Backtable heat-enhanced preconditioning: a simple and effective means of improving function of heart transplants.

BACKGROUND: Cardiac harvest teams are usually committed to immediately transfer the explanted donor heart into its cold storage solution. We tested the opposite hypothesis that a brief prestorage episode of heat-enhanced ischemic preconditioning could be protective. METHODS: Fifty-three isolated isovolumic rat hearts underwent 4 hours of cold (4 degrees C) storage in the Celsior preservation solution and 2 hours of reperfusion. Control hearts were immediately immersed after arrest. In the 3 treated groups, 2 customized thermal probes were first applied onto the left ventricular free wall of the explanted heart at 22 degrees C, 37 degrees C or 42.5 degrees C for 15 minutes before immersion. Each of the selected temperatures were monitored at the probe-tissue interface by a thermocouple. RESULTS: Whereas base line end-diastolic pressure was set at = 8 mm Hg in all groups, it increased during reperfusion (mean +/- SEM) to 28+/-3, 27+/-3, 17+/-1, and 18+/-2 mm Hg in control, 22 degrees C, 37 degrees C and 42.5 degrees C-heated hearts, respectively (37 degrees C and 42.5 degrees C: p < 0.05 versus controls and 22 degrees C). Slopes of pressure-volume curves featured similar patterns. Likewise, reperfusion dP/dT (mm Hg/s(-1)) was significantly lower in control and 22 degrees C hearts (1,119+/-114 and 1,076+/-125, respectively) than in those undergoing prestorage heating to 37 degrees C and 42.5 degrees C (1,545+/-109 and 1,719+/-111, p < 0.05 and p < 0.01 versus controls and 22 degrees C, respectively). Western blot analysis of LV samples did not demonstrate any upregulation of HSP 72 in either group. Conversely, the involvement of preconditioning was evidenced by the loss of protection in the 42.5 degrees C-heated hearts when, in 2 additional groups, the storage solution was supplemented with either the protein kinase C and tyrosine kinase inhibitors chelerythrine (5 micromol/L) and genistein (50 micromol/L) or the mitochondrial K(ATP) channel inhibitor 5-hydroxydecanoate (200 micromol/L). CONCLUSIONS: A brief period of postexplant ischemia with enhancement by topical heating ("backtable preconditioning") could be a simple and effective means of improving the functional recovery of heart transplants.

Ischemic preconditioning with opening of mitochondrial adenosine triphosphate-sensitive potassium channels or Na/H exchange inhibition: which is the best protective strategy for heart transplants?

OBJECTIVE: This study was designed to compare ischemic preconditioning with opening of mitochondrial adenosine triphosphate-sensitive potassium channels and Na(+)/H(+) exchange inhibition in an isolated heart model of cold storage, simulating the situation of cardiac allografts. METHODS: Sixty-seven isolated isovolumic buffer-perfused rat hearts were arrested with and stored in Celsior solution (Imtix-Sangstat) at 4 degrees C for 4 hours before a 2-hour reperfusion. Group I hearts served as controls and were arrested with and stored in Celsior solution. In group II, hearts were preconditioned by two 5-minute episodes of global ischemia, each separated by 5 minutes of reperfusion before arrest with Celsior solution. Group III hearts were arrested with and stored in Celsior solution supplemented with 100 micromol/L of the mitochondrial adenosine triphosphate-sensitive potassium channel opener diazoxide. In group IV, hearts received an infusion of diazoxide (30 micromol/L) during the first 15 minutes of reperfusion. Group V hearts underwent a protocol combining both interventions used in groups III and IV. In group VI, hearts were arrested with and stored in Celsior solution supplemented with 1 micromol/L of the Na(+)/H(+) exchange inhibitor cariporide. Group VII hearts received an infusion of cariporide (1 micromol/L) during the first 15 minutes of reperfusion. In group VIII, hearts underwent a protocol combining both interventions used in groups VI and VII. Group IX hearts were ischemically preconditioned as in group II, and sustained Na(+)/H(+) exchange inhibition during both storage and early reperfusion was used as in group VIII. RESULTS: On the basis of comparisons of postischemic left ventricular contractility and diastolic function, coronary flow, total creatine kinase leakage, and myocardial water content, values indicative of improved protection were obtained by combining ischemic preconditioning with Na(+)/H(+) exchange inhibition by cariporide given during storage and initial reperfusion. The endothelium-dependent vasodilatory postischemic responses to 5-hydroxytryptamine or acetylcholine and endothelium-independent responses to papaverine were not affected by these interventions. CONCLUSIONS: These data suggest that cardioprotection conferred by the Na(+)/H(+) exchange inhibitor cariporide is additive to that of ischemic preconditioning and might effectively contribute to improve donor heart preservation during cardiac transplantation.

Cardiac functional improvement by a human Bcl-2 transgene in a mouse model of ischemia/reperfusion injury.

BACKGROUND: Apoptosis has been shown to contribute to myocardial reperfusion injury. It has been suggested that, in reducing the apoptotic component within the ischemic area at risk, Bcl-2 overexpression could lead to a ventricular function improvement. METHODS: Transgenic mice overexpressing the anti-apoptotic human Bcl-2 cDNA in heart were subjected to a 1-h left coronary artery occlusion followed by a 24-h reperfusion. At the end of the experiment, left ventricular function was assessed by two-dimensional echocardiography. After sacrifice, the area at risk (AR) and the infarct area (IA) were determined by Evans blue and triphenyltetrazolium chloride staining, respectively. The extent of apoptosis was assessed by the TUNEL method. Non-transgenic littermates served as controls. RESULTS: Baseline AR was not different between Bcl-2 transgenic mice and their wild-type littermates. In contrast, left ventricular ejection fraction was significantly improved in the transgenic mice line (61.25 +/- 4.0%) compared to non-transgenic littermates (43.2 +/- 5.0%, p < 0.01). This functional amelioration was correlated with a significant reduction of infarct size in transgenic animals (IA/AR 18.51 +/- 3.4% vs 50.83 +/- 8.4% in non-transgenic littermates). Finally, apoptotic nuclei were less numerous in transgenic mice than in controls as quantified by TUNEL analysis (8.1 +/- 2.2% vs 20.6 +/- 4.4%). CONCLUSIONS: Bcl-2 overexpression is effective in reducing myocardial reperfusion injury and improving heart function. This benefit correlates with a reduction of cardiomyocyte apoptosis. The apoptotic component of ischemia/reperfusion injury could therefore constitute a new therapeutic target in the acute phase of myocardial infarction.

Opening of mitochondrial potassium channels: a new target for graft preservation strategies?

BACKGROUND: This study was designed to assess the protective effects of the mitochondrial adenosine triphosphate-sensitive potassium channel (KATP) opener diazoxide as an additive to heart preservation solution. METHODS: Forty isolated isovolumic buffer-perfused rat hearts were divided into four groups. Groups I and III hearts were arrested with and cold-stored in Celsior solution for 4 hr and 10 hr, respectively. In Groups II and IV, hearts underwent a protocol similar to that used in Group I and III, respectively, except that Celsior was supplemented with 100 micromol/L of diazoxide. RESULTS: The protective effects of diazoxide were primarily manifest as a better preservation of diastolic function and a reduction of myocardial edema. The improvement of postischemic systolic function was observed only after prolonged exposure to diazoxide in Group IV, compared with Group III. The endothelium-dependent and endothelium-independent coronary flow postischemic responses were not affected by the supplementation of Celsior with diazoxide. CONCLUSIONS: Pharmacologic activation of mitochondrial KATP channels seems to be an effective means of improving preservation of cold-stored hearts, which is consistent with the presumed role of these channels as end effectors of the cardioprotective preconditioning pathway.

Different regulation of cardiac and renal corticosteroid receptors in aldosterone-salt treated rats: effect of hypertension and glucocorticoids.

This study analysed the regulation of cardiac mineraloreceptor (MR) and glucoreceptor (GR) in aldosterone-salt treatment (AST). AST causes hypertension, left ventricle (LV) hypertrophy and decreases plasma corticosterone level. Ribonuclease protection assay and Western blot analysis showed a rise of MR mRNA (1.5- and 1.4-fold at day 15 and 30, respectively) and protein levels (1.8- and 4.1-fold at day 30 and 60, respectively) in the LV, but not in either the right ventricle (RV) or in kidney of treated rats. Addition of MR antagonist spironolactone (20 mg/kg/day) for 30 days failed to prevent these changes but was able to reduce AST-induced cardiac fibrosis. Similar hypertension-induced MR upregulations were observed in the LV of AngII-hypertensive rats and of 12-week-old SHR when compared to 4-week-old prehypertensive SHR. AST also enhanced left ventricular GR mRNA (2.0- and 3.0-fold at day 7 and 15, respectively) and protein contents (2.0- and 1.7-fold at day 30 and 60, respectively). In contrast to MR, GR levels were also upregulated in both RV and kidney. Such an upregulation was equally observed at mRNA and protein levels in LV, RV and kidney after adrenalectomy (15 days) and was prevented in both tissues after glucocorticoid replacement (adrenalectomy + dexamethasone at 100 micro g/kg/day for 15 days). Therefore, MR level may be controlled by hemodynamical factors whereas that of GR depends upon glucocorticoids level.

Cardiac aldosterone production and ventricular remodeling.

An intracardiac production of aldosterone has been recently reported in rat. This production is increased both acutely and chronically by angiotensin II, observations suggesting that the heart contains a steroidogenic system that is regulated similarly to the adrenal one. Cardiac production of aldosterone is small compared with that of the adrenal, raising the question of its function in normal conditions. Moreover, the regulation of this synthesis in pathophysiologic states remains unknown. In an analysis of the effects of a one-month myocardial infarction (MI) on the cardiac steroidogenic system, it was observed that aldosterone-synthase mRNA and the aldosterone concentration were increased by 2- and 3.5-fold, respectively, in the noninfarcted part of the rat left ventricle. MI also induced a 1. 9-fold increase in the cardiac angiotensin II level. Losartan prevented these changes, and the MI-induced collagen deposition in noninfarcted area of the left ventricle was reduced by 1.6- and 2. 5-fold by both spironolactone and losartan treatments, respectively. Thus, these observations indicate that MI is associated with tissue-specific activation of myocardial aldosterone synthesis. This activation is mediated by cardiac angiotensin II via the angiotensin II type 1 (AT1) receptor, and the resultant increase of intracardiac aldosterone level may be involved in post-MI ventricular remodeling.

Preconditioning by mitochondrial ATP-sensitive potassium channel openers: An effective approach for improving the preservation of heart transplants.

BACKGROUND: Recent studies have implicated mitochondrial ATP-sensitive potassium (K(ATP)) channels in the cardioprotective effects of ischemic preconditioning. The present study used a model of prolonged cold heart storage to assess whether the mitochondrial K(ATP) opener diazoxide could reproduce the protection conferred by ischemic preconditioning. METHODS AND RESULTS: Fifty-four isolated rat hearts were arrested with and stored in Celsior at 4 degrees C for 10 hours before a 2-hour reperfusion. They were divided into 5 groups. Group 1 hearts served as controls. In group 2, hearts were preconditioned by two 5-minute episodes of global ischemia, each separated by 5 minutes of reperfusion before arrest. In group 3, hearts received a 15-minute infusion of the mitochondrial K(ATP) opener diazoxide (30 micromol/L) followed by 5 minutes of washout before arrest. In groups 4 and 5, hearts underwent a protocol similar to that used in groups 2 and 3, respectively, except that the preconditioning was preceded by a 10-minute infusion of the mitochondrial K(ATP) blocker 5-hydroxydecanoate (5-HD, 100 micromol/L). Both ischemic and diazoxide preconditioning provided a similar degree of cardioprotection demonstrated by a significantly better preservation of left ventricular compliance, reduced leakage of creatine kinase, and smaller degree of myocardial edema compared with control hearts. These beneficial effects were abolished by 5-HD pretreatment. Postischemic left ventricular contractility and endothelium-dependent coronary response to 5-hydroxytryptamine and acetylcholine were not different among groups. However, the endothelium-independent vasodilatory postischemic response to papaverine was better preserved after ischemic and diazoxide preconditioning than in the other groups. CONCLUSION: These data support the concept that the cardioprotective effects of ischemic preconditioning can be duplicated by a mitochondrial K(ATP) opener and suggest that activation of these channels could be an effective means of improving the preservation of globally ischemic cold-stored hearts, as occurs during cardiac transplantation.

[Role of cardiac aldosterone in post-infarction ventricular remodeling in rats]. / Rôle de l'aldostérone cardiaque dans le remodelage ventriculaire du postinfarctus chez le rat.

Synthesis of aldosterone (Aldo) and corticosterone (B) has been recently reported in rat heart. However, regulation of this synthesis in pathophysiological states remains unknown. Thus, this study aimed to analyze effects of a one-month myocardial infarction (MI) on cardiac steroidogenic system. Levels of terminal enzymes of B (11 beta-hydroxylase: 11 beta H) and aldo (Aldo-synthase: AS) synthesis were assayed by quantitative RT-PCR. Cardiac Aldo and B levels were assessed by celite colum chromatography and radioimmunoassay. MI raised AS mRNA levels by 2.0-fold (p < 0.05) but downregulated that of 11 beta H by 2.4 fold (p < 0.05) in the noninfarcted part of the left ventricle (LV). Cardiac steroids production followed a similar pattern of regulation. Aldo level was increased in MI (319 +/- 85 vs 87 +/- 11 pg/mg of protein in control, p < 0.05) whereas that of B fell (2,412 +/- 318 vs 4,624 +/- 857 pg/mg of protein in control, p < 0.05). MI also induced an 1.9-fold increase in cardiac Ang II level. Such cardiac regulations were prevented by Ang II-AT1 receptor antagonist losartan (8 mg/kg/day) treatment. The Aldo receptor antagonist spironolactone (20 mg/kg/day) had no effect. Plasma Aldo and B, and adrenal 11 beta H and AS mRNA levels were unchanged whatever the treatment. The MI-induced collagen deposition in noninfarcted area of the LV was reduced by both spironolactone and losartan treatments by 1.6- and 2.5-fold, respectively. These data indicate that MI is associated with tissue-specific activation of myocardial aldosterone synthesis. This activation is mediated by cardiac Ang II via AT1 receptor and the resultant increase of intracardiac aldosterone level may be involved in post-MI ventricular remodeling.

Protective effects of Celsior in lung transplantation.

BACKGROUND: Celsior is a new preservation solution for heart transplants that recently has been shown also to improve protection of pulmonary grafts. As these data were obtained in isolated lung preparations, we sought to perform further tests with an in vivo model of allogeneic lung transplantation. METHODS: The left lungs of 41 rats were either transplanted immediately after harvest (controls) or flushed with and cold stored in Celsior or the blood-based Wallwork solution for 5 or 12 hours. Lungs were then reperfused for 30 minutes, after which ligation of the contralateral pulmonary artery and bronchus made the recipient rat exclusively dependent on the transplanted lung. Assessment of preservation was made on functional (blood gases, pulmonary hemodynamics) and structural (dry-to-weight ratio, light microscopy, myeloperoxidase [MPO] content) end points. RESULTS: The protective effects of Celsior were primarily manifest, once the contralateral lung had been functionally excluded, as a better preservation of oxygen tensions in the 5-hour storage experiments (416 +/- 52 mm Hg vs 406 +/- 59 mm Hg in controls [p = NS] and vs 239 +/- 34 mm Hg in Wallwork [p < 0.05 vs the 2 other groups]) and a smaller increase in pulmonary vascular resistance in the 12-hour storage experiments (10.2 +/- 4.1 mm Hg/mL/minute vs 3.2 +/- 1.1 mm Hg/mL/minute in controls [p = NS] and vs 23.1 +/- 4.3 mm Hg/mL/minute in Wallwork [p < 0.02 vs Celsior, p < 0.002 vs controls]). Survival was also longer in the 12-hour preserved Celsior group. Other end points were not significantly different between the two preservative solutions. CONCLUSION: These data support the efficacy of Celsior as a flush-out and storage solution for pulmonary grafts. Given its previously documented ability to adequately preserve heart transplants, Celsior might provide a unified "solution" to thoracic organ preservation.

Activation of cardiac aldosterone production in rat myocardial infarction: effect of angiotensin II receptor blockade and role in cardiac fibrosis.

BACKGROUND: This study analyzed the regulation and the role of the cardiac steroidogenic system in myocardial infarction (MI). METHODS AND RESULTS: Seven days after MI, rats were randomized to untreated infarcted group or spironolactone- (20 and 80 mg x kg-1 x d-1), losartan- (8 mg x kg-1 x d-1), spironolactone plus losartan-, and L-NAME- (5 mg x kg-1 x d-1) treated infarcted groups for 25 days. Sham-operated rats served as controls. In the noninfarcted myocardium of the left ventricle (LV), MI raised aldosterone synthase mRNA (the terminal enzyme of aldosterone synthesis) by 2. 0-fold and the aldosterone level by 3.7-fold. Conversely, MI decreased 11beta-hydroxylase mRNA (the terminal enzyme of corticosterone synthesis) by 2.4-fold and the corticosterone level by 1.9-fold. MI also induced a 1.9-fold increase in cardiac angiotensin II level. Such cardiac regulations were completely prevented by treatment of the infarcted heart with losartan. The MI-induced collagen deposition in noninfarcted LV myocardium was prevented by 1.6-fold by both low and high doses of spironolactone and by 2.5-fold by losartan. In addition, norepinephrine level was unchanged in infarcted heart but was attenuated by both losartan and spironolactone treatments. CONCLUSIONS: MI is associated with tissue-specific activation of myocardial aldosterone synthesis. This increase is mediated primarily by cardiac angiotensin II via AT1-subtype receptor and may be involved in post-MI ventricular fibrosis and in control of tissue norepinephrine concentration.

Hepatodiaphragmatic interposition of the colon--an unusual case of combined anterior and posterior types treated with an original operative technique: report of a case.

Hepatodiaphragmatic interposition of the colon is rare. The posterior type is rarer than the anterior type. We observed a case of combined anterior and posterior types and used an original operative technique with a Prolene mesh to exclude the dead space and prevent recurrence.

Beta-adrenergic and muscarinic receptor mRNA accumulation in the sinoatrial node area of adult and senescent rat hearts.

The sinoatrial (SA) node is the cardiac pacemaker and changes in its adrenergic-muscarinic phenotype have been postulated as a determinant of age-associated modifications in heart rate variability. To address this question, right atria were microdissected, the SA node area was identified by acetylcholinesterase staining, and, using a RT-PCR method, the accumulation of mRNA molecules encoding beta1- and beta2-adrenergic (beta1- and beta2-AR) and muscarinic (M2-R) receptor was quantified to define the proportion between beta-AR and M2-R mRNAs within the sinoatrial area of adult (3 months) and senescent (24 months) individual rat hearts. In adult hearts, the highest M2-R/beta-AR mRNA ratio was observed within the sinoatrial area compared with adjacent atrial myocardium, while in the senescent hearts, no difference was observed between sinoatrial and adjacent areas. This change was specific of the sinoatrial area since adult and senescent whole atrial or ventricular myocardium did not differ in their M2-R/beta-AR mRNA ratio, and was associated with a fragmentation of acetylcholinesterase staining of the senescent SA node. Quantitative changes in the expression of genes encoding proteins involved in heart rate regulation specifically affect the sinoatrial area of the senescent heart.

[Feasibility and short-term results of the "plug" technique in inguinal hernia. A prospective evaluation]. / Faisabilité et résultats à court terme de la technique du "plug" dans la hernie inguinale. Evaluation prospective.

The aim of this prospective study was to assess the feasibility and postoperative outcome of the "plug" technique in inguinal hernia. One hundred and forty-six consecutive patients were operated for 151 hernias. A plug was applied in 131 cases (86.8%). The Lichtenstein technique was used in 20 cases (13.2%) because of a wide weakness of the posterior wall. Eleven (7.3%) postoperative benign complications occurred. No severe complications were observed and no patient was reoperated. The mean duration of oral analgesia was 2.7 (0-10) days. Mean durations of postoperative hospital stay, time off work and cessation of normal activities were 1.2 (0-4) days, 18.1 (1-37) days and 5.8 (1-18) days, respectively. In conclusion, the "plug" technique is feasible in a wide range of hernias and allows a short hospital stay and an early return to normal activity.

Evidence for an involvement of the neutrophil integrin lymphocyte function-associated antigen-1 in early failure of heart transplants.

BACKGROUND: The adhesion of neutrophils to the coronary vascular wall contributes to reperfusion injury of cardiac allografts. This phenomenon involves interactions between neutrophil beta 2-integrins (CD11a/CD18 [lymphocyte function-associated antigen-1, or LFA-1], CD11b/CD18 [membrane attack complex-1, or MAC-1], and CD11c/CD18 [p150,95]) and their endothelial ligands. Whereas the roles of the common beta-chain (CD18) and of the alpha-subunit of MAC-1 (CD11b) have been studied extensively, the role of the alpha-subunit of LFA-1 (CD11a) remains less well defined. The objective of this study, therefore, was to assess the effects of CD11a blockade on postischemic function and neutrophil infiltration of cardiac allografts. METHODS AND RESULTS: Twenty-six rat hearts were kept in cold storage for 4 hours, heterotopically transplanted in the abdomen of recipient rats, and reperfused for 1 hour. In 10 hearts, a monoclonal antibody against LFA-1 alpha was given as a single intravenous bolus (100 micrograms) 35 minutes before reperfusion. The control groups consisted of 10 hearts that received saline and 6 hearts treated with an isotype-matched, nonbinding antibody (OKT3) administered at the same dosage and schedule as in the anti-LFA-1 alpha group. Before reperfusion, all hearts were instrumented with an intraventricular balloon-tipped catheter to allow serial isovolumic measurements of left ventricular function during reperfusion, after which myocardial accumulation of neutrophils was measured by myeloperoxidase activity. Postischemic heart rate and diastolic pressure were comparable among groups. However, the best recovery of contractility was achieved with anti-LFA-1 alpha treatment. After 60 minutes of reperfusion, dP/dt values were 1680 +/- 66 mm Hg/s-1, 1733 +/- 25 mm Hg/s-1, and 2550 +/- 95 mm Hg/s-1 in the saline, OKT3, and anti-LFA-1 alpha groups, respectively (P < .0001 between anti-LFA-1 alpha and the two control groups). This correlated with a significant (P < .0001) reduction in myocardial accumulation of neutrophils in the anti-LFA-1 alpha group (3.3 +/- 0.1 versus 7.9 +/- 0.6 and 6.7 +/- 0.3 U/100 mg tissue in the saline and OKT3 groups, respectively). CONCLUSIONS: These results suggest the involvement of the alpha-subunit of LFA-1 (CD11a) in neutrophil-mediated reperfusion injury incurred by transplanted hearts. This finding is clinically relevant in view of the recent development of an anti-LFA-1 alpha monoclonal antibody for human use, the cardioprotective effects of which might thus extend beyond the initially intended prevention of lymphocyte-mediated rejection.