Indices of Apoptosis Activation After Blood Cardioplegia and Cardiopulmonary Bypass

Abstract

Background— Cardioplegic arrest (CA) using cold blood cardioplegia (CBC) has been reported to reduce ischemia-reperfusion (IR)-induced myocardial injury via apoptosis. We studied key apoptotic mediators via the caspase-dependent and intrinsic pathways as well as poly(ADP)-ribosylating protein (PARP) activity in myocardial and peripheral tissues after CA and cardiopulmonary bypass (CBP). Methods and Results— Right atrial (RA) and skeletal muscle(SM) was harvested from cardiac surgical patients with similar baseline characteristics (N =6) before and after CPB and CBC. Total and modified caspase-3, Bcl-2, Bad, apoptosis-inducing factor (AIF), and PARP were quantified by immunoblotting. Terminal caspase-3 activity was assessed and immunohistochemistry was performed for PARP and AIF. TUNEL staining was used for identification of apoptotic cells. Microarray gene expression analysis was performed using Affymetrix U95 GeneChip. In RA tissue, CA with CBC significantly increased phosphorylation of Bcl-2 (Ser 70 ), Bad (Ser 112 ) (2.63±0.4 and 1.77±0.3-fold respectively; P <0.05), and cleavage of the downstream caspase 3 (1.45±0.1-fold; P <0.05). There was no significant change in total protein levels. Also, there was an increase in mature AIF (57 kDa) levels (1.22±0.01-fold; P <0.05) and a trend toward nuclear translocation on histological staining. Caspase 3 activity was increased 1.5±0.14-fold ( P <0.05). The number of apoptotic cells in atrial tissue increased after compared with before CPB/CA using TUNEL staining (1.55±0.66 versus 0.325±0.05%, respectively; P =0.03). In contrast, SM samples did not show any of the changes observed in RA tissue after CPB. Conclusion— Despite optimal current surgical myocardial protection, we found that CA with CBC induced both programmed cell death and survival signaling in myocardial tissue.

Off-pump coronary artery bypass surgery is associated with fewer gene expression changes in the human myocardium in comparison with on-pump surgery

“…The main finding of the study is that off-pump surgery is associated with fewer alterations in gene expression linked to inflammation and apoptosis. This work completes earlier studies (3,10,11,13,14,16,23) that have focused on on-pump surgery with CPB and ischemia-CA.…”

“…Recent studies have used microarray technology to examine the human myocardial stress response during cardiac surgery (3,10,11,14,16,23). Ruel et al (16) used a 12,625 gene array to examine the cardiac and peripheral gene expression responses to CPB and CA in human atrial myocardium and skeletal muscle.…”

Impact of N-Acetylcysteine on Neonatal Cardiomyocyte Ischemia-Reperfusion Injury

“…Myocardial IR injury leads to oxygen-derived free radical production, membrane lipid peroxidation, and impaired postbypass contractility (20,21). Elevated oxygen-derived free radical production initiates and/or promotes apoptotic cascades leading to cell death and tissue damage (22). In this study, we showed that NAC, a potent antioxidant, attenuates NADPH oxidase-mediated ROS production and caspase-3 expression, decreases the percentage of phox and caspase-3 in neonatal rabbit hearts.…”

Protective effect of cardioplegia with poly (ADP-ribose) polymerase-1 inhibitor against myocardial ischemia-reperfusion injury: in vitro study of isolated rat heart model

“…Recently, several studies provided the evidence that the myocardial apoptosis is involved in the pathogenesis of persistent myocardial dysfunction after cardiac surgery 1 . Several mediators of apoptosis, including apoptosis-inducing factor (AIF) and cytochrome c, were activated after 10 to 20 min of cardiopulmonary bypass 17 . It had been proposed that PARP is implicated in various types of cell death by following mechanisms: (a) PARP could deplete NAD + and ATP of cells, resulting in an energy crisis; (b) PARP serves as a main substrates for caspases; and (c) PARP activation signals AIF release from mitochondria, resulting in a caspase-independent pathway of programmed cell death 6,18 .…”