Mechanism of sudden cardiac death in pigs with viable chronically dysfunctional myocardium and ischemic cardiomyopathy

Pigs with viable chronically dysfunctional myocardium and ischemic cardiomyopathy are at high risk of sudden cardiac death (SCD). We sought to identify the arrhythmic mechanism of SCD, the relation to changes in left ventricular (LV) function, and inducibility of malignant arrhythmias before SCD. Juvenile pigs (n = 72) were instrumented with chronic stenoses on proximal left anterior descending and circumflex arteries. Survival was only 29% 3 mo after instrumentation, and all deaths were sudden and without prodromal symptoms of heart failure. Triphenyltetrazolium chloride staining demonstrated necrosis in only nine animals averaging 2.3 +/- 0.9% of the LV, with no difference between SCD animals and survivors. Implantable loop recorders (n = 13) documented both ventricular fibrillation (n = 6) and bradyasystole (n = 2) as the arrhythmic mechanism of death. Although regional and global function were depressed [anteroseptal wall thickening 1.8 +/- 0.2 vs. 4.2 +/- 0.2 mm in Sham animals (P < 0.001); fractional shortening 21 +/- 2 vs. 31 +/- 1% in Sham animals (P < 0.01)], there were no differences between SCD animals and survivors. LV mass increased in animals with ischemic cardiomyopathy and was greater in animals with SCD (4.0 +/- 0.2 vs. 3.1 +/- 0.1 g/kg in survivors; P < 0.001). Serial programmed ventricular stimulation failed to induce any sustained arrhythmias. We conclude that pigs with viable dysfunctional myocardium and globally reduced LV function have a high rate of SCD with a spectrum of arrhythmias similar to patients with ischemic cardiomyopathy. The risk is independent of necrosis but appears to increase with LV hypertrophy. Like patients with ischemic cardiomyopathy, programmed stimulation is insensitive to predict SCD when viable dysfunctional myocardium is the pathological substrate.     

Coronary plaque injury triggers neutrophil activation in patients with coronary artery disease

Activation of leukocytes, in particular polymorphonuclear neutrophils (PMN), is considered an early event in unstable coronary disease. Upon activation PMN liberate myeloperoxidase (MPO), an enzyme which binds to the vessel wall and depletes vascular NO bioavailability. Using coronary balloon angioplasty as a trigger to provoke coronary plaque injury, we assessed the time course of neutrophil activation, local and peripheral levels of myeloperoxidase, and systemic vascular NO bioavailability in patients with stable coronary artery disease. Twenty-four patients with stable CAD were enrolled prior to undergoing percutaneous interventions (PCI, n=14) and diagnostic coronary angiography (n=10), respectively. Following angioplasty arterial MPO plasma levels increased (231.5+/-67.6 to 273.8+/-80.4 pg/mg protein; P<0.01) whereas MPO levels in the coronary sinus decreased (240.8+/-74.4 vs 205.4+/-60.1 pg/mg protein; P<0.01) in the absence of elevated serum markers for myocardial necrosis. Following PCI, patients revealed impaired vascular NO bioavailability as reflected by reduced brachial flow-mediated dilation (FMD; 6.25+/-3.03 to 4.90+/-2.70%; P<0.01), whereas FMD increased in the angiography group. Coronary plaque injury provokes rapid activation of PMN in the absence of myocardial necrosis; the coronary circulation emerges as a primary site for deposition of MPO following injury of the coronary vessel wall. Activation of PMN with release of MPO is not only restricted to the target site, but can be assessed systemically and may represent a critical mechanistic link for impaired systemic vascular NO bioavailability in patients suffering unstable coronary disease.     

Absence of diastolic mitral annular oscillations is a marker for relaxation-related diastolic dysfunction

Although Doppler tissue imaging frequently indicates the presence of mitral annular oscillations (MAO) following the E' wave (E' wave, etc.), only recently was it shown that annular "ringing" follows the rules of damped harmonic oscillatory motion. Oscillatory model-based analysis of E' and E' waves provides longitudinal left ventricular (LV) stiffness (k'), relaxation/viscoelasticity (c'), and stored elastic strain (x(o)') parameters. We tested the hypothesis that presence (MAO(+)) vs. absence (MAO(-)) of diastolic MAO is an index of superior LV relaxation by analyzing simultaneous echocardiographic-hemodynamic data from 35 MAO(+) and 20 MAO(-) normal ejection fraction (EF) subjects undergoing cardiac catheterization. Echocardiographic annular motion and transmitral flow data were analyzed with a previously validated kinematic model of filling. Invasive and noninvasive diastolic function (DF) indexes differentiated between MAO(+) and MAO(-) groups. Specifically, the MAO(+) group had a shorter time constant of isovolumic relaxation [tau; 51 (SD 13) vs. 67 (SD 27) ms; P<0.01] and isovolumic relaxation time [63 (SD 16) vs. 82 (SD 17) ms; P<0.001] and greater ratio of peak E-wave to peak A-wave velocity [1.19 (SD 0.31) vs. 0.97 (SD 0.31); P<0.05]. The MAO(+) group had greater peak lateral mitral annulus velocity [E'; 17.5 (SD 3.1) vs. 13.5 (SD 3.8) cm/s; P<0.001] and LVEF [71.2 (SD 7.5)% vs. 65.4 (SD 9.1)%; P<0.05] and lower heart rate [65 (SD 9) vs. 74 (SD 9) beats/min, P<0.001]. Additional conventional and kinematic modeling-derived indexes were highly concordant with these findings. We conclude that absence of early diastolic MAO is an easily discernible marker for relaxation-related diastolic dysfunction. Quantitation of MAO via stiffness and relaxation/viscoelasticity parameters facilitates quantitative assessment of regional (i.e., longitudinal) DF and may improve diagnosis of diastolic dysfunction.     

Altered high-energy phosphate metabolism predicts contractile dysfunction and subsequent ventricular remodeling in pressure-overload hypertrophy mice

To study the role of early energetic abnormalities in the subsequent development of heart failure, we performed serial in vivo combined magnetic resonance imaging (MRI) and (31)P magnetic resonance spectroscopy (MRS) studies in mice that underwent pressure-overload following transverse aorta constriction (TAC). After 3 wk of TAC, a significant increase in left ventricular (LV) mass (74 +/- 4 vs. 140 +/- 26 mg, control vs. TAC, respectively; P < 0.000005), size [end-diastolic volume (EDV): 48 +/- 3 vs. 61 +/- 8 microl; P < 0.005], and contractile dysfunction [ejection fraction (EF): 62 +/- 4 vs. 38 +/- 10%; P < 0.000005] was observed, as well as depressed cardiac energetics (PCr/ATP: 2.0 +/- 0.1 vs. 1.3 +/- 0.4, P < 0.0005) measured by combined MRI/MRS. After an additional 3 wk, LV mass (140 +/- 26 vs. 167 +/- 36 mg; P < 0.01) and cavity size (EDV: 61 +/- 8 vs. 76 +/- 8 microl; P < 0.001) increased further, but there was no additional decline in PCr/ATP or EF. Cardiac PCr/ATP correlated inversely with end-systolic volume and directly with EF at 6 wk but not at 3 wk, suggesting a role of sustained energetic abnormalities in evolving chamber dysfunction and remodeling. Indeed, reduced cardiac PCr/ATP observed at 3 wk strongly correlated with changes in EDV that developed over the ensuing 3 wk. These data suggest that abnormal energetics due to pressure overload predict subsequent LV remodeling and dysfunction.     

Skeletal muscle ouabain binding sites are reduced in rats with chronic heart failure.

Intrinsic skeletal muscle abnormalities decrease muscular endurance in chronic heart failure (CHF). In CHF patients, the number of skeletal muscle Na(+)-K(+) pumps that have a high affinity for ouabain (i.e., the concentration of [(3)H]ouabain binding sites) is reduced, and this reduction is correlated with peak oxygen uptake. The present investigation determined whether the concentration of skeletal muscle [(3)H]ouabain binding sites found during CHF is related to 1) severity of the disease state, 2) muscle fiber type composition, and/or 3) endurance capacity. Four muscles were chosen that represented slow-twitch oxidative (SO), fast-twitch oxidative glycolytic (FOG), fast-twitch glycolytic (FG), and mixed fiber types. Measurements were obtained 8-10 wk postsurgery in 23 myocardial infarcted (MI) and 18 sham-operated control (sham) rats. Eighteen rats had moderate left ventricular (LV) dysfunction [LV end-diastolic pressure (LVEDP) < 20 mmHg], and five had severe LV dysfunction (LVEDP > 20 mmHg). Rats with severe LV dysfunction had significant pulmonary congestion and were likely in a chronic state of compensated congestive failure as indicated by an approximately twofold increase in both lung and right ventricle weight. Run time to fatigue and maximal oxygen uptake (VO(2 max)) were significantly reduced ( downward arrow39 and downward arrow28%, respectively) in the rats with severe LV dysfunction and correlated with the magnitude of LV dysfunction as indicated by LVEDP (run time: r = 0.60, n = 21, P < 0.01 and VO(2 max): r = 0.93, n = 13, P < 0.01). In addition, run time to fatigue was significantly correlated with VO(2 max) (r = 0.87, n = 15, P < 0.01). The concentration of [(3)H]ouabain binding sites (B(max)) was significantly reduced (21-28%) in the three muscles comprised primarily of oxidative fibers [soleus: 259 +/- 14 vs. 188 +/- 17; plantaris: 295 +/- 17 vs. 229 +/- 18; red portion of gastrocnemius: 326 +/- 17 vs. 260 +/- 14 pmol/g wet tissue wt]. In addition, B(max) was significantly correlated with VO(2 max) (soleus: r = 0.54, n = 15, P < 0.05; plantaris: r = 0.59, n = 15, P < 0.05; red portion of gastrocnemius: r = 0.65, n = 15, P < 0.01). These results suggest that downregulation of Na(+)-K(+) pumps that possess a high affinity for ouabain in oxidative skeletal muscle may play an important role in the exercise intolerance that attends severe LV dysfunction in CHF.     

Erythropoietin protects the intestine against ischemia/ reperfusion injury in rats

Previous studies have shown that erythropoietin (EPO) has protective effects against ischemia/reperfusion (I/R) injury in several tissues. The aim of this study was to determine whether EPO could prevent intestinal tissue injury induced by I/R. Wistar rats were subjected to intestinal ischemia (30 min) and reperfusion (60 min). A single dose of EPO (5000 U/kg) was administered intraperitoneally at two different time points: either at five minutes before the onset of ischemia or at the onset of reperfusion. At the end of the reperfusion period, jejunum was removed for examinations. Myeloperoxidase (MPO), malondialdehyde (MDA), and antioxidant defense system were assessed by biochemical analyses. Histological evaluation was performed according to the Chiu scoring method. Endothelial nitric oxide synthase (eNOS) was demonstrated by immunohistochemistry. Apoptotic cells were determined by TUNEL staining. Compared with the sham, I/R caused intestinal tissue injury (Chiu score, 3+/-0.36 vs 0.4+/-0.24, P<0.01) and was accompanied by increases in MDA levels (0.747+/-0.076 vs 0.492+/-0.033, P<0.05), MPO activity (10.51+/-1.87 vs 4.3+/-0.45, P<0.05), intensity of eNOS immunolabelling (3+/-0.4 vs 1.3+/-0.33, P<0.05), the number of TUNEL-positive cells (20.4+/-2.6 vs 4.6+/-1.2, P<0.001), and a decrease in catalase activity (16.83+/-2.6 vs 43.15+/-4.7, P<0.01). Compared with the vehicle-treated I/R, EPO improved tissue injury; decreased the intensity of eNOS immunolabelling (1.6+/-0.24 vs 3+/-0.4, P<0.05), the number of TUNEL-positive cells (9.2+/-2.7 vs 20.4+/-2.6, P<0.01), and the high histological scores (1+/-0.51 vs 3+/-0.36, P<0.01), and increased catalase activity (42.85+/-6 vs 16.83+/-2.6, P<0.01) when given before ischemia, while it was found to have decreased the levels of MDA (0.483+/-0.025 vs 0.747+/-0.076, P<0.05) and MPO activity (3.86+/-0.76 vs 10.51+/-1.87, P<0.05), intensity of eNOS immunolabelling (1.4+/-0.24 vs 3+/-0.4, P<0.01), the number of TUNEL-positive cells (9.1+/-3 vs 20.4+/-2.6, P<0.01), and the number of high histological scores (1.16+/-0.4 vs 3+/-0.36, P<0.05) when given at the onset of reperfusion. These results demonstrate that EPO protects against intestinal I/R injury in rats by reducing oxidative stress and apoptosis. We attributed this beneficial effect to the antioxidative properties of EPO.     

Cardiac magnetic resonance imaging of myocardial contrast uptake and blood flow in patients affected with idiopathic or familial dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) is characterized by left ventricular (LV) enlargement with systolic dysfunction, other causes excluded. When inherited, it represents familial dilated cardiomyopathy (FDC). We hypothesized that IDC or FDC would show with cardiac magnetic resonance (CMR) increased myocardial accumulation of gadolinium contrast at steady state and decreased baseline myocardial blood flow (MBF) due to structural alterations of the extracellular matrix compared with normal myocardium. CMR was performed in nine persons affected with IDC/FDC. Healthy controls came from the general population (n = 6) or were unaffected family members of FDC patients (n = 3) without signs or symptoms of IDC/FDC or any structural cardiac abnormalities. The myocardial partition coefficient for gadolinium contrast (lambda(Gd)) was determined by T1 measurements. LV shape and function and MBF were assessed by standard CMR methods. lambda(Gd) was elevated in IDC/FDC patients vs. healthy controls (lambda(Gd) = 0.56 +/- 0.15 vs. 0.41 +/- 0.06; P = 0.002), and correlated with LV enlargement (r = 0.61 for lambda(Gd) vs. end-diastolic volume indexed by height; P < 0.01) and with ejection fraction (r = -0.80; P < 0.001). The extracellular volume fraction was higher in IDC patients than in healthy controls (0.31 +/- 0.05 vs. 0.24 +/- 0.03; P = 0.002). Resting MBF was lower in IDC patients (0.64 +/- 0.13 vs. 0.91 +/- 0.22; P = 0.01) than unaffected controls and correlated with both the partition coefficient (r = -0.57; P = 0.012) and the extracellular volume fraction (r = -0.56; P = 0.019). The expansion of the extracellular space correlated with reduced MBF and ventricular dilation. Expansion of the extracellular matrix may be a key contributor to contractile dysfunction in IDC patients.     

Epicardial adipose tissue assessed by cardiac magnetic resonance imaging in patients with heart failure due to dilated cardiomyopathy

Objective:

We sought to investigate the association of the EAT with CMR parameters of ventricular remodelling and left ventricular (LV) dysfunction in patients with non‐ischemic dilated cardiomyopathy (DCM).

Design and Methods:

One hundred and fifty subjects (112 consecutive patients with DCM and 48 healthy controls) underwent CMR examination. Function, volumes, dimensions, the LV remodelling index (LVRI), the presence of late gadolinium enhancement (LGE) and the amount of EAT were assessed.

Results:

Compared to healthy controls, patients with DCM revealed a significantly reduced indexed EAT mass (31.7 ± 5.6 g/m² vs 24.0 ± 7.5 g/m², p<0.0001). There was no difference in the EAT mass between DCM patients with moderate and severe LV dysfunction (23.5 ± 9.8 g/m² vs 24.2 ± 6.6 g/m², P = 0.7). Linear regression analysis in DCM patients showed that with increasing LV end‐diastolic mass index (LV‐EDMI) (r = 0.417, P < 0.0001), increasing LV end‐diastolic volume index (r = 0.251, P = 0.01) and increasing LV end‐diastolic diameter (r = 0.220, P = 0.02), there was also a significantly increased amount of EAT mass. However, there was no correlation between the EAT and the LV ejection fraction (r = 0.0085, P = 0.37), right ventricular ejection fraction (r = 0.049, P = 0.6), LVRI (r = 0.116, P = 0.2) and the extent of LGE % (r = 0.189, P = 0.1). Among the healthy controls, the amount of EAT only correlated with increasing age (r = 0.461, P = 0.001), BMI (r = 0.426, P = 0.003) and LV‐EDMI (r = 0.346, P = 0.02).

Conclusion:

In patients with DCM the amount of EAT is decreased compared to healthy controls irrespective of LV function impairment. However, an increase in LV mass and volumes is associated with a significantly increase in EAT in patients with DCM.     

Isothiocyanates sensitize the effect of chemotherapeutic drugs via modulation of protein kinase C and telomerase in cervical cancer cells

We determined effects of the vasopeptidase inhibitor (VPI) omapatrilat and angiotensin II type 1 receptor (AT(1)R) blocker (ARB) candesartan in rats during healing between day-2 and day-21 after reperfused myocardial infarction (RMI) on left ventricular (LV) remodeling and function, and regional matrix metalloproteinase (MMP)-9, tissue inhibitor of MMP (TIMP)-3, inducible-nitric-oxide-synthase (iNOS), oxidant-generating myeloperoxidase (MPO), and cytokines tumor-necrosis-factor (TNF)-alpha, interleukin (IL)-6 and IL-10, and transforming-growth-factor (TGF)-beta(1), and collagens. Compared to RMI-placebo, both agents reversed adverse LV remodeling and systolic and diastolic dysfunction, improved collagen remodeling, and normalized MMP-9 (activity, protein, and mRNA), TIMP-3 (protein and mRNA), and iNOS, MPO, TNF-alpha, IL-6, and TGF-beta(1) proteins, and improved MMP-9/TIMP-3 balance and IL-10 levels in previously ischemic zones. The results suggest that modulation of matrix proteases, oxidants, cytokines, and NOSs with omapatrilat and candesartan contribute to reversal of adverse collagen and LV remodeling and attenuation of LV dysfunction during healing after RMI.     

Different expression of adrenoceptors and GRKs in the human myocardium depends on heart failure ethiology and correlates to clinical variables

Downregulation of β(1)- adrenergic receptors (β(1)-ARs) and increased expression/function of G-protein-coupled receptor kinase 2 (GRK2) have been observed in human heart failure, but changes in expression of other ARs and GRKs have not been established. Another unresolved question is the incidence of these compensatory mechanisms depending on heart failure etiology and treatment. To analyze these questions, we quantified the mRNA/protein expressions of six ARs (α(1A), α(1B), α(1D), β(1), β(2), and β(3)) and three GRKs (GRK2, GRK3, and GRK5) in left (LV) and right ventricle (RV) from four donors, 10 patients with ischemic cardiomyopathy (IC), 14 patients with dilated cardiomyopathy (DC), and 10 patients with nonischemic, nondilated cardiopathies (NINDC). We correlated the changes in the expressions of ARs and GRKs with clinical variables such as left ventricular ejection fraction (LVEF) and left ventricular end-systolic and left ventricular end-diastolic diameter (LVESD and LVEDD, respectively). The main findings were 1) the expression of the α(1A)-AR in the LV positively correlates with LVEF; 2) the expression of GRK3 and GRK5 inversely correlates with LVESD and LVEDD, supporting previous observations about a protective role for both kinases in failing hearts; and 3) β(1)-AR expression is downregulated in the LV and RV of IC, in the LV of DC, and in the RV of NINDC. This difference, better than an increased expression of GRK2 (not observed in IC), determines the lower LVEF in IC and DC vs. NINDC.     

Inhibition of vascular peroxidase alleviates cardiac dysfunction and apoptosis induced by ischemia-reperfusion

Myeloperoxidase (MPO) is involved in myocardial ischemia-reperfusion (IR) injury and vascular peroxidase (VPO) is a newly identified isoform of MPO. This study was conducted to explore whether VPO is involved in IR-induced cardiac dysfunction and apoptosis. In a rat Langendorff model of myocardial IR, the cardiac function parameters (left ventricular pressure and the maximum derivatives of left ventricular pressure and coronary flow), creatine kinase (CK) activity, apoptosis, VPO1 activity were measured. In a cell (rat-heart-derived H9c2 cells) model of hypoxia-reoxygenation (HR), apoptosis, VPO activity, and VPO1 mRNA expression were examined. In isolated heart, IR caused a marked decrease in cardiac function and a significant increase in apoptosis, CK, and VPO activity. These effects were attenuated by pharmacologic inhibition of VPO. In vitro, pharmacologic inhibition of VPO activity or silencing of VPO1 expression significantly suppressed HR-induced cellular apoptosis. Our results suggest that increased VPO activity contributes to IR-induced cardiac dysfunction and inhibition of VPO activity may have the potential clinical value in protecting the myocardium against IR injury.     

Cholinergic anti-inflammatory pathway activity and High Mobility Group Box-1 (HMGB1) serum levels in patients with rheumatoid arthritis

High Mobility Group Box-1 (HMGB1) is a cytokine implicated in the pathogenesis of rheumatoid arthritis (RA) and other inflammatory diseases. The cholinergic anti-inflammatory pathway, a vagus nerve-dependent mechanism, inhibits HMGB1 release in experimental disease models. Here, we examine the relationship between vagus nerve activity and HMGB1 in patients with RA. We compared RR interval variability, an index of cardiac vagal modulation, HMGB1 and hsCRP serum levels, and disease activity scores in thirteen RA patients and eleven age- and sex-matched controls. In RA patients, serum levels of HMGB1 and hsCRP were elevated as compared with controls (HMGB1=71 ng/mL [45-99] vs. 18 ng/mL [0-40], P<0.0001; hsCRP=14.5 mg/L [0.7-59] vs. 1 mg/L [0.4-2.9], P<0.001). RR interval variability in RA patients was significantly decreased as compared with controls (HF=38 msec2 [14-80] vs. 288 msec2 [38-364], P<0.0001; rMSSD=20.9+/-9.79 msec, 52.6+/-35.3 msec, P<0.01). HMGB1 levels and RR interval variability were significantly related (rho=-0.49, P<0.01). HMGB1 serum levels significantly correlated with disease activity scores (DAS-28) in patients with RA (P=0.004). The study design does not enable a determination of causality, but the results are consistent with the hypothesis that decreased cholinergic anti-inflammatory pathway activity is associated with increased HMGB1 levels in patients with RA.     

Echocardiographic and cardiac single photon emission computed tomography predictors of left ventricle reverse remodeling after surgical revascularization in patients with ischemic cardiomyopathy and left ventricle systolic dysfunction

Background: The extent of scar or viable hypocontractile myocardial tissue determines postinfarction left ventricle remodeling. The aim of this pilot study was to evaluate the revascularization effect in a group of patients with ischemic cardiomyopathy and LV systolic dysfunction indicated for surgical revascularization, based on evidence for multivessel disease on coronarography and viable myocardium (CMR, SPECT). Aims: To evaluate the revascularization effect in patients with ischemic LV systolic dysfunction and to find preoperative predictors of revascularization effect. Methods: 33 patients (64+/-11 years) with baseline LVEF 34.9+/-9.3 % were included in the study. After a follow-up of 10.7+/-1.2 months, ECHO and SPECT were performed again. The whole group of patients was divided according to revascularization effect (postoperative increase LVEF > 5 % and postoperative decrease LVESV > 5 % compared with baseline) into revascularization responders (R, n = 22) and nonresponders (NR, n = 11). Results: At baseline there was no difference between the subgroups in LVEF (R = 35.7+/-11.0 % vs. NR = 34.3+/-8.2 %), EDV (R = 183.6+/-43.2 vs. NR = 180.2+/-80.5 ml), ESV (R = 118.5+/-40.4 vs. NR = 119.7+/-55.2 ml). The responders showed in a revascularization effect subanalysis differences in the values of LVEF (+9.8+/-8.1 %, p < 0.009), reduction of EDV (-39.9+/-50.9 ml, p = 0.05) and ESV (-35.4+/-42.6 ml, p = 0,002) compared with baseline. The only preoperative parameters predicting LV reverse remodeling were the T(E-Em) (R = -10.6+/-44.1 vs. NR = 29.7+/-43.7 ms, p = 0.037) and the size of fixed perfusion defect (FPD) (R = 11.9+/-13.5 vs. NR = 22.9+/-15.3 % of LV, p = 0.044). Conclusions: Patients with ischemic LV systolic dysfunction with a preoperatively determined myocardial viability develop LV reverse remodeling. The only preoperative parameters predicting LV reverse remodeling were echocardiographic T(E-Em) and FPD on SPECT.     

Head-to-head comparison of BNP and IL-6 as markers of clinical and experimental heart failure: Superiority of BNP

Activation of BNP and IL-6 are hallmarks of left ventricular (LV) dysfunction and congestive heart failure (CHF). To assess the relative activation of BNP and IL-6 in clinical and experimental heart failure, we performed a human study in which plasma N-terminal proBNP (NT-proBNP) and IL-6 were measured in a large group of patients in the chronic phase after myocardial infarction (MI) and an animal study in which LV gene expression of BNP and IL-6 was assessed in rapid ventricular pacing-induced heart failure. In the human study, NT-proBNP and IL-6 were measured by non-extracted, enzyme-linked immunoassay in 845 subjects (n=468 outpatients after MI, MONICA MI register Augsburg; and 377 siblings without MI, control). NT-proBNP (295+/-23pg/mL vs. CTRL 84+/-8, P<0.05) and IL-6 (2.7+/-0.1pg/mL vs. CTRL 2.1+/-0.1, P<0.05) were both elevated in subjects with MI. These increases were particularly pronounced in the presence of concomitant CHF (both P<0.01 vs. CTRL) and LV dysfunction (EF<45%, both P<0.05 vs. CTRL). However, NT-proBNP was significantly correlated with several cardiac structural and functional parameters (EF, LVMI, history of MI, CHF symptoms; all P<0.05) upon regression analysis whereas IL-6 was only correlated with history of MI (P<0.001). Accordingly, MI subjects with symptomatic LV dysfunction were detected by NT-proBNP with a greater sensitivity, specificity, and ROC-area (85%, 88%, and 0.87, respectively) as compared to IL-6 (69%, 53%, and 0.67, respectively). In the animal study, IL-6 and BNP expression were both significantly elevated in CHF (both P<0.05) but with a much greater absolute activation of BNP. In addition, BNP mRNA expression displayed a stronger inverse correlation with LV function (r=-0.74; P<0.001) than IL-6 (r=-0.53; P=0.001) and was a markedly more sensitive and specific molecular marker of LV dysfunction (sensitivity 91%, specificity 100%, ROC-area 0.94) than IL-6 (sensitivity 74%, specificity 83%, ROC-area 0.87). Our animal study provides evidence that IL-6 expression is activated in heart failure but to a significantly lesser degree than that of BNP. Both the stronger expression of BNP and the better correlation with LV function provide the molecular basis for a diagnostic superiority of NT-proBNP in clinical LV dysfunction and heart failure.     

Dextran sulfate inhibits PMN-dependent hydrostatic pulmonary edema induced by tumor necrosis factor.

We tested the hypothesis that neutrophil sequestration is required for the development of tumor necrosis factor- (TNF) induced neutrophil- (PMN) dependent pulmonary edema. TNF (3.2 X 10(5) U/kg ip) was injected into guinea pigs 18 h before lung isolation. After isolation, the lung was perfused with a phosphate-buffered Ringer solution. Dextran sulfate (mol wt 500,000) prevented the changes in pulmonary capillary pressure (Ppc; 8.5 +/- 0.8 vs. 12.8 +/- 0.8 cmH2O), lung weight gain (dW; +0.240 +/- 0.135 vs. +1.951 +/- 0.311 g), and pulmonary edema formation or wet-to-dry wt ratio [(W - D)/D; 6.6 +/- 0.2 vs. 8.3 +/- 0.5] at 60 min induced by PMN infusion into a TNF-pretreated lung. The unsulfated form of dextran had no protective effect [Ppc, dW, and (W - D)/D at 60 min: 11.9 +/- 0.9 cmH2O, +1.650 +/- 0.255 g, and 7.3 +/- 0.2, respectively], whereas the use of another anionic compound, heparin, inhibited the TNF + PMN response [Ppc, dW, and (W - D)/D at 60 min: 5.6 +/- 0.4 cmH2O, +0.168 +/- 0.0.052 g, and 6.4 +/- 0.2, respectively]. Isolated lungs showed increased PMN myeloperoxidase (MPO) activity compared with control in TNF-treated lungs at baseline and 60 min after PMN infusion. Dextran sulfate, dextran, and heparin inhibited the increase in MPO activity. The data indicate that inhibition of PMN sequestration alone is not sufficient for the inhibition of PMN-mediated TNF-induced hydrostatic pulmonary edema and that a charge-dependent mechanism mediates the protective effect of dextran sulfate.     

Cardiac dysfunction in aging conscious rats: altered cardiac cytoskeletal proteins as a potential mechanism

The objective of this study was to test the hypothesis that the mechanism mediating left ventricular (LV) dysfunction in the aging rat heart involves, in part, changes in cardiac cytoskeletal components. Our results show that there were no significant differences in heart rate, LV pressure, or LV diameter between conscious, instrumented young [5.9 +/- 0.3 mo (n = 9)] and old rats [30.6 +/- 0.1 mo (n = 10)]. However, the first derivative of LV pressure (LV dP/dt) was reduced (8,309 +/- 790 vs. 11,106 +/- 555 mmHg/s, P < 0.05) and isovolumic relaxation time (tau) was increased (8.7 +/- 0.7 vs. 6.3 +/- 0.6 ms, P < 0.05) in old vs. young rats, respectively. The differences in baseline LV function in young and old rats, which were modest, were accentuated after beta-adrenergic receptor stimulation with dobutamine (20 mug/kg), which increased LV dP/dt by 170 +/- 9% in young rats, significantly more (P < 0.05) than observed in old rats (115 +/- 5%). Volume loading in anesthetized rats demonstrated significantly impaired LV compliance in old rats, as measured by the LV end-diastolic pressure and dimension relationship. In old rat hearts, there was a significant (P < 0.05) increase in the percentage of LV collagen (2.4 +/- 0.2 vs. 1.3 +/- 0.2%), alpha-tubulin (92%), and beta-tubulin (2.3-fold), whereas intact desmin decreased by 51%. Thus the cardiomyopathy of aging in old, conscious rats may be due not only to increases in collagen but also to alterations in cytoskeletal proteins.     

Ischemic cardiomyopathy in pigs with two-vessel occlusion and viable, chronically dysfunctional myocardium

A chronic left anterior descending coronary artery (LAD) stenosis leads to the development of hibernating myocardium with severe regional hypokinesis but normal global ventricular function after 3 mo. We hypothesized that two-vessel occlusion would accelerate the progression to hibernating myocardium and lead to global left ventricular (LV) dysfunction and heart failure. Pigs were instrumented with a fixed 1.5-mm constrictor on the proximal LAD and circumflex arteries. After 2 mo, there were no overt signs of right-heart failure and triphenyl tetrazolium chloride infarction was trivial (1.4 +/- 0.1% of the LV). Compared with shams, regional function [myocardial systolic excursion (DeltaWT); 2.1 +/- 0.3 vs. 4.6 +/- 0.4 mm, P < 0.05] and resting perfusion (0.90 +/- 0.13 vs. 1.32 +/- 0.09 ml small middle dot min(-1) small middle dot g(-1), P < 0.05) were reduced, consistent with hibernating myocardium. Pulmonary systolic (45.9 +/- 3.3 vs. 36.5 +/- 2.2 mmHg, P < 0.05) and wedge pressures (19.1 +/- 1.6 vs. 11.2 +/- 0.9 mmHg, P < 0.05) were increased with global ventricular dysfunction (ejection fraction 43 +/- 2 vs. 50 +/- 2%, P < 0.05). Early LV remodeling was present with increased cavity size and mass. Reductions in sarcoplasmic reticulum Ca(2+)-ATPase and phospholamban were confined to the dysfunctional LAD region with no change in calsequestrin. Thus combined stenoses of the LAD and circumflex arteries accelerate the development of hibernating myocardium and result in compensated heart failure.     

Determinants of coronary microvascular dysfunction in symptomatic hypertrophic cardiomyopathy

Impaired hyperemic myocardial blood flow (MBF) in hypertrophic cardiomyopathy (HCM), despite normal epicardial coronary arteries, results in microvascular dysfunction. The aim of the present study was to determine the relative contribution of extravascular compressive forces to microvascular dysfunction in HCM. Eighteen patients with symptomatic HCM and normal coronary arteries and 10 age-matched healthy volunteers were studied with PET to quantify resting and hyperemic MBF at a subendocardial and subepicardial level. In HCM patients, MRI was performed to determine left ventricular (LV) mass index (LVMI) and volumes, echocardiography to assess diastolic perfusion time, heart catheterization to measure LV outflow tract gradient (LVOTG) and LV pressures, and serum NH(2)-terminal pro-brain natriuretic peptide (NT-proBNP) as a biochemical marker of LV wall stress. Hyperemic MBF was blunted in HCM vs. controls (2.26 +/- 0.97 vs. 2.93 +/- 0.64 ml min(-1) g(-1), P < 0.05). In contrast to controls (1.38 +/- 0.15 to 1.25 +/- 0.19, P = not significant), the endocardial-to-epicardial MBF ratio decreased significantly in HCM during hyperemia (1.20 +/- 0.11 to 0.88 +/- 0.18, P < 0.01). This pattern was similar for hypertrophied septum and lateral wall. Hyperemic MBF was inversely correlated with LVOTG, NT-proBNP, left atrial volume index, and LVMI (all P < 0.01). Multivariate regression analysis, however, revealed that only LVMI and NT-proBNP were independently related to hyperemic MBF, with greater impact at the subendocardial myocardial layer. Hyperemic MBF is more severely impaired at the subendocardial level in HCM patients. The level of impairment is related to markers of increased hemodynamic LV loading conditions and LV mass. These observations suggest that, in addition to reduced capillary density caused by hypertrophy, extravascular compressive forces contribute to microvascular dysfunction in HCM patients.     

Myeloperoxidase enhances nitric oxide catabolism during myocardial ischemia and reperfusion

Impaired microvascular function during myocardial ischemia and reperfusion is associated with recruitment of polymorphonuclear neutrophils (PMN) and has been attributed to decreased bioavailability of nitric oxide (NO). Whereas myeloperoxidase (MPO), a highly abundant, PMN-derived heme protein facilitates oxidative NO consumption and impairs vascular function in animal models of acute inflammation, its capacity to function in this regard during human myocardial ischemia and reperfusion remains unknown. Plasma samples from 30 consecutive patients (61 +/- 14 years, 80% male) presenting with acute myocardial infarction were collected 9 +/- 4 h after vessel recanalization and compared to plasma from healthy control subjects (n = 12). Plasma levels of MPO were higher in patients than in control subjects (1.4 +/- 0.9 vs 0.3 +/- 0.2 ng/mg protein, respectively, p < 0.0001). The addition of hydrogen peroxide to patient plasma resulted in accelerated rates of NO consumption compared to control subjects (0.53 +/- 0.25 vs 0.068 +/- 0.039 nM/s/mg protein, respectively, p < 0.0001). Myocardial tissue from patients with the same pathology revealed intense recruitment of MPO-positive PMN localized along infarct-related vessels as well as diffuse endothelial distribution of non-PMN-associated MPO immunoreactivity. Endothelium-dependent microvascular function, as assessed by an acetylcholine-dependent increase in forearm blood flow in 75 patients with symptomatic coronary artery disease, inversely correlated with MPO plasma levels (r = -0.75, p < 0.005). Plasma from patients undergoing myocardial reperfusion contained increased levels of MPO, which catalytically consumed NO in the presence of H(2)O(2). Given the correlation between intravascular MPO levels and forearm vasomotor function in patients with coronary artery disease, MPO appears to be an important modulator of vasomotor function in inflammatory vascular disease and a potential therapeutic target for treatment.     

肾上腺髓质素对缺血再灌注后肾功能的保护

目的:探讨肾上腺髓质素(Adrenomedullin,ADM)对缺血再灌注后肾功能的保护作用。方法:在注射外源性ADM蛋白后,建立急性缺血再灌注肾损伤模型,观察ADM对肾功能和氧化损伤指标肌酐(Creatinine,Cr)、尿素氮(Blood Urea Nitrogen,BUN)、髓过氧化物酶(Myeloperoxidase,MPO)、丙二醛(Malondialdehyde,MDA)、超氧化物歧化酶(Superoxide Dismutase,SOD)影响。结果:与I组比较,II组的Cr、BUN、MPO、MDA大幅升高(P0.05),表明急性肾损伤造模成功。与II相比,III组BUN、MPO、MDA明显下降(P0.05),表现出一定的保护作用。结论:ADM对缺血再灌注损伤后的肾功能具有一定的保护作用,其机制可能与减少中性粒细胞浸润,抑制膜脂质的氧化,促进微血管重生修复有关。