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Background: Glucocorticoids can reduce myocardial dysfunction associated with ischemia and reperfusion injury following cardiopulmonary bypass (CPB) and circulatory arrest. The hypothesis was that maintenance of cardiac function after CPB with methylprednisolone therapy results, in part, from preservation of myocyte calcium cycling., Methods: Piglets (5-7 kg) underwent CPB and 120 min of hypothermic circulatory arrest with (CPB-GC) or without (CPB) methylprednisolone (30 mgkg(-1)) administered 6h before and at CPB. Controls (No-CPB) did not undergo CPB or receive glucocorticoids (n=6 per treatment). Myocardial function was monitored in vivo for 120 min after CPB. Calcium cycling was analyzed using rapid line-scan confocal microscopy in isolated, fluo-3-AM-loaded cardiac myocytes. Phospholamban phosphorylation and sarco(endo)plasmic reticulum calcium-ATPase (SERCA2a) protein levels were determined by immunoblotting of myocardium collected 120 min after CPB. Calpain activation in myocardium was measured by fluorometric assay., Results: Preload recruitable stroke work in vivo 120 min after reperfusion decreased from baseline in CPB (47.4±12 versus 26.4±8.3 slope of the regression line, P<0.05), but was not different in CPB-GC (41±8.1 versus 37.6±2.2, P=0.7). In myocytes isolated from piglets, total calcium transient time remained unaltered in CPB-GC (368±52.5 ms) compared with controls (434.5±35.3 ms; P=0.07), but was prolonged in CPB myocytes (632±83.4 ms; P<0.01). Calcium transient amplitude was blunted in myocytes from CPB (757±168 nM) compared with controls (1127±126 nM, P<0.05) but was maintained in CPB-GC (1021±155 nM, P>0.05). Activation of calpain after CPB was reduced with glucocorticoids. Phospholamban phosphorylation and SERCA2a protein levels in myocardium were decreased in CPB compared with No-CPB and CPB-GC (P<0.05)., Conclusions: The glucocorticoid-mediated improvement in myocardial function after CPB might be due, in part, to prevention of calpain activation and maintenance of cardiac myocyte calcium cycling., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: Cardiac dysfunction after brain death (BD) limits donors for cardiac transplantation. Glucocorticoids ameliorate brain death-induced donor heart dysfunction. We hypothesized that glucocorticoid therapy alleviates myocardial depression through altering the balance between pro- and anti-inflammatory mediators via the nuclear factor-kappaB (NF-kappaB)/inhibitor of kappaB-alpha (IkappaBalpha) pathway and/or by preserving beta-adrenergic receptor (betaAR) signaling in the heart., Methods: Crossbred pigs (25 to 35 kg) were randomly assigned to the following groups (n = 5/treatment): sham (Group 1); BD (Group 2); and BD with glucocorticoids (30 mg/kg methylprednisolone), either 2 hours before (Group 3) or 1 hour after BD (Group 4). Tumor necrosis factor-alpha (TNF-alpha) levels were measured in plasma at baseline and 1 hour and 6 hours after BD. Protein levels were measured in left ventricular homogenates procured 6 hours after BD., Results: Pro-inflammatory proteins (TNF-alpha) and interleukin-6 were lower in Group 3 and Group 4 compared with Group 2 at 6 hours after BD (p < 0.01). Intracellular adhesion molecule-1 was also lower in Group 4 compared with Group 2 (p = 0.001). Interleukin-10, an anti-inflammatory mediator, was lower in Group 4 than in Group 2 (p < 0.001), but not different between Groups 2 and 3. At 6 hours after BD, neither NF-kappaB activity nor basal adenylate cyclase activity differed between Groups 3 and 4 compared with Group 2., Conclusions: Glucocorticoids maintained myocardial function and shifted the balance of pro- and anti-inflammatory mediators after BD. The mechanisms by which glucocorticoids preserve myocardial function, however, do not appear to involve the NF-kappaB pathway or betaAR signaling.

Background: Traumatic brain injury and subsequent brain death (BD) account for nearly half of all organ donors, yet only 33% of available hearts are transplanted. Alterations in multiple physiologic pathways after BD can lead to cardiac dysfunction and exclusion from transplantation. Triple hormone resuscitation with methylprednisolone, thyroid hormone and vasopressin has had inconsistent results in the effort to reduce cardiac dysfunction associated with BD, but individual analysis of these agents is limited. The hypothesis was that glucocorticoid administration alone could reduce BD-associated cardiac dysfunction., Methods: Crossbred pigs (25 to 35 kg) had BD induced by sub-dural balloon inflation. Hemodynamics were measured for 360 minutes after BD. Negative cerebral perfusion pressures and decreased laser Doppler cerebral blood flow confirmed BD. Animals (n = 5/treatment group) received: saline (Group 1); 30 mg/kg methylprednisolone 2 hours before BD (Group 2); or 30 mg/kg methylprednisolone 1 hour after BD (Group 3). Repeated measures analysis of variance and unpaired t-tests were used for appropriate comparisons., Results: Left ventricular (LV) pre-load recruitable stroke work (PRSW) decreased in untreated Group 1 over time (p < 0.001), whereas PRSW in animals treated with glucocorticoids, Groups 2 and 3, was not different from baseline at 360 minutes after BD. Diastolic function measured as LV -dP/dt (minimum derivative of the change in pressure over time) and tau (time constant of isovolumic relaxation) was also preserved 360 minutes after brain death by glucocorticoids in Groups 2 and 3 (p > 0.05). Oxygen delivery 360 minutes after BD was higher in Group 2 compared with Group 1 (p = 0.02) and Group 3 (p = 0.006)., Conclusions: Glucocorticoid therapy before or after BD preserved LV systolic and diastolic function. Glucocorticoids administered after brain death might increase the number of hearts available for transplant by reducing brain death-associated cardiac dysfunction.

Background: Glucocorticoids during cardiopulmonary bypass benefit pediatric patients undergoing repair of congenital heart defects and are routine therapy, but underlying mechanisms have not been fully examined. The hypothesis was that glucocorticoids could improve cardiopulmonary recovery after cardiopulmonary bypass and deep hypothermic circulatory arrest., Methods: Crossbred piglets (5 to 7 kg) were cooled with cardiopulmonary bypass, followed by 120-min deep hypothermic circulatory arrest. Animals were then warmed to 38 degrees C, removed from bypass, and maintained for 120 min. Methylprednisolone (60 mg/kg) was administered in the cardiopulmonary bypass pump prime (intraoperative glucocorticoids) or 6 hours before bypass (30 mg/kg) in addition to the intraoperative dose (30 mg/kg; preoperative and intraoperative glucocorticoids). Controls (no glucocorticoids) received saline., Results: Pulmonary vascular resistance in controls increased from a baseline of 152 +/- 40 to 364 +/- 29 dynes. s/cm(5) at 2 hours of recovery (p < 0.001). Intraoperative glucocorticoids did not alleviate the increase in pulmonary vascular resistance (301 +/- 55 dynes. s/cm(5) at 2 hours of recovery, p < 0.001). However, animals receiving pre and intraoperative glucocorticoids had no increase in pulmonary vascular resistance (155 +/- 54 dynes. s/cm(5)). Plasma endothelin-1 in controls increased from 1.3 +/- 0.2 at baseline to 9.9 +/- 2.0 pg/mL at 2 hours recovery (p < 0.01), whereas glucocorticoid-treated animals had lower endothelin-1 levels (4.5 +/- 2.1 pg/ml, preoperative and intraoperative glucocorticoids; 4.9 +/- 1.7 pg/mL, intraoperative glucocorticoids) at the end of recovery (p < 0.05). Intracellular adhesion molecule-1 in lung tissue was lower in animals receiving pre and intraoperative glucocorticoids (p < 0.05). Myeloperoxidase activity was elevated in control lungs at 2 hours of recovery compared with glucocorticoid-treated groups (p < 0.05). Inhibitor kappaBalpha, the inhibitor of nuclear factor-kappaB, was higher in lungs of animals receiving glucocorticoids compared with controls (p < 0.05)., Conclusions: Glucocorticoids prevented pulmonary hypertension after cardiopulmonary bypass and deep hypothermic circulatory arrest, which was associated with reduced plasma endothelin-1. Glucocorticoids also reduced pulmonary intercellular adhesion molecule-1 and myeloperoxidase activity. Inhibition of nuclear factor-kappaB, along with reduced neutrophil activation, contributed to glucocorticoid alleviation of pulmonary hypertension after cardiopulmonary bypass and deep hypothermic circulatory arrest.

Objective: The hypotheses were that glucocorticoid administration could improve ventricular recovery by reducing cardiopulmonary bypass (CPB)-induced inflammatory response and that presurgical administration might be more effective than intraoperative dosing., Design: Animal case study., Subjects: Crossbred piglets (5-7 kg)., Interventions: Piglets were cooled with CPB, followed by 120 mins of deep hypothermic circulatory arrest (DHCA). Animals were rewarmed to 38 degrees C, removed from CPB, and maintained for 120 mins. Methylprednisolone (60 mg/kg) was administered in the CPB pump prime (intraoperative glucocorticoid [intraop GC]) or 6 hrs before CPB (30 mg/kg) in addition to the intraoperative dose (30 mg/kg; pre- and intraop GC). Controls (no GC) received saline., Measurements and Main Results: In no GC, left ventricle (LV) positive change in pressure in time (+dP/dt) (mm Hg/sec) had a mean +/- SD of 1555 +/- 194 at baseline vs. 958 +/- 463 at 120 mins after CPB, p=.01). LV +dP/dt was maintained in glucocorticoid-treated animals (1262 +/- 229 at baseline vs. 1212 +/- 386 in intraop GC and 1471 +/- 118 vs. 1393 +/- 374 in pre-intraop GC). Glucocorticoids reduced myocardial interleukin-6 messenger RNA expression, measured by ribonuclease protection assay, at 120 mins after CPB compared with animals receiving saline (p<.05), although interleukin-6 plasma and LV protein concentrations were not affected. Interleukin-10 myocardial protein concentrations were elevated after CPB-DHCA with higher concentrations in glucocorticoid-treated animals (p<.05). Glucocorticoid treatment maintained myocardial concentrations of the inhibitor of nuclear factor-kappaB in the cytosol and decreased nuclear factor-kappaB concentrations detected in the nucleus in a DNA/protein interaction array., Conclusions: Glucocorticoids improved recovery of LV systolic function in neonatal animals undergoing CPB-DHCA. Animals receiving glucocorticoids before CPB had better postoperative oxygen delivery than those receiving only intraoperative treatment. Maintenance of cardiac function after glucocorticoids might be due, in part, to alterations in the balance of pro- and anti-inflammatory proteins, possibly through nuclear factor-kappaB-dependent pathways.

Degradation of troponin I (TnI) by calpain occurs with myocardial stunning in ischemia-reperfusion injury. Glucocorticoids attenuate myocardial ischemia-reperfusion injury, but their effect on TnI degradation is unknown. A piglet model was used to test the hypotheses that cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) are associated with TnI degradation and that TnI alterations could be prevented by glucocorticoid treatment. Piglets were cooled to 18 degrees C, subjected to 2 h of circulatory arrest, rewarmed to 37 degrees C, and allowed to recover for 2 h. Methylprednisolone was administered 6 h before surgery (3 0 mg/kg) and at initiation of CPB (30 mg/kg). The untreated group received saline. Left ventricular tissue was collected after recovery and analyzed by Western blot for TnI, calpain, and calpastatin (the natural inhibitor of calpain). CPB/DHCA animals had 27.4 +/- 0.2% of total detected TnI present in degraded form. Glucocorticoid treatment significantly decreased the percentage of degraded TnI (12.0 +/- 0.1%, p < 0.05). Calpain I and calpain II increased after CPB/DHCA compared with non-CPB/DHCA controls (p < 0.05), with or without glucocorticoid treatment. Calpastatin significantly decreased in untreated CPB/DHCA animals compared with non-CPB/DHCA controls (p < 0.05), but levels were preserved by glucocorticoids. Glucocorticoids were associated with preservation of maximum rate of increase of left ventricular pressure at 95 +/- 10% of baseline, whereas maximum rate of increase of left ventricular pressure decreased to 62 +/- 12% of baseline without steroids. TnI degradation occurs after CPB/DHCA in neonatal pigs. Reduction in reperfusion injury by glucocorticoids may depend partly on preservation of calpastatin activity and intact TnI.

Background: Transient myocardial dysfunction often occurs after ischemia-reperfusion with immature myocardium appearing particularly susceptible. Neutrophil adhesion and activation contribute to ischemia-reperfusion injury after cardiopulmonary bypass (CPB), possibly resulting in cell death. The hypothesis was that glucocorticoids could prevent reperfusion-induced myocardial dysfunction by blunting leukocyte-mediated injury., Methods: Neonatal piglets were cooled with CPB followed by 2 hours of circulatory arrest. Animals were rewarmed, removed from CPB, and allowed to recover for 2 hours. Methylprednisolone (60 mg/kg) was administered in the CPB priming solution to one group (intraoperative glucocorticoids). In another group (preoperative glucocorticoids), 30 mg/kg methylprednisolone was administered 6 hours before CPB in addition to the intraoperative dose (30 mg/kg). Control animals received no glucocorticoids., Results: Apoptotic myocardial cells measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay and caspase-3 activity were reduced in animals administered glucocorticoids compared with controls (p < 0.05). Animals receiving either intraoperative or preoperative glucocorticoids had 0.10 +/- 0.07 and 0.13 +/- 0.05 apoptotic cells per high-power field, respectively, whereas 0.33 +/- 0.15 apoptotic cells were detected with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling in control animals. Glucocorticoid administration reduced myocardial intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 mRNA expression compared with control piglets. Maximum rate of increase of left ventricular pressure was 62% +/- 9% of baseline in control animals at 120 minutes of recovery compared with 96% +/- 6% and 95% +/- 10% of baseline in animals receiving intraoperative and preoperative glucocorticoids, respectively (p < 0.05)., Conclusions: The reduction of neutrophil adhesion and activation proteins in neonatal myocardium was associated with less apoptotic cell death after glucocorticoid administration. The blunting of apoptosis in glucocorticoid-treated animals was also associated with improved recovery of left ventricular systolic function in neonatal animals after CPB and circulatory arrest. Glucocorticoid attenuation of myocardial apoptosis might have important implications for maintaining long-term ventricular function after ischemia and reperfusion.