Influence of myocardial damage on gene expression of cyclic adenosine monophosphate signal transduction in rats / 中国地方病学杂志

Objective To investigate the relationship between alteration of gene in cyclic adenosine monophosphate(cAMP) signal transduction system in rats after myocardial damage and changes of cardiac function and ventricular remodeling. Methods Twenty eight male Wistar rats weighing 220 g to 250 g were randomly divided into three groups: acute myocardial damage group(AMD, n = 10), chronic myocardial damage group (CMD,n = 9 ) and sham-operation group (control, n = 9). Animal model of acute myocardial damage was established by ligation of rats left coronary artery in the AMD and the CMD groups. Rats in control group were treated similarly, except that the coronary suture was not tied. Hemodynamics and echocardiography were measured before rats were sacrificed 24 hours after operation in control and AMD groups but those in CMD groups were sacrificed 8 weeks later. Cadiocyte apoptosis were estimated by TUNEL method, cAMP levels in heart were tested by radioimmunity and the mRNA expressions for inducible cAMP early repressor (ICER), cAMP response element binding protein (CREB), phosphodiesterase 3A (PDE3A) and bcl-2 were assayed by real-time quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Results The difference of left ventricular end diastolic diameter (LVEDD), left ventricular end diastolic pressure(LVEDP), maximal rising and falling rate of ventricular pressure,left ventricular systolic pressure (LVSP), eject fraction (EF) and fraction shortening (FS) were statistically significant among the three groups(F = 285.9, 196.8, 83.2, 80.4, 54.9, 196.6, 95.2, all P ＜ 0.01). LVEDD[(7.03 ±0.28), (8.20 ± 0.27)mm] and LVEDP[(11.19 ± 2.89), (19.76 ± 3.34)mmHg] in AMD and CMD groups were significantly increased, compared with those in control group[ (5.05 ± 0.30)mm, (- 5.62 ± 3.01 )mmHg, all P ＜0.01 ]. While maximal rising rate[ (2964 ± 449), (2214 ± 434)mmHg/s] and falling rate[(- 2617 ± 441),(- 1891± 424)mmHg/s] of left ventricular pressure, LVSP[ (94.19 ± 4.03), (85.85 ± 6.39)mmHg], EF[ (41.6 ±5.9)%, (35.9 ± 4.1 )%] and FS[ (36.9 ± 4.6)%, (23.1 ± 4.9)%] of left ventricular in the two groups were lower than those in control[(4759 ± 406)mmHg/s, (- 4327 ± 388)mmHg/s, (116.29 ± 8.25)mmHg, (80.9 ± 5.6)%,(53.1 ± 4.3)%, all P ＜ 0.01 ]. These changes in CMD group were more significant than those in AMD groups(P ＜0.05 or P ＜ 0.01 ). The difference of apoptotic index, cAMP and expression of ICER, CREB, PDE3A mRNA and bcl-2 mRNA were statistically significant among the three groups(F= 172.5, 141.0, 540.8, 246.8, 165.1, 563.9,all P＜ 0.01 ). Apoptotic index[ (32.8 ± 4.2)‰, (18.4 ± 3.9)‰] and cAMP in heart[ (9.95 ± 0.30), (5.60 ± 0.25)nmol/kg] in AMD and CMD groups were increased compared to control group[ (3.9 ± 1.7)‰, (2.48 ± 0.29)nmol/kg,all P ＜ 0.01 ], and those in CMD group were lower than in AMD group(all P ＜ 0.01 ). Expression of ICER mRNA (1.434 ± 0.093, 0.942 ± 0.076) and CREB mRNA(5.70 ± 0.50, 2.64 ± 0.51) in AMD and CMD groups were higher, and expression of PDE3A mRNA(48.98 ± 8.14, 16.68 ± 8.46) were lower than those in control group (0.154 ± 0.063, 1.08 ± 0.35, 105.94 ± 12.61, all P ＜ 0.01 ). The three genes in CMD group were fewer than those in AMD group(all P ＜ 0.01 ). bcl-2 mRNA was up regulated in AMD group(4.55 ± 0.27) and was down regulated in CMD group(0.35 ± 0.15) compared to control(2.18 ± 0.30, all P＜ 0.01). Conclusions There is PDE3A-ICER positive-feedback loop leading to myocyte apoptosis and heart failure after myocardial damage. The downregulation of PDE3A mRNA observed in chronic myocardial damage may play a causative role in the progression of ventricular remodeling and heart failure, in part, by inducing ICER mRNA and promoting cardiac myocyte dysfunction.

On angiotensin II receptor distribution after myocardial infarction in dogs / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effects of valsartan on expression of angiotensin II receptors in different regions of heart after myocardial infarction (MI).</p><p><b>METHODS</b>Canines were divided into sham-operated control group (n=7), infarction group (n=7) and Valsartan group (10 mg x kg(-1) x day(-1) for 4 weeks after MI operation, n=7). Four weeks after operation, Doppler tissue imaging (DTI) was used to evaluate regional ventricular function in the noninfarcted myocardium (apical and basal near to the infarction region). The mRNA and protein expressions of angiotensin II type 1 receptor (AT1-R) and angiotensin II type 2 receptor (AT2-R) on the corresponding regions were detected by competitive reverse-transcriptase polymerase chain reaction technique and immunohistochemical technique respectively. Results The protein and mRNA expressions of AT1-R were significantly increased in both apical and basal regions near to the infarction in dogs with MI compared with those in control group (P < 0.05) which could be downregulated by valsartan (P < 0.05). AT2-R expressions were significantly upregulated in infarction group in both apical and basal regions compared with those in control group and valsartan further increased AT2-R expressions in both areas (P < 0.05). Myocardial peak systolic velocity (Sm), myocardial peak early diastolic velocity (Em) and myocardial peak late diastolic velocity (Am) at both apical and basal regions near to the infarction regions were significantly lower in MI group than those in the control group which could be significantly improved by valsartan.</p><p><b>CONCLUSION</b>Both mRNA and protein expressions of AT1-R and AT2-R are upregulated in noninfarcted regions near MI, valsartan improved myocardial function via inhibiting AT1-R upregulation and enhancing AT2-R upregulation.</p>

Relationship between testosterone and indexes indicating endothelial function in male coronary heart disease patients / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To investigate the relationship between androgen level and the indexes indicating endothelial function in male patients with coronary heart disease (CHD).</p><p><b>METHODS</b>We registered the following data for 106 50-70-year-old men: age, weight, blood lipid, including total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol and triglyceride, whether a smoker, sugar levels, blood pressure, free testosterone (FT), vascular cell adhesion molecule-1 (VCAM-1) and the intima-media thickness (IMT) of common carotid artery, common carotid diameter, maximum velocity in systolic phase, minimum velocity in diastolic phase and resistant index. Among the 106 men, 51 were patients with CHD. The relationships between FT level, VCAM-1 concentration and IMT were examined, respectively, using a stepwise linear regression technique among all the 106 men.</p><p><b>RESULTS</b>There was no statistical difference in terms of age, blood pressure, whether a smoker, sugar levels, HDL-C, minimum velocity in diastolic phase, resistant index between male CHD patients and controls; whereas results for weight, total cholesterol, low density lipoprotein cholesterol, triglyceride, VCAM-1 and IMT of male CHD patients were higher than those of controls; FT level and maximum velocity in systolic phase were lower. It was found that among all the objects, FT level was inversely correlated with IMT and VCAM-1 concentration.</p><p><b>CONCLUSION</b>FT level was inversely correlated with VCAM-1 concentration and IMT which are indicators of endothelial function.</p>

Effects of adenovirus-mediated gene transfer of ICOSIg fusion protein on experimental autoimmune myocarditis in Lewis rats / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the effects of adenovirus vector-mediated gene transfer of ICOSIg fusion protein on experimental autoimmune myocarditis (EAM) in Lewis rats.</p><p><b>METHODS</b>Expression vector containing ICOSIg (p-Adeno-ICOSIg) was constructed by fusion of human ICOS and IgGFc segment. Adenovirus vector was digested by PacI enzyme and transfected into HEK 293 cells. Adenovirus expressing ICOSIg was produced. EGFP was constructed into adenovirus vector and used as control. EAM was induced in Lewis rats by injection of porcine cardiac myosin. All immunized Lewis rats were divided into 4 groups. Group A (n = 15) and B (n = 15) received adenovirus containing ICOSIg on day 0 and day 14 respectively to study the effects of costimulatory molecules gene therapy on T cell activation and inflammation; group C (n = 10) and group D (n = 10) received adenovirus containing EGFP on day 0 and day 14 respectively as controls. Group E (n = 10) was normal controls that did not receive immunization. On day 28, all rats were killed after echocardiography examination. Histopathological examination was performed to observe myocardial inflammation. Protein levels of ICOS, ICOSL, B7-1 and B7-2 were detected by Western blot. INF-gamma, IL-2 and IL-4 mRNA were determined by realtime RT-PCR.</p><p><b>RESULTS</b>On day 28, cardiac function was significantly improved and myocardial inflammation significantly attenuated in group B compared to group A, C and D (all P < 0.05). B7-1 expression at protein level was significantly lower in group B than that of group C (P < 0.05). ICOS and ICOSL expressions at protein level were significantly decreased in both group A and B compared with group C and D (P < 0.05). IFN-gamma mRNA level significantly decreased and IL-4 mRNA significantly increased in group A and B compared to group C and D (P < 0.05).</p><p><b>CONCLUSIONS</b>Blockade of costimulatory pathway with gene therapy of ICOSIg alleviated autoimmune inflammatory damage and improved cardiac function in Lewis rats with EAM. Down-regulated costimulatory molecules in the myocardium and reduced inflammatory cytokine secretion might be responsible for the beneficial effects of ICOSIg in this model.</p>

The effects of combined beta(1) adrenergic receptor antagonist and beta(2) adrenergic receptor agonist therapy on cardiac function and myocardial apoptosis in heart failure rats / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the effects of combined beta(1) adrenergic receptor (AR) antagonist with beta(2)AR agonist therapy on cardiac function and cardiomyocyte apoptosis in heart failure rats.</p><p><b>METHODS</b>Heart failure was induced by isoproterenol and rats were randomly divided into metoprolol group (50 mg/kg twice daily/gavage, n = 11), combined treatment group (fenoterol 125 microg/kg and metoprolol 50 mg/kg twice daily/gavage, n = 11) and placebo group (saline, n = 10), another normal 9 male Wistar rats served as control group. After 8 weeks' treatment, cardiac function, apoptosis index (AI), Caspase-3 activity, expression levels of bcl-2 and bax protein, organ weight/body weight and collagen volume fraction (CVF) were evaluated.</p><p><b>RESULTS</b>(1) Left ventricular end diastolic dimension, left ventricular end systolic dimension and E/A ratio were significantly increased and fractional shortening, ejection fraction significantly reduced post isoproterenol (all P < 0.05 vs. control) and these changes were significantly attenuated by metoprolol alone (all P < 0.05 vs. placebo) and further attenuated by the metoprolol and fenoterol combination therapy (all P < 0.05 vs. placebo and metoprolol). (2) Left ventricular weight to body weight ratio, lung weight to body weight ratio and CVF were also significantly reduced in metoprolol and combined treatment group than those in placebo group (all P < 0.01). (3) Compared with placebo group, AI and Caspase-3 activity were significantly lower in metoprolol group (all P < 0.01 vs. placebo) and further reduced in combined treatment group (all P < 0.01 vs. metoprolol). (4) The expression level of bax protein was significantly lower in metoprolol group while bcl-2/bax significantly higher than those in placebo group. These changes were more significant in combined treatment group (all P < 0.01 vs. metoprolol).</p><p><b>CONCLUSIONS</b>beta(1)AR antagonist in combination with beta(2)AR agonist further improved the cardiac function and prevented cardiac remodeling compared with using beta(1)AR antagonist alone in heart failure rats. Downregulated bax and upregulated bcl-2/bax expressions might contribute to the observed beneficial therapy effects by reducing cardiomyocyte apoptosis in these animals.</p>

Chronic blocking of beta 3-adrenoceptor ameliorates cardiac function in rat model of heart failure / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Stimulation of the heart beta 3-adrenoceptor (AR) may result in a negative inotropic effect. Being up-regulated, beta 3-AR plays a more important role in the regulation of cardiac function during heart failure. However, the effect of chronic blocking of beta 3-AR on heart failure has not been fully elucidated. In this study, we used a selective beta 3-AR antagonist SR59230A to treat a well defined heart failure rat model chronically, then evaluated its effect on cardiac function and investigated the mechanism.</p><p><b>METHODS</b>Male Wistar rats were chosen randomly as controls (n = 8). Isoproterenol induced heart failure rats were randomly divided into ISO group (n = 10) and SR group (n = 10). The ISO group received intraperitoneal injection of 1 ml saline twice a day; the SR group received intraperitoneal injection of SR59230A 85 nmol in 1 ml saline twice a day; and the control group received no treatment. The treatment was started 24 hours after the last isoproterenol injection and continued for 7 weeks. Then we measured the following indexes: the ratio of heart weight to body weight (HW/BW) and the ratio of left ventricular weight to body weight (LVW/BW), collagen volume fraction (CVF), left ventricular end diastolic dimension (LVEDd), left ventricular end systolic dimension (LVESd), ejection fraction (EF), fractional shortening (FS) and the ratio of E wave to A wave (E/A), the mRNA and protein expression of beta 3-AR and eNOS, and cGMP level in the heart.</p><p><b>RESULTS</b>The ratios HW/BW and LVW/BW were significantly increased in the ISO group compared with the control group (P < 0.01), but they were limited in the SR group (P < 0.05 compared with the ISO group). CVF increased in the ISO group and the SR group (P < 0.01), but it was significantly attenuated in the SR group (P < 0.01). LVEDd, LVESd and E/A ratio were significantly increased in the ISO group compared with the control group (P < 0.01), while EF and FS were significantly decreased (P < 0.01). Compared with the ISO group, the SR group showed that LVEDd, LVESd and E/A ratio were significantly decreased (P < 0.01), whereas EF and FS were significantly increased (P < 0.01). beta(3)-AR and eNOS mRNA and protein in the ISO group were significantly increased when compared with the control group (P < 0.01). These increases were all attenuated in the SR group compared with the ISO group (P < 0.01). The level of cGMP in myocardial tissue was significantly increased in the ISO group compared with the control group (P < 0.01), whereas SR59230A treatment normalized this increment (P < 0.01).</p><p><b>CONCLUSIONS</b>Chronic blocking of beta 3-AR could ameliorate cardiac function in heart failure rats and its mechanism involves inhibition of the negative inotropic effect and attenuation of cardiac remodeling.</p>

Relationship between plasma brain natriuretic peptide concentration and clinical prognosis in patients of acute myocardial infarction / 中华心血管病杂志

<p><b>OBJECTIVE</b>To evaluate the value of brain natriuretic peptide (BNP) in estimating risk stratification in patients with acute myocardial infarction (AMI) and to determine the relationship between BNP and adverse cardiac events after AMI.</p><p><b>METHODS</b>The 135 subjects were selected into the study, including 25 healthy subjects and 110 patients with a first AMI. The plasma concentrations of BNP were measured at two to four days after infarction in patients and healthy controls. Left ventricular function was evaluated by echocardiography with the parameters of left ventricular ejection function (LVEF) after 3 months. Patients were followed up at 12 months. The main outcome measures were heart failure, left remodeling, mortality and other adverse cardiac events at one year.</p><p><b>RESULTS</b>Plasma BNP concentrations in patients with AMI were much higher than those in the health control people (416.7 +/- 208.0 ng/L versus 61.8 +/- 34.1 ng/L, P < 0.01). The BNP count ranged from 5 to 2500 ng/L in AMI patients. There was no association between the BNP count and mortality rate. The development of new congestive heart failure (CHF) was associated with a higher BNP count (P = 0.02). The development of any of the clinical end points (death/CHF/shock) occurred more frequently in patients with a higher BNP count (13.8% for BNP count of < 100 ng/L, 39.1% for BNP count of 100 - 200 ng/L, 43.3% for BNP count of 200 - 400 ng/L, 46.4% for BNP count of > 400 ng/L; P = 0.019). Plasma BNP concentrations remained independently associated with the development of clinical end points in multivariable model that adjusted for potential confounding variables.</p><p><b>CONCLUSION</b>The results of the present study confirm that the elevated BNP count related to the risk stratification and prognosis in patients with AMI. Elevations in BNP count are associated with a higher incidence of new CHF and adverse clinical outcomes after AMI. It could serve as a strong predictor for the subsequent development of poor outcomes in AMI patients.</p>