scholarly journals Toll-Like Receptor 9 Promotes Cardiac Inflammation and Heart Failure during Polymicrobial Sepsis

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Ralph Lohner ◽  
Markus Schwederski ◽  
Carolin Narath ◽  
Johanna Klein ◽  
Georg D. Duerr ◽  
...  
Keyword(s):  
Heart Failure ◽  
Peritoneal Cavity ◽  
Heart Function ◽  
Bacterial Load ◽  
Systolic Pressure ◽  
Polymicrobial Sepsis ◽  
Toll Like Receptor ◽  
Cardiac Inflammation ◽  
Continuous Release

Background. Aim was to elucidate the role of toll-like receptor 9 (TLR9) in cardiac inflammation and septic heart failure in a murine model of polymicrobial sepsis.Methods. Sepsis was induced via colon ascendens stent peritonitis (CASP) in C57BL/6 wild-type (WT) and TLR9-deficient (TLR9-D) mice. Bacterial load in the peritoneal cavity and cardiac expression of inflammatory mediators were determined at 6, 12, 18, 24, and 36 h. Eighteen hours after CASP cardiac function was monitoredin vivo. Sarcomere length of isolated cardiomyocytes was measured at 0.5 to 10 Hz after incubation with heat-inactivated bacteria.Results. CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart. Eighteen hours after CASP WT mice developed septic heart failure characterised by reduction of end-systolic pressure, stroke volume, cardiac output, and parameters of contractility. This coincided with reduced cardiomyocyte sarcomere shortening. TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function. This was consistent with reduced mortality in TLR9-D compared to WT mice.Conclusions. In polymicrobial sepsis TLR9 signalling is pivotal to cardiac inflammation and septic heart failure.

Impact of exercise training on ventricular properties in a canine model of congestive heart failure

1997 ◽  
Vol 272 (3) ◽  
pp. H1382-H1390 ◽  
Author(s):  
K. Todaka ◽  
J. Wang ◽  
G. H. Yi ◽  
M. Knecht ◽  
R. Stennett ◽  
...  
Keyword(s):  
Heart Failure ◽  
Exercise Training ◽  
Heart Function ◽  
Systolic Pressure ◽  
Cardiac Pacing ◽  
Left Ventricular ◽  
Lv Function ◽  
Myocardial Stiffness

Exercise training improves functional class in patients with chronic heart failure (CHF) via effects on the periphery with no previously documented effect on intrinsic left ventricular (LV) properties. However, because methods used to evaluate in vivo LV function are limited, it is possible that some effects of exercise training on the failing heart have thus far eluded detection. Twelve dogs were instrumented for cardiac pacing and hemodynamic recordings. Hearts were paced rapidly for 4 wk. Six of the dogs received daily treadmill exercise (CHF(EX), 4.4 km/h, 2 h/day) concurrent with rapid pacing, while the other dogs remained sedentary (CHFs). Hemodynamic measurements taken in vivo at the end of 4 wk revealed relative preservation of maximum rate of pressure rise (2,540 +/- 440 vs. 1,720 +/- 300 mmHg/s, P < 0.05) and LV end-diastolic pressure (9 +/- 5 vs. 19 +/- 4 mmHg, P < 0.05) in CHF(EX) compared with CHFs. The hearts were then isolated and cross perfused for in vitro measurement of isovolumic pressure-volume relations; these results were compared with those of six normal dogs (N). Systolic function was similarly depressed in both groups of pacing animals [end-systolic elastance (Ees) values of 1.66 +/- 0.47 in CHFs, 1.77 +/- 0.38 in CHF(EX), and 3.05 +/- 0.81 mmHg/ml in N, with no changes in volume axis interceptors of the end-systolic pressure-volume relationship]. The diastolic myocardial stiffness constant, k, was elevated in CHFs and was normalized by exercise training (32 +/- 3 in CHFs, 21 +/- 3 in CHF(EX), 20 +/- 4 in N). Thus daily exercise training preserved in vivo hemodynamics during 4 wk of rapid cardiac pacing and was accompanied by a significant change in diastolic myocardial stiffness in vitro. These findings suggest that changes in heart function may contribute to the overall beneficial hemodynamic effects of exercise training in CHF by a significant effect on diastolic properties.

scholarly journals Right ventricular function and its coupling with the pulmonary circulation in acute heart failure

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Barki ◽  
M Losito ◽  
M.M Caracciolo ◽  
F Bandera ◽  
M Rovida ◽  
...  
Keyword(s):  
Heart Failure ◽  
Acute Heart Failure ◽  
Acute Phase ◽  
Pulmonary Circulation ◽  
Heart Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Response To Treatment ◽  
The Right ◽  
B Lines

Abstract Background The right ventricle (RV) is extremely sensitive to hemodynamic changes and increased impedance. In acute heart failure (AHF), the development of pulmonary venous congestion and the increase of left ventricular (LV) filling pressures favors pulmonary vascular adverse remodeling and ultimately RV dysfunction, leading to the onset of symptoms and to a further decay of cardiac dynamics. Purpose The aim of the study was to evaluate RV morphology and functional dynamics at admission and discharge in patients hospitalized for AHF, analyzing the role and the response to treatment of the RV and its coupling with pulmonary circulation (PC). Methods Eighty-one AHF patients (mean age 75.75±10.6 years, 59% males) were prospectively enrolled within 24–48 hours from admission to the emergency department (ED). In either the acute phase and at pre-discharge all patients underwent M-Mode, 2-Dimensional and Doppler transthoracic echocardiography (TTE), as well as lung ultrasonography (LUS), to detect an increase of extravascular lung water (EVLW) and development of pleural effusion. Laboratory tests were performed in the acute phase and at pre-discharge including the evaluation of NT-proBNP. Results At baseline we observed a high prevalence of RV dysfunction as documented by a reduced RV systolic longitudinal function [mean tricuspid annular plane systolic excursion (TAPSE) at admission of 16.47±3.86 mm with 50% of the patients exhibiting a TAPSE&lt;16mm], a decreased DTI-derived tricuspid lateral annular systolic velocity (50% of the subjects showed a tricuspid s' wave&lt;10 cm/s) and a reduced RV fractional area change (mean FAC at admission of 36.4±14.6%). Furthermore, an increased pulmonary arterial systolic pressure (PASP) and a severe impairment in terms of RV coupling to PC was detected at initial evaluation (mean PASP at admission: 38.8±10.8 mmHg; average TAPSE/PASP at admission: 0.45±0.17 mm/mmHg). At pre-discharge a significant increment of TAPSE (16.47±3.86 mm vs. 17.45±3.88; p=0.05) and a reduction of PASP (38.8±10.8 mmHg vs. 30.5±9.6mmHg, p&lt;0.001) was observed. Furthermore, in the whole population we assisted to a significant improvement in terms of RV function and its coupling with PC as demonstrated by the significant increase of TAPSE/PASP ratio (TAPSE/PASP: 0.45±0.17 mm/mmHg vs 0.62±0.20 mm/mmHg; p&lt;0.001). Patients significantly reduced from admission to discharge the number of B-lines and NT-proBNP (B-lines: 22.2±17.1 vs. 6.5±5 p&lt;0.001; NT-proBNP: 8738±948 ng/l vs 4227±659 ng/l p&lt;0.001) (Figure 1). Nonetheless, no significant changes of left atrial and left ventricular dimensions and function were noted. Conclusions In AHF, development of congestion and EVLW significantly impact on the right heart function. Decongestion therapy is effective for restoring acute reversal of RV dysfunction, but the question remains on how to impact on the biological properties of the RV. Funding Acknowledgement Type of funding source: None

Abstract 131: C-kit+ Cells Generated From Failed Heart Do Not Improve Failed Heart Function

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Liudmila Zakharova ◽  
Hikmet Nural ◽  
James R Nimlos ◽  
Snjezana Popovic ◽  
Lorraine Feehery ◽  
...  
Keyword(s):  
Heart Failure ◽  
Left Ventricle ◽  
Diastolic Pressure ◽  
Heart Function ◽  
Smooth Muscle Actin ◽  
Functional Improvement ◽  
Gene Expressions ◽  
Coronary Vein ◽  
Mesenchymal Transition

A pilot clinical study using autologous c-Kit+ cells showed improvement in cardiac functions in congestive heart failure (CHF), however, it is unclear if c-Kit+ cells isolated from CHF hearts are equally as potent as cells from controls. To test the potency of CHF c-Kit+ cells, myocardial infarction (MI) was created by permanent ligation of the left anterior descending coronary artery. Six weeks after MI, animals with left ventricle end-diastolic pressure (LVEDP) ≥20 mmHg and scar size ≥30% of left ventricle (LV) were designated as CHF rats. We found that CHF atrial explants generated less c-Kit+ cells compared to shams (15.7% vs. 11% sham vs. CHF). CHF c-Kit+ cells exhibited elevated levels of epicardial to mesenchymal transition markers, including Snail (2.5 fold) and Pai1 (3 fold), while the expression level of epithelial marker, E-cadherin was 3 fold lower in CHF c-Kit+ cells. Moreover, CHF c-Kit+ cells exhibited reduced gene expressions of pluripotency markers; 2.1 fold decrease in Nanog and 4.5 fold decrease in Sox 2 compared to sham cells. To evaluate the potency of the c-Kit+ cells, 1 x 10 6 cells isolated from CHFs or shams were delivered to 3 weeks post-MI CHF hearts. Cells were pre-labeled with GFP to enable their tracing in vivo and delivered to the infarcted myocardium via left coronary vein by a retrograde coronary sinus cell infusion (RCI). RCI delivery resulted in a cell distribution of LV (30%), right atrium (30%) and right ventricle (20%), while only 10% of cells were found in a left atrium. Three weeks after cells delivery, rats transplanted with sham c-Kit+ cells showed improved LVEDP (29.4 ± 6 vs. 11.7 ± 3.5 mmHg, CHF vs. CHF+ sham c-Kit+ cells) and a rise in peak rate of pressure (dPdt max) (3988 ± 520 vs. 5333 ± 597 mmHg/s). In contrast, no functional improvement was detected in rats transplanted with CHF c-Kit+ cells. Histological analysis demonstrated that transplanted c-Kit+/GFP+ cells were mostly incorporated into blood vessels and co-localized with endothelial marker vWf, and α-smooth muscle actin. Our results showed that left coronary vein is an efficient route for c-Kit+ cell delivery and that c-Kit+ cells isolated from CHF rats are less potent when transplanted in chronic heart failure rat model compared to those isolated from control.

Cellular and functional defects in a mouse model of heart failure

2000 ◽  
Vol 279 (6) ◽  
pp. H3101-H3112 ◽  
Author(s):  
Giovanni Esposito ◽  
L. F. Santana ◽  
Keith Dilly ◽  
Jader Dos Santos Cruz ◽  
Lan Mao ◽  
...  
Keyword(s):  
Heart Failure ◽  
Adrenergic Receptor ◽  
Heart Function ◽  
Imaging Techniques ◽  
Single Cells ◽  
Structural Protein ◽  
Muscle Lim Protein ◽  
Intracellular Ca ◽  
Whole Heart

Heart failure and dilated cardiomyopathy develop in mice that lack the muscle LIM protein (MLP) gene (MLP−/−). The character and extent of the heart failure that occurs in MLP−/− mice were investigated using echocardiography and in vivo pressure-volume (P-V) loop measurements. P-V loop data were obtained with a new method for mice (sonomicrometry) using two pairs of orthogonal piezoelectric crystals implanted in the endocardial wall. Sonomicrometry revealed right-shifted P-V loops in MLP−/−mice, depressed systolic contractility, and additional evidence of heart failure. Cellular changes in MLP−/− mice were examined in isolated single cells using patch-clamp and confocal Ca2+ concentration ([Ca2+]) imaging techniques. This cellular investigation revealed unchanged Ca2+ currents and Ca2+ spark characteristics but decreased intracellular [Ca2+] transients and contractile responses and a defect in excitation-contraction coupling. Normal cellular and whole heart function was restored in MLP−/− mice that express a cardiac-targeted transgene, which blocks the function of β-adrenergic receptor (β-AR) kinase-1 (βARK1). These data suggest that, despite the persistent stimulus to develop heart failure in MLP−/− mice (i.e., loss of the structural protein MLP), downregulation and desensitization of the β-ARs may play a pivotal role in the pathogenesis. Furthermore, this work suggests that the inhibition of βARK1 action may prove an effective therapy for heart failure.

scholarly journals Physical Activity and Inhibition of ACE Additively Modulate ACE/ACE-2 Balance in Heart Failure in Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Urszula Tyrankiewicz ◽  
Mariola Olkowicz ◽  
Piotr Berkowicz ◽  
Magdalena Jablonska ◽  
Ryszard T. Smolenski ◽  
...  
Keyword(s):  
Physical Activity ◽  
Heart Failure ◽  
Heart Function ◽  
Combined Treatment ◽  
Training Group ◽  
Cardiac Performance ◽  
Angiotensin Converting Enzyme Inhibition ◽  
Ang Ii ◽  
Spontaneous Physical Activity

Angiotensin-converting enzyme inhibition (ACE-I) and physical activity favorably modulate the ACE/ACE-2 balance. However, it is not clear whether physical activity and ACE-I could synergistically modulate ACE/ACE-2 balance in the course of heart failure (HF). Here, we studied the effects of combined spontaneous physical activity and ACE-I–based treatment on angiotensin (Ang) pattern and cardiac function in a mouse model of HF (Tgαq*44). Tgαq*44 mice with advanced HF (at the age of 12 months) were running spontaneously in a running wheel (exercise training group, ExT) and/or were treated with ACE inhibitor (ACE-I, perindopril, 10 mg/kg) for 2 months. Angiotensin profile was characterized by an LC-MS/MS-based method. The cardiac performance was assessed in vivo by MRI. Ang-(1–7)/Ang II ratio in both plasma and the aorta was significantly higher in the combined treatment group than the ACE-I group or ExT alone, suggesting the additive favorable effects on ACE-2/Ang-(1–7) and ACE/Ang II axes’ balance induced by a combination of ACE-I with ExT. The basal cardiac performance did not differ among the experimental groups of Tgαq*44 mice. We demonstrated additive changes in ACE/ACE-2 balance in both plasma and the aorta by spontaneous physical activity and ACE-I treatment in Tgαq*44 mice. However, these changes did not result in an improvement of failing heart function most likely because the disease was at the end-stage. Ang-(1–7)/Ang II balance represents a valuable biochemical end point for monitoring therapeutic intervention outcome in heart failure.

Transition from compensatory hypertrophy to dilated, failing left ventricles in Dahl salt-sensitive rats

1994 ◽  
Vol 267 (6) ◽  
pp. H2471-H2482 ◽  
Author(s):  
M. Inoko ◽  
Y. Kihara ◽  
I. Morii ◽  
H. Fujiwara ◽  
S. Sasayama
Keyword(s):  
Heart Failure ◽  
Systolic Pressure ◽  
Myocardial Necrosis ◽  
Compensatory Hypertrophy ◽  
High Salt ◽  
High Salt Diet ◽  
Tension Development ◽  
Salt Diet ◽  
The Right

To establish an experimental model for studying a specific transitional stage for compensatory hypertrophy to heart failure, we studied the pathophysiology of the left ventricle (LV) in Dahl salt-sensitive (DS) rats fed a high-salt diet. DS rats fed an 8% NaCl diet after the age of 6 wk developed concentric LV hypertrophy at 11 wk, followed by marked LV dilatation at 15-20 wk. During the latter stage, the DS rats showed labored respiration with LV global hypokinesis. All the DS rats died within 1 wk by massive pulmonary congestion. The dissected left ventricles revealed chamber dilatation and a marked increase in mass without myocardial necrosis. In contrast, corresponding Dahl salt-resistant (DR) rats fed the same diet showed neither mortality nor any of these pathological changes. The in vivo LV end-systolic pressure-volume relationship shifted to the right with a less steep slope in the failing DS rats compared with that in age-matched DR rats. Isometric contractions of LV papillary muscles isolated from these DS rats showed reduced tension development in the failing stage, but normal tension development in the hypertrophied stage. In conclusion, the DS rat fed a high-salt diet is a useful model showing rapidly developing congestive heart failure, in which the transition from compensatory hypertrophy to decompensatory dilatation of LV is easily and consistently manifested.

scholarly journals Loss of Rad-GTPase produces a novel adaptive cardiac phenotype resistant to systolic decline with aging

2015 ◽  
Vol 309 (8) ◽  
pp. H1336-H1345 ◽  
Author(s):  
Janet R. Manning ◽  
Catherine N. Withers ◽  
Bryana Levitan ◽  
Jeffrey D. Smith ◽  
Douglas A. Andres ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Calcium Current ◽  
Ventricular Myocytes ◽  
Morphological Changes ◽  
Heart Function ◽  
Early Time ◽  
Cardiac Phenotype ◽  
Systolic And Diastolic Function

Rad-GTPase is a regulator of L-type calcium current (LTCC), with increased calcium current observed in Rad knockout models. While mouse models that result in elevated LTCC have been associated with heart failure, our laboratory and others observe a hypercontractile phenotype with enhanced calcium homeostasis in Rad−/−. It is currently unclear whether this observation represents an early time point in a decompensatory progression towards heart failure or whether Rad loss drives a novel phenotype with stable enhanced function. We test the hypothesis that Rad−/− drives a stable nonfailing hypercontractile phenotype in adult hearts, and we examine compensatory regulation of sarcoplasmic reticulum (SR) loading and protein changes. Heart function was measured in vivo with echocardiography. In vivo heart function was significantly improved in adult Rad−/− hearts compared with wild type. Heart wall dimensions were significantly increased, while heart size was decreased, and cardiac output was not changed. Cardiac function was maintained through 18 mo of age with no decompensation. SR releasable Ca2+ was increased in isolated Rad−/− ventricular myocytes. Higher Ca2+ load was accompanied by sarco/endoplasmic reticulum Ca2+ ATPase 2a (SERCA2a) protein elevation as determined by immunoblotting and a rightward shift in the thapsigargan inhibitor-response curve. Rad−/− promotes morphological changes accompanied by a stable increase in contractility with aging and preserved cardiac output. The Rad−/− phenotype is marked by enhanced systolic and diastolic function with increased SR uptake, which is consistent with a model that does not progress into heart failure.

scholarly journals Decreased cardiac SERCA2 expression, SR Ca uptake, and contractile function in hypothyroidism are attenuated in SERCA2 overexpressing transgenic rats

2011 ◽  
Vol 300 (3) ◽  
pp. H943-H950 ◽  
Author(s):  
Roland Vetter ◽  
Uwe Rehfeld ◽  
Christoph Reissfelder ◽  
Henry Fechner ◽  
Enn Seppet ◽  
...  
Keyword(s):  
Contractile Function ◽  
Heart Function ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Cardiac Contraction ◽  
Loss Of Function ◽  
Transgenic Rats ◽  
Mrna Ratio ◽  
And Function

The sarco/endoplasmic reticulum (SR) Ca2+-ATPase SERCA2a has a key role in controlling cardiac contraction and relaxation. In hypothyroidism, decreased expression of the thyroid hormone (TH)-responsive SERCA2 gene contributes to slowed SR Ca2+ reuptake and relaxation. We investigated whether cardiac expression of a TH-insensitive SERCA2a cDNA minigene can rescue SR Ca2+ handling and contractile function in female SERCA2a-transgenic rats (TG) with experimental hypothyroidism. Wild-type rats (WT) and TG were rendered hypothyroid by 6- N-propyl-2-thiouracil treatment for 6 wk; control rats received no treatment. In vivo measured left ventricular (LV) hemodynamic parameters were compared with SERCA2a expression and function in LV tissue. Hypothyroidism decreased LV peak systolic pressure, dP/d tmax, and dP/d tmin in both WT and TG. However, loss of function was less in TG. Thus slowed relaxation in hypothyroidism was found to be 1.5-fold faster in TG compared with WT ( P < 0.05). In parallel, a 1.4-fold higher Vmax value of homogenate SR Ca2+ uptake was observed in hypothyroid TG ( P < 0.05 vs. hypothyroid WT), and the hypothyroidism-caused decline of LV SERCA2a mRNA expression in TG by −24% was markedly less than the decrease of −49% in WT ( P < 0.05). A linear relationship was observed between the SERCA2a/PLB mRNA ratio values and the Vmax values of SR Ca2+ uptake when the respective data of all experimental groups were plotted together ( r = 0.90). The data show that expression of the TH-insensitive SERCA2a minigene compensates for loss of expressional activity of the TH-responsive native SERCA2a gene in the female hypothyroid rat heart. However, SR Ca2+ uptake and in vivo heart function were only partially rescued.

Abstract 4031: Nitric Oxide Synthase 3 Deficiency Worsens Myocardial Dysfunction and Survival in Murine Polymicrobial Sepsis

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Masahiko Bougaki ◽  
Robert J Searles ◽  
Jia D Yu ◽  
Gian Paolo Volpate ◽  
Fumito Ichinose
Keyword(s):  
Cardiac Function ◽  
Production Rate ◽  
Myocardial Dysfunction ◽  
Left Ventricular ◽  
Polymicrobial Sepsis ◽  
Atp Production ◽  
Cardiac Inflammation ◽  
Myocardial Mitochondria ◽  
Hemodynamic Study

Background: Myocardial dysfunction during sepsis contributes to the high mortality of patients with septic shock. The role of NOS3 on cardiac function during sepsis remains incompletely understood. Here, we examined impact of NOS3 deficiency on myocardial function and survival during peritonitis-induced polymicrobial sepsis. Methods: Severe polymicrobial sepsis was induced by colon ascendens stent peritonitis (CASP) in wild-type (WT) and NOS3 deficient (KO) mice. Cardiac function was examined both in vivo hemodynamic study and in isolated left ventricular cardiomyocytes, where sarcomere length (SL) and intracellular calcium transients ([Ca 2+ ] i ) were measured by video-edge detection and Fura-2 fluorescence, respectively. Mitochondrial function was assessed by measuring the ATP production rate in isolated mitochondria from left ventricle. Results: Mortality at 24 hours after CASP was higher in KO (15/15, 100%) than in WT (13/20, 65%, P<0.05 vs KO). In vivo hemodynamic study 22 hours after CASP revealed both systolic and diastolic cardiac functions were impaired to a greater extent in KO than in WT. In isolated cardiomyocytes, CASP induced-reduction in percent SL shortening and the peak amplitude of [Ca 2+ ] i was more marked in NOS3KO than in WT. The time constants for SL relengthening and diastolic [Ca 2+ ] i decay were prolonged to a greater extent in KO than in WT after CASP. Cardiac inflammation estimated by expression levels of inflammatory cytokines (TNF-α, IL-1β, IL-6) was more pronounced in KO than in WT. CASP-induced reduction in ATP production rate of myocardial mitochondria was more marked in KO than in WT, which was associated with reduction in mitochondrial complex I activity. Conclusions: These results suggest that NOS3 deficiency aggravates myocardial dysfunction through mitochondrial dysfunction and decreases survival after peritonitis-induced polymicrobial sepsis in mice. Table Hemodynamic and myocyte study 22 hours after CASP or sham

Anti-Apoptotic Effect of Magnolol in Myocardial Ischemia and Reperfusion Injury Requires Extracellular Signal-Regulated Kinase1/2 Pathways in Rat In Vivo

2008 ◽  
Vol 233 (10) ◽  
pp. 1280-1288 ◽  
Author(s):  
Yong Chun Jin ◽  
Kil Jung Kim ◽  
Young Min Kim ◽  
Yu Mi Ha ◽  
Hye Jung Kim ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Infarct Size ◽  
Function Analysis ◽  
Heart Function ◽  
Myocardial Dysfunction ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Ischemia And Reperfusion ◽  
Myocardial Ischemia And Reperfusion

Magnolol, an active component extracted from Magnolia officinalis, has been reported to have protective effect on ischemia and reperfusion (I/R)-induced injury in experimental animals. The aim of the present investigation was to further evaluate the mechanism(s) by which magnolol reduces I/R-induced myocardial injury in rats in vivo. Under anesthesia, left anterior descending (LAD) coronary artery was occluded for 30 min followed by reperfusion for 24 h (for infarct size and cardiac function analysis). In some experiments, reperfusion was limited to 1 h or 6 h for analysis of biochemical and molecular events. Magnolol and DMSO solution (vehicle) were injected intra-peritoneally 1 h prior to I/R insult. The infarct size was measured by TTC technique and heart function was monitored by Millar Catheter. Apoptosis related events such as p-ERK, p-Bad, Bcl-xl and cytochrome c expression were evaluated by Western blot analysis and myocardial caspase-3 activity was also measured. Magnolol (10 mg/kg) reduced infarct size by 50% ( P < 0.01 versus vehicle), and also improved I/R-induced myocardial dysfunction. Left ventricular systolic pressure and positive and negative maximal values of the first derivative of left ventricular pressure (dP/dt) were significantly improved in magnolol-treated rats. Magnolol increased the expression of phosphor ERK and Bad which resulted in inhibition of myocardial apoptosis as evidenced by TUNEL analysis and DNA laddering experiments. Application of PD 98059, a selective MEK1/2 inhibitor, strongly antagonized the effect of magnolol. Taken together, we concluded that magnolol inhibits apoptosis through enhancing the activation of ERK1/2 and modulation of the Bcl-xl proteins which brings about reduction of infarct size and improvement of cardiac function in I/R-induced injury.

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