Cardiac Morphometry Research Articles

Abstract 101: Endothelial-Specific Fibroblast Growth Factor Receptor 1 and 2 Deletion Impairs Vascular Remodeling and Recovery in an In Vivo Closed-Chest Model of Cardiac Ischemia-Reperfusion Injury

Introduction: Fibroblast growth factor (FGF) signaling is cardioprotective in various models of myocardial infarction. FGF receptors (FGFRs) are expressed in multiple cell types in the adult heart, but the cell type-specific FGFR signaling which mediates different cardioprotective endpoints is currently unknown. Hypothesis: We hypothesize that endothelial FGFR signaling is essential for vascular remodeling after cardiac ischemia-reperfusion (IR) injury. Methods: We have generated mice with a conditional ablation of the Fgfr1 and Fgfr2 genes in endothelial cells ( Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f ). These mice and littermate controls were subjected to a clinically relevant, in vivo , closed-chest model of cardiac IR injury which includes 90 minutes of occlusion of the left anterior descending artery followed by reperfusion for 7 days. Echocardiography was performed at baseline, day 1, and day 7 of reperfusion, and histological staining was performed on day 7. Results: Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f mice had no baseline abnormalities in cardiac morphometry or function. When subjected to closed-chest, regional cardiac IR injury, Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f mice showed significantly increased infarct size compared to controls at 7 days (37±3% vs. 15±5%, p<0.05) but not 1 day after reperfusion. Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f mice also showed significantly worsened cardiac function (ejection fraction, stroke volume, and fractional shortening) compared to controls at 7 days (p<0.05) but not 1 day after reperfusion. Myocyte cross-sectional area measurement showed no impairment in the cardiac hypertrophic response in the Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f mice. Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f mice have normal vessel density in the non-injured state, but after cardiac IR injury, Tie2-Cre, Fgfr1 f/f , Fgfr2 f/f hearts showed significantly decreased vessel density (both capillaries and smooth muscle actin containing vessels, p<0.05) compared to controls in the peri-infarct area. Conclusions: Ablation of FGFR1 and FGFR2 in endothelial cells results in impaired vascular remodeling, worsened cardiac functional recovery, and increased infarct size without affecting the cardiac hypertrophic response in an in vivo , closed-chest model of cardiac IR injury.

Central zone of myocardial infarction: a neglected target area for heart cell therapy

The purpose of this study was to investigate the fate of transplanted cells in the central zone of myocardial infarction (MI), and to clarify the relationship between the injection-site impact and the efficacy of cell therapy. MI was created by coronary ligation in female rats. Three weeks later, 3-million labelled male bone marrow mesenchymal stem cells (BMSCs) were directly injected into the border (BZC group) or central zone (CZC group) of MI area. As a control, culture medium was injected into the same sites. Cell survival was evaluated by quantitative real-time polymerase chain reaction, and apoptosis was assayed with TUNEL and caspase-3 staining. Four weeks after transplantation, heart function and cardiac morphometry were evaluated by echocardiography and Masson’s Trichrome staining, respectively. Angiogenesis and myogenesis were detected by immunofluorescence staining. After cell transplantation into the border or central zone, there was no cell migration between the different zones of MI. BMSCs in the CZC group exhibited no difference in apoptotic percentage, in the long-term survival, when compared with those in the BZC group. However, they did effectively promote angiogenesis and cellular myogenic differentiation. Although cell delivery in the central zone of MI had no effect on the recovery of heart function compared with the BZC group, the retained BMSCs could still increase the scar thickness, and subsequently exhibit a trend in the reverse remodelling of ventricular dilation. Hence, we concluded that the central zone of MI should not be ignored during cell-based therapy. Multiple site injection (border+central zone) is strongly recommended during the procedure of cell transplantation.

Small Interfering RNA Targeting Focal Adhesion Kinase Prevents Cardiac Dysfunction in Endotoxemia

Sepsis and septic shock are associated with cardiac depression. Cardiovascular instability is a major cause of death in patients with sepsis. Focal adhesion kinase (FAK) is a potential mediator of cardiomyocyte responses to oxidative and mechanical stress. Myocardial collagen deposition can affect cardiac compliance and contractility. The aim of the present study was to determine whether the silencing of FAK is protective against endotoxemia-induced alterations of cardiac structure and function. In male Wistar rats, endotoxemia was induced by intraperitoneal injection of lipopolysaccharide (10 mg/kg). Cardiac morphometry and function were studied in vivo by left ventricular catheterization and histology. Intravenous injection of small interfering RNA targeting FAK was used to silence myocardial expression of the kinase. The hearts of lipopolysaccharide-injected rats showed collagen deposition, increased matrix metalloproteinase 2 activity, and myocyte hypertrophy, as well as reduced 24-h +dP/dt and -dP/dt, together with hypotension, increased left ventricular end-diastolic pressure, and elevated levels of FAK (phosphorylated and unphosphorylated). Focal adhesion kinase silencing reduced the expression and activation of the kinase in cardiac tissue, as well as protecting against the increased collagen deposition, greater matrix metalloproteinase 2 activity, and reduced cardiac contractility that occur during endotoxemia. In conclusion, FAK is activated in endotoxemia, playing a role in cardiac remodeling and in the impairment of cardiac function. This kinase represents a potential therapeutic target for the protection of cardiac function in patients with sepsis.

Heat acclimation and exercise training interact when combined in an overriding and trade-off manner: physiologic-genomic linkage

Combined heat acclimation (AC) and exercise training (EX) enhance exercise performance in the heat while meeting thermoregulatory demands. We tested the hypothesis that different stress-specific adaptations evoked by each stressor individually trigger similar cardiac alterations, but when combined, overriding/trade-off interactions take place. We used echocardiography, isolated cardiomyocyte imaging and cDNA microarray techniques to assay in situ cardiac performance, excitation-contraction (EC) coupling features, and transcriptional programs associated with cardiac contractility. Rat groups studied were controls (sedentary 24°C); AC (sedentary, 34°C, 1 mo); normothermic EX (treadmill at 24°C, 1 mo); and heat-acclimated, exercise-trained (EXAC; treadmill at 34°C, 1 mo). Prolonged heat exposure decreased heart rate and contractile velocity and increased end ventricular diastolic diameter. Compared with controls, AC/EXAC cardiomyocytes demonstrated lower l-type Ca(2+) current (I(CaL)) amplitude, higher Ca(2+) transient (Ca(2+)T), and a greater Ca(2+)T-to-I(CaL) ratio; EX alone enhanced I(CaL) and Ca(2+)T, whereas aerobic training in general induced cardiac hypertrophy and action potential elongation in EX/EXAC animals. At the genomic level, the transcriptome profile indicated that the interaction between AC and EX yields an EXAC-specific molecular program. Genes affected by chronic heat were linked with the EC coupling cascade, whereas aerobic training upregulated genes involved with Ca(2+) turnover via an adrenergic/metabolic-driven positive inotropic response. In the EXAC cardiac phenotype, the impact of chronic heat overrides that of EX on EC coupling components and heart rate, whereas EX regulates cardiac morphometry. We suggest that concerted adjustments induced by AC and EX lead to enhanced metabolic and mechanical performance of the EXAC heart.

Inhibition of cardiac leptin expression after infarction reduces subsequent dysfunction

Leptin is known to exert cardiodepressive effects and to induce left ventricular (LV) remodelling. Nevertheless, the autocrine and/or paracrine activities of this adipokine in the context of post-infarct dysfunction and remodelling have not yet been elucidated. Therefore, we have investigated the evolution of myocardial leptin expression following myocardial infarction (MI) and evaluated the consequences of specific cardiac leptin inhibition on subsequent LV dysfunction. Anaesthetized rats were subjected to temporary coronary occlusion. An antisense oligodesoxynucleotide (AS ODN) directed against leptin mRNA was injected intramyocardially along the border of the infarct 5 days after surgery. Cardiac morphometry and function were monitored by echocardiography over 11 weeks following MI. Production of myocardial leptin and pro-inflammatory cytokines interleukin (IL)-1β and IL-6 were assessed by ELISA. Our results show that (1) cardiac leptin level peaks 7 days after reperfused MI; (2) intramyocardial injection of leptin-AS ODN reduces early IL-1β and IL-6 overexpression and markedly protects contractile function. In conclusion, our findings demonstrate that cardiac leptin expression after MI could contribute to the evolution towards heart failure through autocrine and/or paracrine actions. The detrimental effect of leptin could be mediated by pro-inflammatory cytokines such as IL-1β and IL-6. Our data could constitute the basis of new therapeutic approaches aimed to improve post-MI outcome.

Increased intracellular creatine content is not harmful to the mouse heart

Creatine (Cr) and phosphocreatine (PCr) levels are decreased in heart failure (HF) and reductions in high energy phosphate stores predict the severity of the disease and portend adverse outcomes. To study if cardiac supranormal myocellular Cr concentrations are beneficial, transgenic mouse models that overexpress the creatine transporter (CrT) in the heart have been created. These animals spontaneously developed HF and had shortened life spans, but it is not clear if these outcomes were related to elevations in Cr content, transgene insertion site, or the strain's genetic background. Thus, the question as to whether increases in Cr are protective against cardiac insults remained unanswered. We report the isolation of a new transgenic line that expresses human CrT (under control of the α-myosin heavy chain promoter) in cardiac muscle. Transgene expression was documented by Western blots and immunohistochemistry using a specific rat monoclonal anti-CrT antibody. Conscious echocardiography, and pressure-volume loop studies indicate that cardiac morphometry, and function is normal. HPLC showed that Cr and ADP content are five-fold higher than in control (non-transgenic littermates); PCr and ATP are two-fold higher in young animals, declining to control levels by the time animals are 8 weeks old. These mice are healthy and have normal life spans, indicating that elevated cardiac Cr per se is not deleterious.

Murine echocardiography and ultrasound imaging.

Rodent models of cardiac pathophysiology represent a valuable research tool to investigate mechanism of disease as well as test new therapeutics. Echocardiography provides a powerful, non-invasive tool to serially assess cardiac morphometry and function in a living animal. However, using this technique on mice poses unique challenges owing to the small size and rapid heart rate of these animals. Until recently, few ultrasound systems were capable of performing quality echocardiography on mice, and those generally lacked the image resolution and frame rate necessary to obtain truly quantitative measurements. Newly released systems such as the VisualSonics Vevo2100 provide new tools for researchers to carefully and non-invasively investigate cardiac function in mice. This system generates high resolution images and provides analysis capabilities similar to those used with human patients. Although color Doppler has been available for over 30 years in humans, this valuable technology has only recently been possible in rodent ultrasound. Color Doppler has broad applications for echocardiography, including the ability to quickly assess flow directionality in vessels and through valves, and to rapidly identify valve regurgitation. Strain analysis is a critical advance that is utilized to quantitatively measure regional myocardial function. This technique has the potential to detect changes in pathology, or resolution of pathology, earlier than conventional techniques. Coupled with the addition of three-dimensional image reconstruction, volumetric assessment of whole-organs is possible, including visualization and assessment of cardiac and vascular structures. Murine-compatible contrast imaging can also allow for volumetric measurements and tissue perfusion assessment.

RENAL AND CARDIAC RENALASE EXPRESSION DURING NORMAL AND HIGH-SALT DIETS IN CHRONIC KIDNEY DISEASE RAT MODEL: 2D.06

Renalase, a new regulator of cardiac function and blood pressure (BP), is a monoamine oxidase secreted into blood mainly by the kidney but also by the heart and other tissues. A reduced renalase expression was described in patients and in animal models of chronic kidney disease (CKD) and hypertension. In addition, the renalase knockout mouse is hypertensive and exquisitely sensitive to cardiac ischemia. The aim of the present study was to examine the influence of high sodium intake (HS) on renal and cardiac expression of renalase in rats submitted to 3/4 nephrectomy (3/4nx) and Sham surgery (Sham). Ten days after surgery, 3/4nx and Sham animals received a normal (NS) or a HS diet (40mmol/kg/day) during four days. BP and heart rate (HR) were measured daily using a photoelectric tail-cuff pulse detector. Fourteen days after surgery the animals were sacrificed and left ventricle (LV) and renal cortex (RC) were collected for protein quantification by Western-blotting using the anti-renalase polyclonal primary antibody (1:200, Abcam, UK). In addition, cardiac morphometry and transversal cardiomyocyte diameter (TCD) were also evaluated in all groups. BP, HR and TCD were significantly increased in 3/4nx rats throughout the study. In addition, HS diet significantly increased BP, HR and TCD in both 3/4nx and Sham rats. During NS diet the dimmer form of renalase was significantly reduced in both RC and LV from 3/4nx rats whereas during HS diet both monomer and dimmer renalase forms were reduced in both RC and LV from 3/4nx rats. Moreover, HS diet significantly decreased both monomer and dimmer renalase isoforms in the LV from 3/4nx rats when compared with NS intake. Our results show that the reduced renalase expression in the LV from 3/4nx rats is further accentuated during HS intake. It is suggested that this may contribute to the increased sodium-sensitivity of BP and enhanced cardiovascular risk in CKD.

Effect of pyridostigmine on the sympathovagal balance and cardiac morphometry in heart failure

Sympathovagal balance and cardiac morphometry were evaluated in heart failure (HF) rats, 4 weeks after treatment with the reversible acetylcholinesterase inhibitor pyridostigmine (PYR). HF was produced by left coronary artery ligation under anesthesia. Conscious animals were equipped with catheters in the femoral artery and vein. Methyl atropine and propranolol were used to evaluate the sympathovagal balance and the intrinsic heart rate (IHR). In HF rats PYR reduced heart rate (Control: 335±5; HF: 388±11; HF+PYR: 347±4 bpm), increased vagal tone (Control: 92±13; HF: 40±8; HF+PYR: 107±9 bpm), reduced sympathetic tone (Control: 19±4; HF: 47±9; HF+PYR: 23±5 bpm) and did not change IHR (Control: 377±5; HF: 392±6; HF+PYR: 394±8 bpm) or cardiac/body weight ratio (Control: 2.9±0.1; HF: 3.5±0.1; HF+PYR: 3.6±0.1 mg/g). However, PYR reduced the diameter of the myocytes from the left ventricle (Control: 13.2±0.2; HF: 19.9±0.6; HF+PYR: 17.0±0.5 ìm). In conclusion, it was demonstrated that pyridostigmine increased cardiac vagal tone and reduced the sympathetic tone without changing the IHR of HF rats. In addition, PYR reduced the diameter of the myocytes from the left ventricle.Support: FAPESP, CNPq and CAPES.

Influence of gestational overfeeding on cardiac morphometry and hypertrophic protein markers in fetal sheep

Intrauterine overnutrition is associated with development of cardiovascular disease in adulthood although the underlying mechanism has not been precisely elucidated. This study evaluated the effects of maternal overnutrition on fetal cardiac morphometry and hypertrophy-related mRNA/protein expression. Multiparous ewes were fed either 150% of National Research Council (NRC) nutrient requirements (overfed group) or 100% of NRC requirements (control group) from 60 days before mating to Day 75 (D75) of gestation, when ewes were euthanized. Cardiac morphometry, histology and expression of Akt, forkhead-3a (Foxo3a), glycogen synthase kinase-3β (GSK3β), mammalian target of rapamycin (mTOR), NFATc3 and GATA4, atrial natriuretic factor (ANF), calcineurin A and caspase-8 were examined. Crown rump length, left and right ventricular free wall weights and left ventricular wall thickness were increased in D75 overnourished fetuses. Hematoxylin and eosin staining revealed irregular myofiber orientation and increased interstitial space in heart tissues from overfed group. Masson's trichrome staining displayed myofiber hypertrophy and fascicular disarray in heart tissues from overfed group. Overfeeding significantly enhanced Foxo3a phosphorylation in both ventricles, while protein expression of Akt, Foxo3a, GSK3β and caspase-8 as well as phosphorylated Akt and GSK3β in either ventricle was unaffected. Overfeeding increased left ventricular mTOR, NFATc3 (both total and phosphorylated) and calcineurin A. GATA4, pGATA4 and ANF expression were unchanged in both ventricles. Collectively, our data suggested that overfeeding during early to mid gestation (D75) leads to morphometric changes without overt pathology which may be related to elevated expression of mTOR, NFATc3, calcineurin A and phosphorylation of Foxo3a, mTOR and NFATc3.

Prehypertensive Preconditioning Improves Adult Antihypertensive and Cardioprotective Treatment

Transient prehypertensive treatment (TPT) causes prolonged antihypertensive and cardioprotective effects. Reduced angiotensin sensitivity has been attributed to those effects. We hypothesize that prehypertensive preconditioning by angiotensin II type 1 receptor (AT1R) blockade improves cardiovascular protection of late-onset AT1R blockade in a model of spontaneous hypertensive heart-failure rats (SHHF/Mcc-fa(cp)). TPT (4-8 weeks of age) consisted of AT1R blockade (5 mg/kg candesartan) or vehicle. Candesartan-pretreated SHHF (5 mg/kg/day candesartan; weeks 4-8) received during adulthood (20-28 weeks of age) either candesartan at a dose of 1.5 or 5 mg/kg/day or vehicle. Vehicle-pretreated SHHF received either candesartan (5 mg/kg/day) or vehicle during adulthood. Blood pressure telemetry and longitudinal echocardiography were performed between weeks 20 and 28. Final examination included cardiac and vascular morphometry and measurement of the AT1R signaling and receptor internalization (ATRAP). Combined juvenile and adult AT1R blockade caused lower mean arterial pressure (MAP) than adult AT1R blockade alone (84 +/- 5 versus 97 +/- 5 mm Hg; P < 0.05). Cardiac and vascular hypertrophy was lower. Juvenile treatments were associated with a reduced cardiovascular AT1R expression and enhanced ATRAP expression. Combined juvenile and reduced adult AT1R blockade resulted in MAP similar to that with adult AT1R blockade alone (92 +/- 3 versus 97 +/- 5 mm Hg). We conclude that prehypertensive preconditioning improves adult treatment effects in SHHF. Those effects correlate with reduced cardiovascular AT1R expression and enhanced receptor internalization, suggesting reduced angiotensin sensitivity in pretreated SHHF. Moreover, preconditioning allows a reduction of adult AT1R blockade without loss of protection. Therefore, prehypertensive preconditioning may offer a tool to improve treatment efficacy in humans.

Evaluation of Rosiglitazone Administration on Cardiovascular Function in Severe Obesity

Obese patients have myocardial structural and functional alterations related to insulin resistance. The purpose of the study was to analyze the effects of rosiglitazone, an insulin sensitizer agent, on cardiac morphometry and functioning. In 2 groups of sex- and age-matched, nondiabetic, obese patients (5 men and 7 women, age 19-51 y; group A: body mass index [BMI] 40.6 +/- 3.4 kg/m(2); group B: BMI 42.6 +/- 2.7 kg/m(2)), we evaluated the basal insulin sensitivity index (HOMA[IS]), body composition by bioelectrical impedance analysis and 24-h blood pressure monitoring. Furthermore, all patients underwent conventional 2-Dimensional and color Doppler echocardiography, and pulsed-wave tissue Doppler imaging (TDI). After the baseline evaluation, all patients were put on a hypocaloric diet (70% basal metabolic rate) plus placebo if they were in group A, or plus rosiglitazone (4 mg twice daily; Avandia [GlaxoSmithKline plc., Brentford, Middlesex, United Kingdom]) if they were in group B, for 6 mo. Significant decreases in body weight, total fat mass, BMI, and systolic blood pressure were registered in both groups. Rosiglitazone administration appeared more efficient in improving HOMA(IS) (mean difference: 0.30 +/- 0.19 versus 0.11 +/- 0.21, p < 0.05). Left ventricular (LV) diastolic diameter (49.4 +/- 7.7 versus 52.3 +/- 5.4 mm, p < 0.05) and E wave (0.89 +/- 0.18 versus 0.99 +/- 0.20 m/sec, p < 0.05) increased in the rosiglitazone group due to a rise in preload and water content without peripheral edema. The increase in systolic (Sa) wave velocity in both groups was probably a result of the general improvement in insulin metabolism and the decrease in blood pressure. We confirmed the positive effect of rosiglitazone on glucose metabolism in obese, nondiabetic patients, but changes in insulin sensitivity did not explain the cardiac effects produced by further mechanisms.

Short- and long-term effects of (−)-epicatechin on myocardial ischemia-reperfusion injury

Epidemiological studies have shown a correlation between flavonoid-rich diets and improved cardiovascular prognosis. Cocoa contains large amounts of flavonoids, in particular flavanols (mostly catechins and epicatechins). Flavonoids possess pleiotropic properties that may confer protective effects to tissues during injury. We examined the ability of epicatechin to reduce short-and long-term ischemia-reperfusion (I/R) myocardial injury. Epicatechin (1 mg.kg(-1).day(-1)) pretreatment (Tx) was administered daily via oral gavage to male rats for 2 or 10 days. Controls received water. Ischemia was induced via a 45-min coronary occlusion. Reperfusion was allowed until 48 h or 3 wk while Tx continued. We measured infarct (MI) size (%), hemodynamics, myeloperoxidase activity, tissue oxidative stress, and matrix metalloproteinase-9 (MMP-9) activity in 48-h groups. Cardiac morphometry was also evaluated in 3-wk groups. With 2 days of Tx, no reductions in MI size occurred. After 10 days, a significant approximately 50% reduction in MI size occurred. Epicatechin rats demonstrated no significant changes in hemodynamics. Tissue oxidative stress was reduced significantly in the epicatechin group vs. controls. MMP-9 activity demonstrated limited increases in the infarct region with epicatechin. By 3 wk, a significant 32% reduction in infarct size was observed with Tx, accompanied with sustained hemodynamics and preserved chamber morphometry. In conclusion, epicatechin Tx confers cardioprotection in the setting of I/R injury. The effects are independent of changes in hemodynamics, are sustained over time, and are accompanied by reduced levels of indicators of tissue injury. Results warrant the evaluation of cocoa flavanols as possible therapeutic agents to limit ischemic injury.

Embryonic Cardiac Morphometry in Carnegie Stages 15–23, from the Complutense University of Madrid Institute of Embryology Human Embryo Collection

Aims: We performed a morphometric study of cardiac development on human embryos to complement the scarce data on human embryonic cardiac morphometry and to attempt to establish, from these, algorithms describing cardiac growth during the second month of gestation. Methods: Thirty human embryos from Carnegie stages 15–23 were included in the study. Shrinkage and compression effects from fixation and inclusion in paraffin were considered in our calculations. Results: Growth of the cardiac (whole heart) volume and volume of ventricular myocardium through the Carnegie stages were analysed by ANOVA. Linear correlation was used to describe the relationship between the ventricular myocardium and cardiac volumes. Comparisons of models were carried out through the R² statistic. The relationship volume of ventricular myocardium versus cardiac volume is expressed by the equation: cardiac volume = 0.6266 + 2.4778 volume of ventricular myocardium. The relationship cardiac volume versus crown-rump length is expressed by the equation: cardiac volume = 1.3 e^{0.126 CR length}, where e is the base of natural logarithms. Conclusion: At a clinical level, these results can contribute towards the establishment of a normogram for cardiac development, useful for the design of strategies for early diagnosis of congenital heart disease. They can also help in the study of embryogenesis, for example in the discussion of ventricular trabeculation.

Cardiac remodeling and dysfunction in nephrotic syndrome

There is an increased incidence of heart disease in patients with chronic nephrotic syndrome (NS), which may be attributable to the malnutrition and activated inflammatory state accompanying the sustained proteinuria. In this study, we evaluated renal function, cardiac morphometry, contractile function, and myocardial gene expression in the established puromycin aminonucleoside nephrosis rat model of NS. Two weeks after aminonucleoside injection, there was massive proteinuria, decreased creatinine clearance, and a negative sodium balance. Skeletal and cardiac muscle atrophy was present and was accompanied by impaired left ventricular (LV) hemodynamic function along with decreased contractile properties of isolated LV muscle strips. The expression of selected cytokines and proteins involved in calcium handling in myocardial tissue was evaluated by real time polymerase chain reaction. This revealed that the expression of interleukin-1beta, tumor necrosis factor-alpha, and phospholamban were elevated, whereas that of cardiac sarco(endo)plasmic reticulum calcium pump protein was decreased. We suggest that protein wasting and systemic inflammatory activation during NS contribute to cardiac remodeling and dysfunction.

Loss of myocardial LIF receptor in experimental heart failure reduces cardiotrophin-1 cytoprotection. A role for neurohumoral agonists?

Cardiomyocyte loss is involved in the transition from compensatory left ventricular hypertrophy (LVH) to heart failure (HF). Our aim was to investigate the status of the leukaemia inhibitory factor receptor (LIFR)/gp130 survival pathway and its cytoprotective activity in intact cardiac tissue and in cardiomyocytes obtained from adult spontaneously hypertensive rats (SHR) with LVH (non-failing SHR) and from aged SHR with overt HF (failing SHR). Cardiac morphometry was assayed by planimetry in an image analysis system. mRNA and protein expression were quantified by real time RT-PCR and Western blotting. Receptors were localized by immunocytochemistry. Trypan blue staining, TUNEL, and MTT cell viability assays were employed to study the cytoprotective activity of cardiotrophin-1 (CT-1) in isolated caridomyocytes. Compared to non-failing SHR, failing SHR exhibited enhanced myocardial cell death (p<0.01) demonstrated by the increase in Bax/Bcl-2 ratio, caspase-3 activation and poly (ADP-ribose) polymerase (PARP) fragmentation. Failing SHR had a 7-fold diminished expression (p<0.01) of LIFR, no changes in gp130, and 1.6-fold increased myocardial expression (p<0.01) of CT-1. In cardiomyocytes isolated from non-failing SHR, recombinant CT-1 inhibited apoptotic and non-apoptotic cell death induced by angiotensin II or hydrogen peroxide. LIFR protein was entirely absent in cardiomyocytes isolated from failing SHR, which were resistant to the cytoprotective effects of CT-1. Finally, stimulation of non-failing SHR cardiomyocytes with angiotensin II, aldosterone, norepinephrine or endothelin-1 significantly decreased (p<0.01) LIFR expression. These data suggest that loss of CT-1-dependent survival mechanisms may contribute to the increase of cell death associated with HF in SHR. Neurohumoral activation may contribute to this alteration via suppression of LIFR.

Detection of changes in diastolic function by pulmonary venous flow analysis in women athletes

Background Left ventricular cavity dimension, wall thickness, relaxation, and filling increase with exercise training and have a role in enhancing physical performance. We probed whether changes in diastole may develop separately from those in cardiac morphometry and still contribute to improve physical performance. Challenging diastole by preload reduction with standing and integrating mitral flow analysis with the pulmonary venous flow analysis were viewed as a means for detecting fine diastolic variations. Methods Patterns of mitral, tricuspid, and pulmonary venous flow were evaluated by echo Doppler imaging in the supine and standing positions in 11 long-distance runner women athletes participating in training programs and having no or very mild cardiac morphologic alterations and were compared with those in 11 healthy women active in daily life not participating in training programs. Maximal exercise tolerance was tested in both groups with a treadmill with use of the standard Bruce protocol. Results Echocardiographic left ventricular mass index and mitral and pulmonary flow patterns in athletes and controls were similar while they were supine. Major (P <.01) percent variations and differences between athletes and controls with standing were smaller decrease in right (–12% ± 5% vs –29% ± 5%) and left ventricular (–3% ± 1% vs –9% ± 2%) dimensions and stroke volume (–7% ± 4% vs –23% ± 4%), smaller lengthening of early mitral deceleration (+7% ± 4% vs +18% ± 5%), and isovolumic relaxation (–3% ± 5% vs +15% ± 7%) times. Athletes showed greater reduction in pulmonary S wave peak velocity (–25% ± 10% vs –12.5% ± 7%) and time velocity integral (Si) (–50% ± 9% vs –21% ± 8%), greater increases in pulmonary venous diastolic (D) wave peak velocity(+20% ± 9% vs +12% ± 10%, meters per second), and time velocity integral (Di) (+81% ± 16% vs +27% ± 14%) and greater decrease of S/D(–30% ± 6% vs –18% ± 5%) and Si/Di (–70% ± 10% vs –33% ± 5%) ratios. At multivariate analysis standing Si/Di was the strongest independent predictor of better exercise tolerance (peak exercise time 1035 ± 88 sec in athletes, 751 ± 20 in controls). Conclusions Pulmonary flow analysis in athletes while standing can detect changes in diastolic function that are dissociated from apparent left ventricular morphologic alterations, are undetected in the supine position, and may, in part, determine exercise performance. (Am Heart J 2001;141:139-47.)

Cardiac hypertrophy and telemetered blood pressure 6 wk after baroreceptor denervation in normotensive rats.

We investigated cardiac morphometry 6 wk after sinoaortic baroreceptor denervation (SAD) in Long-Evans rats. SAD (n = 19) was associated with an 11% increase in the weight of the left ventricle (LV) plus septum (P < 0.001) and a 39% increase in that of the right ventricular (RV) free wall (P < 0.001), relative to sham-operated rats (n = 18). RV wall thickness was significantly increased in SAD animals, but there was no difference in the LV wall thickness and volumes of the RV and LV between groups. Constrictor responses to methoxamine and dilation responses to acetylcholine were assessed in an in vitro perfused mesenteric circulation preparation, but neither response was affected by SAD. Baroreceptor denervation was associated with marked and significant increases in the variability (2.8-fold) and daily peak (39 mmHg) levels of telemetered mean arterial pressure (MAP) and small (5%) but significant increases in the daily mean MAP level. Our results are consistent with an effect of increased MAP variability on ventricular weight but cannot rule out possible contributions from other mechanisms.

Magnetic resonance imaging of chronic myocardial infarcts in formalin-fixed human autopsy hearts.

In post-myocardial infarction patients, three-dimensional structure of the infarct as well as infarct size are likely to be important factors affecting mortality, cardiac function, and arrhythmias. Current morphological methods for determining three-dimensional infarct structure in autopsied hearts are inexact and time consuming. The cardiac magnetic resonance imaging techniques used in living patients have shown potential in determining infarct size and structure but have limited resolution for morphometric postmortem studies. The recent development of magnetic resonance microscopy raises the possibility that three-dimensional infarct structure can be quantified at microscopic levels in autopsied hearts. The purpose of this study was to determine the ability of magnetic resonance imaging at different spatial resolutions to differentiate infarcted from noninfarcted myocardium. Magnetic resonance imaging was performed at 2.0 T on cross sections taken from 10 autopsied hearts containing old myocardial infarcts. T1 was derived from six images with repetition times (TRs) for each image ranging from 100 to 3200 milliseconds. T2 was derived from multi-echo images with echo times (TEs) ranging from 10 to 60 milliseconds. Resolution was approximately 400 x 400 microns in 2-mm-thick slices. Sites of infarcted and noninfarcted tissue were identified from histological sections taken from each slice, and the T1 and T2 values of these sites were obtained. Microscopic images were acquired with voxels of 100 x 100 x 625 microns, representing tissue volumes more than 1000-fold smaller than conventional clinical images. In all cases, T1 of infarcted tissue (459 +/- 266 milliseconds, mean +/- SD) was greater than that of noninfarcted tissue (272 +/- 163 milliseconds). Also, in all cases, T2 of infarcted tissue (49 +/- 14 milliseconds) was greater than that of noninfarcted tissue (35 +/- 8 milliseconds). T1 and T2 values for infarcted tissue are significantly different from those of noninfarcted tissue (P < .001). Based on these findings, it should be possible to develop techniques to perform three-dimensional imaging and quantitation of infarcts with a resolution of 400 microns or less. When volumetric three-dimensional imaging was performed using a T1-weighted sequence, the resulting 256(3) arrays supported isotropic resolution at 400 microns (voxel volume, 0.064 mm3). Subsequent volume rendering using a compositing algorithm clearly shows the infarcted areas in three dimensions. The techniques demonstrate the potential for quantitative three-dimensional cardiac morphometry using magnetic resonance imaging.