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining of transforming growth factor-β1, type I receptor of transforming growth factor-β, Smad2/3, Smad4, and Smad7 were performed. RESULTS: The saphenous veins showed more severe intimal degeneration, more severe smooth muscle cell proliferation and more collagen deposition than the arterial grafts, as evidenced by hematoxylin and eosin and Masson's trichrome stainings. Immunohistochemical assays demonstrated that the majority of the transforming growth factor-β1 signaling cytokines were primarily localized in the cytoplasm in the medial layers of all three types of grafts, whereas ectopic transforming growth factor-β1, type I receptor of transforming growth factor-β, and Smad7 overexpressions in the interstices were observed particularly in the saphenous vein and radial arterial grafts. CONCLUSION: Enhanced transforming growth factor-β1 signal transduction with medial smooth muscle cell proliferation and ectopic transforming growth factor-β1, the presence of the type I receptor of transforming growth factor-β, and Smad7 overexpressions in the extracellular matrix may provide primary evidence for early or late graft failure.