Changes of left ventricular myocardial collagen fibers and osteopontin expression in hypertrophic cardiomyopathy / 法医学杂志

OBJECTIVE@#To investigate the changes of collagen fibers and the expression of osteopontin in the left ventricle in cases of hypertrophic cardiomyopathy (HCM), along with the significance of their potential forensic application.@*METHODS@#Fifteen cases of HCM, 15 cases of coronary heart disease with cardiac hypertrophy and 20 cases of traffic accidents were selected as HCM group, coronary heart disease group and control group, respectively. Collagen volume fraction and osteopontin expression were observed and compared by HE staining, Masson trichrome staining and immunohistochemistry methods. Imaging and statistical methods were used for quantitative analysis.@*RESULTS@#Collagen volume fraction in left ventricle of HCM and coronary heart disease were significantly higher than that in the control group (P < 0.05), which was not significantly different between the HCM group and the coronary heart disease group. The integral light density value of osteopontin in left ventricular cardiomyocytes of the HCM group and the coronary heart disease group were significantly higher than that of the control group (P< 0.05), and the value of the HCM group was also significantly higher than that of coronary heart disease group (P < 0.05).@*CONCLUSION@#The increased contents of collagen fibers and the overexpression of osteopontin may play an important role in myocardial fibrosis, and they can be used as markers in aid of diagnosing sudden death due to HCM.

Effects of verapamil preconditioning on cardiac function in vitro and intracellular free Ca2+ and L-type calcium current in rat cardiomyocytes post ischemia-reperfusion injury / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the influences of verapamil preconditioning on cardiac function in vitro and intracellular free Ca2+ and L-type calcium current (I(Ca-L)) in rat cardiomyocytes post ischemia-reperfusion (I/R) injury.</p><p><b>METHODS</b>The isolated rat hearts in control group (37 degrees C Tyrode solution perfusion for 30 min, n = 6), I/R group (no flow for 30 min followed 30 min reperfusion with 37 degrees C Tyrode solution, n = 7) and verapamil preconditioning group [37 degrees C Tyrode solution perfusion for 10 min, adding verapamil (20 micromol/L) to Tyrode solution and perfusion for another 30 min, followed then by 30 min no flow and 30 min reperfusion, n = 7] using Langendorff perfusion system. The fluorescence intensity of intracellular Ca2+ was detected with Fluo-3/AM loading by the laser scanning confocal microscope. The I(Ca-L) was recorded via whole-cell patch clamp technique in enzymatically dissociated single rat ventricular myocytes.</p><p><b>RESULTS</b>As expected, arrhythmias and cardiac dysfunction were shown post I/R injury. The fluorescence intensities of intracellular free Ca2+ in cardiomyocytes were significantly increased compared with control group (P < 0.01). By voltage clamp protocol, peak current densities of I(Ca-L) was significantly reduced and I-V curve significantly elevated. Post I/R injury compared with control group (P < 0.01) which could be reversed by Verapamil preconditioning. Verapamil preconditioning also significantly improved diastolic and systolic functions, and reduced the incidence of arrhythmias.</p><p><b>CONCLUSIONS</b>Myocardial I/R injury might significantly impair heart functions and induce arrhythmias via cellular Ca2+ overload. Verapamil preconditioning could prevent heart I/R injury and reduce arrhythmias by decreasing influx of I(Ca-L), thereby stabilizing cardiomyocytes in myocardial stunning and avoiding occurrence of Ca2+-induced Ca2+ release during I/R injury.</p>

Effects of curcumin on sarcoplasmic reticulum Ca2+-ATPase in rabbits with heart failure / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effects of curcumin on sarcoplasmic reticulum Ca2+-ATPase in heart failure rabbits.</p><p><b>METHODS</b>Rabbit heart failure model was made with aortic regurgitation and abdominal aorta constriction and 40 rabbits were randomly divided into 4 groups including: (1) heart failure treated with curcumin; (2) heart failure treated with placebo; (3) healthy control treated with curcumin and (4) healthy control treated with placebo. All rabbits were administrated with curcumin capsules or placebo capsules 100 mg x kg(-1) x d(-1), respectively. All groups were sacrificed after eight weeks. Myocardial ultrastructural organization was detected by transmission electron microscope. RT-PCR and Western blot were used to measure the expression of sarcoplasmic reticulum Ca2+-ATPase in mRNA and protein levels, respectively. Malachite green colorimetric assay was used to evaluate the activity of sarcoplasmic reticulum Ca2+-ATPase.</p><p><b>RESULTS</b>All detected parameters were similar between control curcumin group and control placebo group. Compared with the control groups (Groups 3 and 4), the heart/body weight ratio was significantly increased in the heart failure-curcumin group (Group 1) and the heart failure-placebo group (Group 2, all P < 0.05), but the ratio was significantly lower in heart failure-curcumin group than in heart failure-placebo group (P < 0.05). The degree of heart failure was decreased by curcumin. Activity and mRNA and protein expression for sarcoplasmic reticulum Ca2+-ATPase were significantly reduced in the heart failure-placebo group and which could be significantly attenuated by curcumin (all P < 0.05).</p><p><b>CONCLUSION</b>Curcumin could improve cardiac function via upregulating the expression of sarcoplasmic reticulum Ca2+-ATPase in this model.</p>

Transmural heterogeneity of calcium handling proteins in the mechanism of porcine model of ventricular fibrillation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the role of heterogeneous expression of calcium handling proteins and spatial heterogeneity of APD restitution in the maintenance mechanism of ventricular fibrillation.</p><p><b>METHODS</b>During programmed electrical simulation, APD restitution curves in the endocardium and epicardium of LV were constructed by plotting APD100 and diastolic interval. APD alternans, delayed after depolarization events were recorded simultaneously. Endocardial and epicardial myocytes were isolated from LV base and apex. Real time-PCR and Western blotting were performed to determine the relative messenger RNA and protein expression levels of calcium handling proteins.</p><p><b>RESULTS</b>The normal hearts have spatial heterogeneity of action potential restitution property and transmural heterogeneity of calcium handling proteins. The slopes of the APD restitution curve in the endocardium were significantly steeper than those in epicardium, and the slopes of APD curve at the LV apex were significantly steeper than those in LV base. However, delayed after depolarization events with larger amplitude and earlier onset consistently occurred in the endocardium of LV base. After programmed electrical simulation, the expression of messenger RNA of RyR2, SERCA2a except for Calstabin2 significantly decreased (by 57% and 41%, respectively, P < 0.05) in the endocardium of the base, while the expression of RyR2, SERCA2a, Calstabin2 significantly increased (by 90%, 78%and 64%, respectively, P < 0.05) in the epicardium of LV base. Although transmural heterogeneity of calcium handling proteins at the LV apex were also observed after rapid pacing, there is no significant differences in the transmural heterogeneity at the LV apex compared to the LV base. The base of LV has unique calcium handling properties.</p><p><b>CONCLUSIONS</b>It has been shown that Calcium cycling could modulate APD restitution property in the intact heart. The interaction between action potential and calcium dynamics instabilities is one of the most important reasons why simple criterion such as the APD restitution slope > 1 may fail to accurately predict the onset of APD alternans.</p>

Action potential duration restitution properties and ventricular fibrillation maintenance mechanism / 中华急诊医学杂志

Objective Toinvestigate the role of dynamic dispersion of electrical recovery in ventricular fibrillation maintenance mechanism.Method Thirty-seren male Yorkshire pigs weighing (23?2.5) kg at 3 months age were randomly divided into Sham-operated group and myocardial infarction group in which the first branch of left anterior descending coronary artery of animals was hgated.After 4 weeks,according to VF occurrence by programmed electrical simulation,the myocardial infarction hearts were divided into two groups, twelve hearts in VF (+) group or six hearts in VF (-) group;and the normal hearts were divided into two groups,five hearts in VF (+) group or ten hearts in VF (-) group.Action potential duration (APD) of subendocardial,subepicardial and mid-layer myocardium of left ventricular anterior wall were recorded simultaneously.The relationship between APD and diastolic interval was quantified as an electrical restitution curve.A Student's-test was used to specify differences between groups.Results At the fourth week after coronary artery ligation,eighteen myocardial infarction hearts and fifteen normal hearts were investigated.When investigating transmural dispersion of reporlarization (TDR) of left ventricle,there was no difference between VF (+) group and VF (-) group [ (20.43?7.01) ms vs (22.32?7.53) ms,P=0.45],although there was statistically significant between normal hearts and myocardial infarction hearts [ (15.66?4.45) ms vs (25.72?6.70) ms,P =0.001].The percentage of APD restitution slope exceed 1 and APD restitution slope maximum were high in the VF (+) group with myocardial infarction hearts and in the VF (+) group with normal hearts, lower in the the VF (-) with normal hearts and lowest in the the VF (-) group with myocardial infarction hearts.Conclusion Dynamic APD restitution properties may play an important role in the ventricular fibrillation maintenance mechanism.The APD restitution slope and not static TDR have prognostic value regarding ventricular fibrillation events.The hearts with the steepest of APD restitution curves has the greatest liability of ventricular fibrillation to happen.