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ABSTRACT: Accumulating evidence suggests that the adrenergic receptors (ARs) play an important role in cardiac diseases. The expression of β3-AR has been recently demonstrated in atria, however, its role in atrial structural remodeling of atrial fibrillation (AF) is unclear. Therefore, the present study was designed to investigate the role of β3-AR in atrial structural remodeling in AF and to clarify its possible mechanisms. Twenty-eight dogs were randomly divided into sham, pacing, β3-AR agonist (BRL37344) and β3-AR antagonist (L748337) groups. AF was induced by rapid atrial pacing at 600 beats per minute for 3 weeks and evaluated by determining the ultrastructure and function of atria. The expression of β3-AR and p38 mitogen-activated protein kinase (MAPK) was examined by western blot, immunohistochemistry and real-time RT-PCR. Additionally, the extent of oxidative stress was tested. We found the atrial enlargement and dysfunction in pacing group. Moreover, atrial interstitial fibrosis, apoptosis and oxidative stress were increased and the levels of β3-AR and phosphorylated p38 MAPK were increased after pacing. Activation of β3-AR exacerbated the pathologic changes and oxidative stress, which were effectively inhibited by L748337. We concluded that β3-AR was upregulated in paced atria, which contributed to oxidative stress and exacerbated atrial structural remodeling by regulating p38 MAPK. Our study provides novel insights into the pharmacological role of β3-AR in AF.
Cellular Physiology and Biochemistry 07/2012; 30(2):372-81. · 2.86 Impact Factor
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Jianqiang Li,
Yue Li,
Jie Liu,
Hongbo Shan,
Weimin Li,
Jiyi Zhao,
Yongtai Gong, Li Sheng,
Deli Dong,
Baoxin Li,
Baofeng Yang
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ABSTRACT: Previous studies have demonstrated that elevated thyroid hormones lead to atrial electrical remodelling, which makes the atria prone to fibrillation. The present study was undertaken to clarify whether atrial structural and sympathetic remodelling, which also contribute to the development of atrial fibrillation, occur during hyperthyroidism. Fourteen dogs were divided into a hyperthyroid group and a euthyroid group. Dogs in the hyperthyroid group were given levothyroxine sodium tablets for 10 weeks, while those in the euthyroid group received starch placebos. Parameters defining thyroid status were recorded weekly. Electrophysiological properties, tissue structure and ultrastructure, sympathetic innervation, levels of apoptosis-related proteins and calpain-1 were assessed in the atria. After the 10-week period of thyroid feeding, atrial dilatation and dysfunction were observed in the hyperthyroid group. Compared with atrial myocytes obtained from the euthyroid group, those from the hyperthyroid group had fewer sarcomeres and showed a significant increase in myolysis, fibrosis, and apoptosis. The levels of caspase-3, bax, calpain-1, and tyrosine hydroxylase (a marker of sympathetic nerves) were increased in the hyperthyroid group, while that of bcl-2 was decreased. We conclude that elevated thyroid hormones contribute to atrial structural and sympathetic remodelling, which have the potential to promote the development of atrial fibrillation.
Acta histochemica 01/2010; · 1.23 Impact Factor
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ABSTRACT: This study was designed to evaluate the effects of a calpain inhibitor on cardiac muscle apoptosis in rapid pacing canine atrial fibrillation (AF) models.
Twenty one dogs were divided into three groups: a sham operation group, a control AF group and a calpain inhibitor group. Sustained AF was induced by rapid right atrium pacing at 600 beats per minute. N-Acetyl-Leu-Leu-Met (1.0 mg/kg/day) was administered in the calpain inhibitor group for three weeks. The activity of calpain I and cardiomyocyte apoptosis were measured by fluorometry and TUNEL assay, respectively. Protein expression of caspase-3 was detected by Western blot. The localizations of caspase-3, caspase-8, bcl-2 and ARC were assessed by immunohistochemistry.
In comparison to the sham operation group, the activity of calpain I was significantly increased in the control AF group (2.3 fold, p < 0.001), and decreased in the calpain inhibitor group (1.1 fold, p < 0.005). The calpain activity correlated with the apoptosis index (r = 0.9, p < 0.05). The apoptosis index was 1.0 +/- 0.2%, 11.8 +/- 6.8% and 3.5 +/- 2.1% in the sham operation group, control AF group and calpain inhibitor group, respectively. In the sham operation group, control AF group and calpain inhibitor group, the expressions of caspase-3 (13.0 +/- 1.9%, 52.8 +/- 4.3% and 33.6 +/- 3.7%), caspase-8 (40.1 +/- 5.3%, 92.6 +/- 6.5% and 55.3 +/- 5.9%), bcl-2 (65.8 +/- 6.1%, 52.0 +/- 5.7% and 69.9 +/- 5.3%) and ARC (70.2 +/- 8.6%, 68.8 +/- 7.3% and 81.5 +/- 8.8%) were calculated as immunohistochemical indexes, respectively.
The calpain inhibitor N-Acetyl-Leu-Leu-Met attenuated apoptosis through a complicated network of apoptosis-related proteins, which may result in improvement of structural remodeling in atrial fibrillation.
Cardiovascular Drugs and Therapy 10/2009; 23(5):361-8. · 3.13 Impact Factor
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ABSTRACT: Oxidative stress has recently been implicated in atrial fibrillation (AF); however, the mechanisms remain unclear. Herein, we hypothesize that probucol can attenuate atrial structure remodeling.
Twenty dogs were randomly divided into sham-operated, control, and probucol-treated groups. We identified apoptosis and histopathological changes in the atria. Oxidative stress was measured by lipid peroxidation and echocardiographic examinations were performed.
Atrial apoptosis indexes were dramatically decreased in the probucol-treated group compared to the control group. Relative to the control group, the percentage of myolysis was dramatically decreased in the probucol-treated group (p < 0.01). There was less lipid peroxidation in the probucol-treated group than the control group. Atrial function was dramatically elevated in the probucol-treated group.
The results of this study indicate that the antioxidant probucol suppresses atrial structural remodeling and may act as a new therapy for AF.
Biochemical and Biophysical Research Communications 04/2009; 381(2):198-203. · 2.48 Impact Factor
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Yong-tai Gong,
Wei-min Li,
Yue Li,
Shu-sen Yang, Li Sheng,
Ning Yang,
Hong-bo Shan,
Hong-jie Xue,
Wei Liu,
Bao-feng Yang,
De-li Dong,
Bao-xin Li
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ABSTRACT: We hypothesize that increased atrial oxidative stress and inflammation may play an important role in atrial nerve sprouting and heterogeneous sympathetic hyperinnervation during atrial fibrillation (AF). To test the hypothesis, we examined whether the antioxidant and anti-inflammatory treatment with probucol attenuates atrial autonomic remodeling in a canine model of AF produced by prolonged rapid right atrial pacing.
Twenty-one dogs were divided into a sham-operated group, a control group and a probucol group. Dogs in the control group and probucol group underwent right atrial pacing at 400 beats per minute for 6 weeks, and those in the probucol group received probucol 1 week before rapid atrial pacing until pacing stopped. After 6-week rapid atrial pacing, general properties including left atrial structure and function, atrial hemodynamics and the inducibility and duration of AF were measured in all the groups. Atrial oxidative stress markers and serum C-reactive protein (CRP) concentration were estimated. The degree of nerve sprouting and sympathetic innervation at the right atrial anterior wall (RAAW) and the left atrial anterior wall (LAAW) were quantified by immunohistochemistry, atrial norepinephrine contents were also detected. Atrial beta-nerve growth factor (beta-NGF) mRNA and protein expression at the RAAW and LAAW were assessed by real-time quantitative RT-PCR and Western blotting respectively.
Atrial tachypacing induced significant nerve sprouting and heterogeneous sympathetic hyperinnervation, and the magnitude of nerve sprouting and hyperinnervation was higher in the RAAW than in the LAAW. Atrial beta-NGF mRNA and protein levels were significantly increased at the RAAW and LAAW, and the upregulation of beta-NGF expression was greater at the RAAW than at the LAAW in the control group. The beta-NGF protein level was positively correlated with the density of sympathetic nerves in all groups. Probucol decreased the increase of CRP concentration and attenuated atrial oxidative stress caused by atrial tachypacing. In addition, probucol could effectively inhibit atrial beta-NGF upregulation, significantly attenuate atrial nerve sprouting and heterogeneous sympathetic hyperinnervation, and dramatically reduce the inducibility and duration of AF.
The atrial over-expression of beta-NGF possibly caused by increased oxidative stress and inflammation may be the main mechanism underlying atrial autonomic remodeling during AF. Probucol attenuates atrial autonomic remodeling possibly by its antioxidant and anti-inflammatory actions.
Chinese medical journal 02/2009; 122(1):74-82. · 0.86 Impact Factor
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ABSTRACT: It has been demonstrated that stent implantation in a myocardial bridge is associated with a high restenosis rate; however, coronary perforation caused by stent implantation has been reported. The present report describes two myocardial bridge cases with severe coronary rupture soon after stent implantation. Previous studies have reported that the diameter of the bridge vessels was less than that of the proximal and distal vessels; thus, coronary perforation may be due to stent oversizing. To determine the risks and benefits associated with this therapeutic option, interventional therapy should be critically evaluated, and careful selection of balloon and drug-eluting stent size using intravascular ultrasound is recommended.
The Canadian journal of cardiology 12/2008; 24(11):e80-1. · 3.36 Impact Factor
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ABSTRACT: To evaluate the effects of oxidative stress on the protein expression of atrial calpain I and pathohistological and ultrastructural changes of atrial myocardium in atrial fibrillation (AF).
Twenty dogs were all implanted with pacemaker in a subcutaneous pocket and attached to a screw-in epicardial lead in right atrial appendage. They were randomly divided into 3 groups: sham-operation group (n = 6 without pacing), control group (n = 7 per minutes for 6 weeks), and probucol group (n = 7, pacing 1 week after recovery for 6 weeks, and administration of probucol 100 mg x kg(-1) x d(-1) 1 week before pacing till the end of pacing). One thin silicon plaque containing 4 pairs of electrodes were sutured to the right atrium. The dogs in control group, probucol group were paced at 400 beats per minutes for 6 weeks. Then the dogs were killed with their hearts taken out. The expression of atrial calpain I was measured by Western-blotting and immunohistochemistry. The pathohistological and ultrastructural changes in atrial tissue were tested by light and electron microscopy. The inducibility and duration of AF were measured in the control group and probucol group. The indexes of oxidative stress total anti-oxidation capability (T-AOC), malonyldiadehyde (MDA), and scavenging activities of superoxide anion (O2-) radical were measured by colorimetric method.
The percentage of myolysis in the left and right atria of the control group were (53.6 +/- 11.8)% and. (58.5 +/- 9.2)% respectively, significantly higher than those of the sham operation group [(4.4 +/- 3.1)% and (4.1 +/- 2.9)% respectively, both P < 0.01]. The percentage of myolysis in the left and right atria of the probucol group were (12.3 +/- 3.2)% and (12.0 +/- 2.6)% respectively, both significantly lower than those of the control group (both P < 0.01). The protein expression of calpain I of the control group was significantly higher than that of the sham-operation group, and the protein expression of calpain I of the probucol group was significantly lower than that of the control group. The AF inducibility rate after pacing of the probucol group was 60%, significantly lower than that of the control group (92.9%, P < 0.01). The average AF duration time after pacing of the probucol group was (601 +/- 328) s, significantly shorter than that of the control group (1458 +/- 498) s. The indexes of oxidative stress in probucol group were lower than the level in control group. The MDA levels of the probucol group was (3.08 +/- 0.20) mmol/mg protein, significantly lower than that of the control group (4.15 +/- 0.23) mmol/mg protein). The anti-O2- and T-AOC level of the probucol group were 279 +/- 20 U/g protein and 30.5 +/- 1.3 nmol/mg protein, both significantly higher than those of the control group (215 +/- 16 U/g protein and 25.6 +/- 1.5 nmol/mg protein respectively, both P < 0.01). There were more sarcomere vacuolization and dissolution in atrial myocytes in the control group than in the sham operation group. And the pathohistological and ultrastructural changes of the probucol were lighter than those of the control group.
Probucol prevents the pathohistological and ultrastructural changes in atrial myocardium by inhibiting calpain I expression, thus suppressing atrial structural remodeling, and preventing the induction and promotion of AF.
Zhonghua yi xue za zhi 05/2008; 88(14):985-9.
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Hong-jie Xue,
Wei-min Li,
Yue Li,
Yong-tai Gong,
Bao-feng Yang,
Cheng-luo Jin, Li Sheng,
Shan Chu,
Li Zhang,
Hong-bo Shan,
Jie Liu
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ABSTRACT: Atrial fibrillation (AF) is accompanied by atrial structural remodeling. Calpain activity is induced during AF. To test a causal relationship between calpain activation and atrial structural changes, N-acetyl-Leu-Leu-Met (ALLM), a calpain inhibitor, was utilized in a canine AF model.
Fifteen dogs were randomly divided into 3 groups: sham-operated group, control group and calpain inhibitor group; each with 5 dogs. Sustained AF was induced by rapid right atrium pacing at 600 beats per minute for 3 weeks. ALLM was administered at a dosage of 1.0 mg x kg(-1) x d(-1) in the calpain inhibitor group. Three weeks later, the proteolysis, protein expression of TnT and myosin, calpain I localization and expression and structural changes were examined in left atrial free walls, right atrial free walls and the interatrial septum respectively. Atrial size and contractile function were also measured by echocardiography.
Long-term rapid atrial pacing induced marked structural changes such as enlarged atrial volume, myolysis, degradation of TnT and myosin, accumulation of glycogen and changes in mitochondrial shape and size, which were paralleled by an increase in calpain activity. The positive correlation between calpain activity and the degree of myolysis (r(s) = 0.90 961, P < 0.0001) was demonstrated. In addition to structural abnormalities, pacing-induced atrial contractile dysfunction was observed in this study. The pacing-induced atrial structural alterations and loss of contractility were partially prevented by the calpain inhibitor ALLM.
Activation of calpain represents key features in the progression towards overt structural remodeling. Calpain inhibitor, ALLM, suppressed the increased calpain activity and reversed structural remodeling caused by sustained atrial fibrillation in the present model. Calpain inhibition may therefore provide a possibility for therapeutic intervention in AF.
Chinese medical journal 01/2008; 121(1):32-7. · 0.86 Impact Factor
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ABSTRACT: To test the causal relationship between calpain activation and atrial structural changes during atrial fibrillation (AF).
The tip of a spiral mono-polar pacing lead was fixed to the right atrial appendages of 15 dogs randomly divided into 3 equal groups: calpain inhibitor group, undergoing continuous pacing with the impulse of 600 beats/min for 3 weeks and intravenous injection of N-acetyl-Leu-Leu-Met (ALLM), a calpain inhibitor for 3 weeks; control group, undergoing continuous pacing and intravenous injection of dimethyl sulfoxide (DMSO; and sham operation group, given DMSO injection without pacing. Ultrasonography was used to observe the changes of the structures of left atrium and left atrial appendage and the heart function as well. Specimens of atrial muscles were obtained. Calpain 1 activity was detected by Suc-Leu-Leu-Val-Tyr-7-amino-4-methyl-coumarin method. HE staining was conducted to observe the myolysis. Western blotting was used to detect the protein expression of troponin I (TnI) and myosin.
The left atrial ejection fraction (LAEF) of the ALLM group was (41 +/- 6)%, significantly higher than that of the control group [(34 +/- 9)%, P < 0.05]. The left atrial appendage ejection fraction (LAAEF) of the ALLM group was (41 +/- 6)%, significantly higher than that of the control group [(35 +/- 6)%, P < 0.05]. Myolysis was extensive in the control group [(71.5 +/- 10.2)%], relatively rare in the ALLM group [(12.3 +/- 16.5)%], and was not seen in the sham operation group, with significantly differences among the 3 groups (all P < 0.01). The calpain 1 activity was positively correlated with the degree of myolysis (r(s) = 0.90 961, P < 0.01). The TnI level of the control group was (43 +/- 12)% that of the sham operation group (P = 0.001), the TnI level of the ALLM group was (51 +/- 11)% that of the sham operation group (P = 0.002) and was significant higher than that of the control group (P = 0.01). The level of myosin of the control group was (51 +/- 11)% that of the sham operation group (P = 0.002), and that of the ALLM group was (149 +/- 33)% that of the control group (P = 0.005).
Activation of and upregulation of expression of calpain participate in the structural remodeling of left atrial cardiac muscle and contractile dysfunction. Calpain inhibitor suppresses the increased calpain activity and reverses the structural remodeling of sustained atrial fibrillation. Calpain inhibition may therefore provide a possibility for therapeutic intervention in AF.
Zhonghua yi xue za zhi 08/2007; 87(32):2285-8.
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Wei-min Li,
Yue Li,
Ji-yi Zhao,
Ya-nan Duan, Li Sheng,
Bao-feng Yang,
Feng-long Wang,
Yong-tai Gong,
Shu-sen Yang,
Li-jun Zhou,
Pei-dong Liu,
Li Zhang,
Shan Chu
Chinese medical journal 05/2007; 120(7):598-600. · 0.86 Impact Factor
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Yue Li,
Wei-min Li,
Yong-tai Gong,
Bao-xin Li,
Wei Liu,
Wei Han,
Deli Dong, Li Sheng,
Jing-yi Xue,
Li Zhang,
Shan Chu,
Bao-feng Yang
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ABSTRACT: Owing to relative inefficacy and side effects of currently available antiarrhythmic drugs, current interest has shifted to treatments that target atrial fibrillation (AF) substrate. It has been suggested that calpain-induced atrial structural remodelling is under the control of renin-angiotensin system during AF. The purpose of this study is to investigate the effects of cilazapril and valsartan on the mRNA and protein expression of atrial calpains and atrial structural remodelling in AF dogs induced by chronic rapid atrial pacing. Twenty-seven dogs were randomly divided into sham-operated group (n = 6), control group (n = 7), cilazapril group (n = 7) and valsartan group (n = 7). One thin silicon plaque containing 4 pairs of electrodes was sutured to each atrium. A pacemaker was implanted in a subcutaneous pocket and attached to a screw-in epicardial lead in the right atrial appendage. The dogs in control group, cilazapril group and valsartan group were paced at 400 beats per minutes for 6 weeks. The dogs in cilazapril and valsartan groups received cilazapril (1mg x kg(-1)x d(-1)) or valsartan (30mg x kg(-1) x d(-1)) 1 week before rapid atrial pacing until pacing stop respectively. Transthoracic and transoesophageal echocardiographic examinations were performed in order to detect the changes of left atrium volume and contractile function. The inducibility and duration of AF were measured in all the groups. The expressions of atrial calpain I and calpain II mRNA were semi-quantified by reverse transcription-polymerase chain reaction. The protein levels of calpain I and calpain II in atrial myocardium were measured by Western-blot method. Pathohistological and ultrastructural changes in atrial tissue were tested by light and electron microscopy. Compared with the sham-operated control group, dramatic smaller left atrium and left atrial appendage volumes and significant higher atrial contractile function were observed in the cilazapril and valsartan groups. After 6-week atrial tachy-pacing, the mRNA and protein expressions of calpain I increased dramatically in the control group than that in the sham group, tissue calpain protein expression in all groups significantly correlated with the myolysis (r = 0.89, P < 0.01). Cilazapril and valsartan could significantly inhibit the gene and protein expressions of calpain I. No differences were found in the expression of calpain II mRNA and protein between the groups. Compared with atrial myocytes obtained from sham dogs, atrial myocytes from the control group dogs showed a reduced number of sarcomeres, a significant higher myolytic area of atria (24.3% vs. 3.1%, P < 0.01), increased vacuolization and dissolution. Cilazapril and valsartan could effectively prevent the pathohistological and ultrastructural changes induced by chronic rapid atrial pacing, dramatically decrease the area of myolysis (P < 0.05) and significantly reduce the inducibility and duration of AF. The expression of calpain I mRNA and protein increased remarkably in AF dogs. Cilazapril and valsartan can inhibit calpain I up-regulation, suppress atrial structural remodeling, and prevent the induction and promotion of AF in chronic rapid atrial pacing dogs.
Archiv für Kreislaufforschung 05/2007; 102(3):245-56. · 7.35 Impact Factor
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ABSTRACT: To study the relation of the structural remodeling processes and activation of calpain I.
Fifteen dogs were randomly divided into three groups. The dogs in pacing group (n=5) and inhibitor group (n=5) were subjected to 3 weeks of rapid atrial pacing at 600 beats/min, control dogs (n=5) were in sham-operated group. The dogs in inhibitor group were administered intravenous N-Acetyl-Leu-Leu-Met (ALLM), a calpain inhibitor, and in pacing group and sham-operated group were administered intravenous DMSO. The activity of calpain I was measured by hydrolyzing Suc-Leu-Leu-Val-Tyr-7-amino-4-methyl-coumarin. The ultrastructure of atrium was examined by light and electron microscopy. TnT expression was assessed by Western blot. Echocardiography examination was performed in all the three groups.
Calpain I activity was significantly increased in pacing group (2.3-fold, P<0.01), and decreased in inhibitor group (1.1-fold, P>0.05), compared to sham-operated group respectively. The percentages of myolysis were (76.7 +/- 5.9)% and (20.8 +/- 8.1)% in pacing group and inhibitor group respectively (P<0.01). TnT expression decreased in the rapid pacing-induced persistent atrial fibrillation, and these effects were inhibited by calpain I inhibitor ALLM. The area and volume of left atrium tended to increase after 3 weeks ALLM treatment in inhibitor group, but the change was not as prominent as in pacing group (P<0.05).
ALLM can decrease calpain I activity, and prevent canine atrial cardiomyocyte structural remodeling during atrial fibrillation. This study provided a capacity of atrial cardiomyocyte protection.
Zhonghua xin xue guan bing za zhi [Chinese journal of cardiovascular diseases] 02/2007; 35(2):132-6.
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ABSTRACT: The effects of angiotensin-converting enzyme inhibitor on long-term atrial electrophysiologic and structural remodeling are still unclear. The purpose of this study is to investigate the effects of Cilazapril on atrial electrical, structural, and functional remodeling in atrial fibrillation (AF) dogs induced by chronic rapid atrial pacing.
Twenty dogs were randomly divided into sham-operated group (n = 6), control group (n = 7), and Cilazapril group (n = 7). One thin silicon plaque containing 4 pairs of electrodes was sutured to each atrium. A pacemaker was implanted in a subcutaneous pocket and attached to a screw-in epicardial lead in the right atrial appendage. The dogs in control group and Cilazapril group were paced at 400 beats per minute for 6 weeks. The dogs in Cilazapril group received Cilazapril (0.5 mg x kg(-1) x d(-1)) 1 week before rapid atrial pacing until pacing stop. Before and after 6-week rapid atrial pacing, atrial effective refractory period (AERP) at 8 sites, AERP dispersion, intraatrium conduction time, inducibility, and duration of AF were measured. Transthoracic and transesophageal echocardiographic examinations included left atrium (LA) maximal volume, LA minimal volume, LA ejection fraction, left atrial appendage (LAA) maximal volume, LAA minimal volume, LAA ejection fraction, LAA maximal forward flow velocity, and LAA minimal backward flow velocity were performed. Atrial collagen volume fraction was analyzed by Masson staining.
After 6-week rapid atrial pacing, although there was no significant difference in AERP shortening and AERP rate adaptation reduction between the control group and the Cilazapril group, the inducibility and duration of AF were found to be dramatically lower in the Cilazapril group than those in the control group (AF inducibility, 65.7% vs 95.7%, P < .05; AF duration, 531.5 +/- 301.2 vs 1432.2 +/- 526.5 s, P < .01). The post-tachycardia intraatrium conduction times after 6 weeks with Cilazapril were significantly shorter than those in the control group. Cliazapril could partially prevent AERP dispersion increase induced by chronic rapid atrial pacing. Compared with the control group, the LA and LAA volumes were significantly smaller; LA ejection fraction, LAA ejection fraction, LAA maximal forward flow velocity, and LAA minimal backward flow velocity were dramatically higher in the Cilazapril group. The Cilazapril group had a significantly lower percentage of interstitial fibrosis than the control group.
Cilazapril can suppress structural and functional remodeling and prevent the induction and promotion of AF in chronic rapid atrial pacing dogs.
Journal of electrocardiology 02/2007; 40(1):100.e1-6. · 1.08 Impact Factor
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ABSTRACT: To examined the effect of local mild hypothermia on the expression of aquaporin-4 (AQP-4) following intracerebral hemorrhage (ICH) in rats and clarified the mechanism of hypothermia on brain edema formation following ICH.
Two hundreds and forty male Wistar rats were randomly divided into two groups: the intracerebral hemorrhage (ICH) group, in which autologous arterial blood were stereotaxically injected into right caudate nucleus; the local mild hypothermia (ICH + H) group, in which the rats were given 4 h local mild hypothermia after the injection of blood. Each group was divided into 6 subgroups: control, 6 h, 24 h, 72 h, 5 d and 7 d after operation; Brain water content was determined by dry-wet weight method and the permeability of BBB was measured by Evans-Blue extravasation. RT-PCR and Western blot were respectively used to evaluate AQP-4 mRNA and protein expression.
In ICH group, compared with control, ICH significantly increased BWC, the permeability of BBB and the expression of AQP-4 mRNA, all began at 6 h and peaked at 72 h (P < 0.01), the increased protein expression of AQP-4 began at 24 h and also peaked at 72 h (P < 0.01). AQP-4 expression positively correlated, both at the mRNA and the protein level, with the permeability of BBB (r = 0.78 and r = 0.76 respectively). In ICH + H group, compared with ICH group, the elevation of BWC, BBB permeability and AQP-4 protein expression were strongly attenuated at all time point by hypothermia treatment (P < 0.01), while AQP-4 mRNA levels demonstrated a modest attenuation from 48 h. At 72 h, AQP-4 mRNA optical density (A) decreased from 1.25 +/- 0.03 (ICH group) to 1.04 +/- 0.02 (P < 0.01), AQP-4 protein expression (A) decreased from 0.77 +/- 0.08 (ICH group) to 0.25 +/- 0.04 (P < 0.01).
This study indicates that BBB breakdown can increase the expression of AQP-4; local mild hypothermia can significantly reduce brain edema formation after ICH by suppressing the elevation of AQP-4 protein expression; Inhibition of BBB breakdown and the elevation of AQP-4 protein expression with local mild hypothermia appear to contribute to brain protection in this model.
Zhonghua yi xue za zhi 04/2006; 86(13):906-10.
