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Role of oxidative stress in left ventricular remodeling and heart failure after myocardial infarction
The 3rd Annual Scientific Meeting
P-105
•
JHFS
P-106
LEFT VENTRICULAR REMODELING AND CHRONIC HEART FAILURE AFTER MYOCARDIAL INFARCTION IN MICE
ROLE OF OXIDATIVE STRESS IN LEFT VENTRICULAR REMODELING AND HEART FAILURE AFTER MYOCARDIAL INFARCTION
Akiu Koh, MD; Akira Matsumeri, MD,PhD; Yutaka Furukawa,MD, PhD; Koh One, MD, PhD; Masaharu Okada, MD; Atsushi Iwasaki, MD; Shigetake Sasayama, MD, PhD
Shintaro Kinugawa, Hiroyuki Tsutsui, Tomomi Ide, Hideo Ustumi, Nobuhiro Suematsu, Akira Takeshita Research Institute of Angiocardiology, Kyushu University, Fukuoka 812-8582, Japan
Department of Cardiovascular Medicine, Kyoto University 54 Kawaracho Shegoin, Sakyo-ku, Kyoto 606, Japan
The remodeling process after myocardial infarction (MI) leads to progressive left ventricular (LV) dilatation, impaired cardiac performance and clinical heart failure (HF). Experimental studies have suggested that antioxidant enzymes are decreased in the non-infarcted myocardium (NIM). However, the role of oxidative stress in this remodeling process remains unknown. This study was aimed to determine whether the production of reactive oxygen species (ROS) is enhanced in NIM and whether the administration of antioxidant to the animals is beneficial on LV remodeling. Anterior MI was produced in male CD-1 mice with a ligation of the left anterior descending coronary artery, which were divided into 2 treatment groups after 6 hrs of operation; dimethyithiourea (DMTU; 50mg/kg BW/day ip), hydroxyl radical scavenger, and vehicle for 4 weeks. We quantified the amount of ROS in the snap frozen NIM using electron spin resonance with 4-hydroxy-2,2,6,6,-tetramethylpiperidine-l-oxyl (hydroxy-TEMPO). ROS production, indexed by the decay rate of hydrexy-TEMPO (min-1), was significantly increased in MI-vehicle mice (0.059_+0.004 vs 0.080_+0.005), which was completely abolished by DMTU (0.059_+0.006). DMTU did not affect infarct size (60_+4 vs 56_+4%), but prevented the development of HF in association with the inhibition of LV dilatation, myocyte hypertrophy and interstitial fibrosis of NIM (table). In conclusion, oxidative stress plays a direct causative role in the development and progression of HF and LV remodeling after MI.
Today, various kinds of knock out or transgenic murine models enabled us to extend our murine research. This study was designed to establish the murine model of LV remodeling and heart failure after myocardial infarction. We induced myocardial infarction in 197, 8 to 9 weeks old male C57BL/6 mice. 24 hours, 3 days, and 1,2, 4, 8, 12, and 20 weeks after operation, groups of 4 or 5 mice each underwent echocardiographic study and were then sacrificed. Total heart, wet and dry lung weights were measured. Interstitial collagen deposition level were histologically measured using a computerized morphometdc system. The infarction area involved 57% of the left ventricle (LV) on average, and the mortality rate within 24 hours after operation was 53%. 17 out of 65 mice died of cardiac rupture within 8 days of coronary occlusion. Left ventricular end-diastolic diameter (LVEDd) increased from 3.4_+0.14 mm to 7.1_+0.59 mm (p<0.O01). Total heart and lung weights increased from 101+10 mg to 237_+34 mg (p<0.001), and from 147_+9.1 mg to 419-+55 mg, respectively (p<0.001). The wet/dry lung weight ratio increased from 4.49_+0.87 to 9.29_+0.31 (p<0.001). Volume collagen fraction increased from 0.64_+0.27% to 9.38_+0.63%. (p<0.001) In this murine model, the increase of wet/dry lung weight ratio was consistent with the development of chronic heart failure. It represents a promising experimental tool to study the molecular and biochemical mechanisms of LV remodeling and heart failure.
P-107
LVEDP
Lung wt/BW LV dimention Wall thickness (mm) (mm) 3.2_+0.1 0,52_+0.03 5.4_+2.3 5.2_+1.0 3 . 3 _ + 0 . 2 0,55_+0.05 18.4-+7.6. 10.2_+1.7. 4.3_+0.2* 0.76_+0.07* 5.9_+0.9~ 5.5_+0.4t 3,6+_0.2t 0.58_+0.02t
Group (mmHg) (mg/g) Sham+vehicle 3.7_+1.3 5.3_+0.4 Sham+ DMTU Ml+vehicle MI+DMTU
% Fibrosis
2.5_+0.3 2.8_+0.4 8.2_+1.0. 4.2-+1.3t
*p<0.05 vs Sham+vehicle, tp<0.05 vs Ml+vehicle
P-108
INCREASED CHYMASE IMMUNOREACTIVE CELLS AND T LYMPHOCYTES IN THE SUBEPICARDIUM OF THE INFARCTED MYOCARDIUM IN HUMAN
CHARACTERISTICS OF INTERVAL-FORCE RELATIONSHIP OF THE HEART DURING ATRIAL FIBRILLATION IN PATIENTS WITH CHRONIC HEART FAILURE
Fumihiro Hoshino, Hidenori Urata, Makoto Ihara, Yoshinari Uehara, Suguru Nakayama, Kazuyuki Shirai, Yoshihiro Tuchiya, Munehito Ideishi, Kikuo Arakawa Fukuoka University, Fukuoka 801-1011 ,Japan
Satoru Hirono, Makoto Kodama, Kiminod Kate, Masahiro Ire, Koichi Fuse, Yoshifusa Aizawa First Department of Internal Medicine, Niigata University School of Medicine, Niigata 951-8501, Japan
A number of evidences suggests that human chymase, a potent and specific angiotensin II-forming serine protease, is involved in tissue remodeling of cardiovascular diseases. In this study, tissue localization of chymase positive cells were determined in human myocardial infarction. Autopsied hearts post acute myocardial infarction (AMI)(n=8, 3 to 90days post-AMI) or without AMI (n=9) were used. Left ventricular tissues were cut at the level of papillary muscles through the short axis and the circular ventricular tissue was divided into 8 segments. Four pm sections of each segment wereimmunohistochemically stained for chymase, tryptase, cathepsin G, macrophage, and T lymphocytes. Positive cell number was counted under 200-fold magnification and were expressed as number/cm2. In the early stage of AMI (3 to 21days post AMI,n=5), the densities of chymase- and cathepsin G-positive cells in the myocardium were significantly higher than those in controls (882_+ 368 vs. 249_+96/cm2 and 1232--+482 vs. 407_+127/cm2, respectively). The density of tryptase-positive cells in the myocardium of early stage post-AMI patients tended to be higher than that in controls (299___179 vs. 66-+16/cm2 p<0.1). Majority of chymasepositive cells in post-AMI hearts were located in the subepicardium. Macrophage density increased in the necrotic lesion, while T lymphocytes increased mainly in the subepicardium of the infarcted segment, but did not increase in the same area of the non-infarcted segment. These cellular changes in post-AMI were not obvious in the late stage of post-AMI (30 to 90days post-AMI). This is the first report to show that the increased chymase immunopositive cells and T lymphocytes are mainly localized in the subepicardial region of the infarcted myocardium. These response in the epicardium may be important for the post-AMI remodeling.
Altered intracellular Ca2+handling dedved from sarcoplasmic reticulum (SR) dysfunction is thought to play an important role in the pathogenesis of myocardial functional abnormalities in heart failure. However, suitable method for clinical evaluation of Cardiac SR function has not yet been established. Because the interval-force relationship provides important clues to an understanding of Cardiac Ca~÷handling, we studied the interval-force relationship of the heart on a beat-to-beat basis during atdal fibrillation in 25 patients with chronic heart failure undergoing diagnostic Cardiac catheterization. The peak positive dP/dt (dP/dtm,~) was measured dudng 200 consecutive beats with a Cathetertip micromanometer introduced into the left ventdcle, and was plotted against pre-preceding and preceding RR intervals determined from a surface electrocardiogram. An inverse relation was found between dP/dtm~, and pre-preceding RR interval, indicating the presence of post-extrasystolic potentiation. When those beats of which prepreceding RR interval was less than 800ms were excluded, a significantly positive curvilinear relationship between dP/dtma,and preceding RR interval became evident. In all 25 patients, the relationship could be fitted to a monoexponential curve typical of mechanical restitution with a specific time constant. The time constant was inversely related to left ventricular ejection fraction (P<0.01), and was significantly higher in patients with NYHA class III (421_-t~262ms) compared with class I and II (160+89 and 284+143ms, P<0.05). Since mechanical restitution kinetics is found to be slow in failing heart, a longer preceding RR interval would be required to achieve maximal contractile response, with less contractile reserve at a higher heart rate. Mechanical restitution is in vivo measures of cardiac Ca2÷ handling and may provide physiological correlates of SR function.
79
P-105
•
JHFS
P-106
LEFT VENTRICULAR REMODELING AND CHRONIC HEART FAILURE AFTER MYOCARDIAL INFARCTION IN MICE
ROLE OF OXIDATIVE STRESS IN LEFT VENTRICULAR REMODELING AND HEART FAILURE AFTER MYOCARDIAL INFARCTION
Akiu Koh, MD; Akira Matsumeri, MD,PhD; Yutaka Furukawa,MD, PhD; Koh One, MD, PhD; Masaharu Okada, MD; Atsushi Iwasaki, MD; Shigetake Sasayama, MD, PhD
Shintaro Kinugawa, Hiroyuki Tsutsui, Tomomi Ide, Hideo Ustumi, Nobuhiro Suematsu, Akira Takeshita Research Institute of Angiocardiology, Kyushu University, Fukuoka 812-8582, Japan
Department of Cardiovascular Medicine, Kyoto University 54 Kawaracho Shegoin, Sakyo-ku, Kyoto 606, Japan
The remodeling process after myocardial infarction (MI) leads to progressive left ventricular (LV) dilatation, impaired cardiac performance and clinical heart failure (HF). Experimental studies have suggested that antioxidant enzymes are decreased in the non-infarcted myocardium (NIM). However, the role of oxidative stress in this remodeling process remains unknown. This study was aimed to determine whether the production of reactive oxygen species (ROS) is enhanced in NIM and whether the administration of antioxidant to the animals is beneficial on LV remodeling. Anterior MI was produced in male CD-1 mice with a ligation of the left anterior descending coronary artery, which were divided into 2 treatment groups after 6 hrs of operation; dimethyithiourea (DMTU; 50mg/kg BW/day ip), hydroxyl radical scavenger, and vehicle for 4 weeks. We quantified the amount of ROS in the snap frozen NIM using electron spin resonance with 4-hydroxy-2,2,6,6,-tetramethylpiperidine-l-oxyl (hydroxy-TEMPO). ROS production, indexed by the decay rate of hydrexy-TEMPO (min-1), was significantly increased in MI-vehicle mice (0.059_+0.004 vs 0.080_+0.005), which was completely abolished by DMTU (0.059_+0.006). DMTU did not affect infarct size (60_+4 vs 56_+4%), but prevented the development of HF in association with the inhibition of LV dilatation, myocyte hypertrophy and interstitial fibrosis of NIM (table). In conclusion, oxidative stress plays a direct causative role in the development and progression of HF and LV remodeling after MI.
Today, various kinds of knock out or transgenic murine models enabled us to extend our murine research. This study was designed to establish the murine model of LV remodeling and heart failure after myocardial infarction. We induced myocardial infarction in 197, 8 to 9 weeks old male C57BL/6 mice. 24 hours, 3 days, and 1,2, 4, 8, 12, and 20 weeks after operation, groups of 4 or 5 mice each underwent echocardiographic study and were then sacrificed. Total heart, wet and dry lung weights were measured. Interstitial collagen deposition level were histologically measured using a computerized morphometdc system. The infarction area involved 57% of the left ventricle (LV) on average, and the mortality rate within 24 hours after operation was 53%. 17 out of 65 mice died of cardiac rupture within 8 days of coronary occlusion. Left ventricular end-diastolic diameter (LVEDd) increased from 3.4_+0.14 mm to 7.1_+0.59 mm (p<0.O01). Total heart and lung weights increased from 101+10 mg to 237_+34 mg (p<0.001), and from 147_+9.1 mg to 419-+55 mg, respectively (p<0.001). The wet/dry lung weight ratio increased from 4.49_+0.87 to 9.29_+0.31 (p<0.001). Volume collagen fraction increased from 0.64_+0.27% to 9.38_+0.63%. (p<0.001) In this murine model, the increase of wet/dry lung weight ratio was consistent with the development of chronic heart failure. It represents a promising experimental tool to study the molecular and biochemical mechanisms of LV remodeling and heart failure.
P-107
LVEDP
Lung wt/BW LV dimention Wall thickness (mm) (mm) 3.2_+0.1 0,52_+0.03 5.4_+2.3 5.2_+1.0 3 . 3 _ + 0 . 2 0,55_+0.05 18.4-+7.6. 10.2_+1.7. 4.3_+0.2* 0.76_+0.07* 5.9_+0.9~ 5.5_+0.4t 3,6+_0.2t 0.58_+0.02t
Group (mmHg) (mg/g) Sham+vehicle 3.7_+1.3 5.3_+0.4 Sham+ DMTU Ml+vehicle MI+DMTU
% Fibrosis
2.5_+0.3 2.8_+0.4 8.2_+1.0. 4.2-+1.3t
*p<0.05 vs Sham+vehicle, tp<0.05 vs Ml+vehicle
P-108
INCREASED CHYMASE IMMUNOREACTIVE CELLS AND T LYMPHOCYTES IN THE SUBEPICARDIUM OF THE INFARCTED MYOCARDIUM IN HUMAN
CHARACTERISTICS OF INTERVAL-FORCE RELATIONSHIP OF THE HEART DURING ATRIAL FIBRILLATION IN PATIENTS WITH CHRONIC HEART FAILURE
Fumihiro Hoshino, Hidenori Urata, Makoto Ihara, Yoshinari Uehara, Suguru Nakayama, Kazuyuki Shirai, Yoshihiro Tuchiya, Munehito Ideishi, Kikuo Arakawa Fukuoka University, Fukuoka 801-1011 ,Japan
Satoru Hirono, Makoto Kodama, Kiminod Kate, Masahiro Ire, Koichi Fuse, Yoshifusa Aizawa First Department of Internal Medicine, Niigata University School of Medicine, Niigata 951-8501, Japan
A number of evidences suggests that human chymase, a potent and specific angiotensin II-forming serine protease, is involved in tissue remodeling of cardiovascular diseases. In this study, tissue localization of chymase positive cells were determined in human myocardial infarction. Autopsied hearts post acute myocardial infarction (AMI)(n=8, 3 to 90days post-AMI) or without AMI (n=9) were used. Left ventricular tissues were cut at the level of papillary muscles through the short axis and the circular ventricular tissue was divided into 8 segments. Four pm sections of each segment wereimmunohistochemically stained for chymase, tryptase, cathepsin G, macrophage, and T lymphocytes. Positive cell number was counted under 200-fold magnification and were expressed as number/cm2. In the early stage of AMI (3 to 21days post AMI,n=5), the densities of chymase- and cathepsin G-positive cells in the myocardium were significantly higher than those in controls (882_+ 368 vs. 249_+96/cm2 and 1232--+482 vs. 407_+127/cm2, respectively). The density of tryptase-positive cells in the myocardium of early stage post-AMI patients tended to be higher than that in controls (299___179 vs. 66-+16/cm2 p<0.1). Majority of chymasepositive cells in post-AMI hearts were located in the subepicardium. Macrophage density increased in the necrotic lesion, while T lymphocytes increased mainly in the subepicardium of the infarcted segment, but did not increase in the same area of the non-infarcted segment. These cellular changes in post-AMI were not obvious in the late stage of post-AMI (30 to 90days post-AMI). This is the first report to show that the increased chymase immunopositive cells and T lymphocytes are mainly localized in the subepicardial region of the infarcted myocardium. These response in the epicardium may be important for the post-AMI remodeling.
Altered intracellular Ca2+handling dedved from sarcoplasmic reticulum (SR) dysfunction is thought to play an important role in the pathogenesis of myocardial functional abnormalities in heart failure. However, suitable method for clinical evaluation of Cardiac SR function has not yet been established. Because the interval-force relationship provides important clues to an understanding of Cardiac Ca~÷handling, we studied the interval-force relationship of the heart on a beat-to-beat basis during atdal fibrillation in 25 patients with chronic heart failure undergoing diagnostic Cardiac catheterization. The peak positive dP/dt (dP/dtm,~) was measured dudng 200 consecutive beats with a Cathetertip micromanometer introduced into the left ventdcle, and was plotted against pre-preceding and preceding RR intervals determined from a surface electrocardiogram. An inverse relation was found between dP/dtm~, and pre-preceding RR interval, indicating the presence of post-extrasystolic potentiation. When those beats of which prepreceding RR interval was less than 800ms were excluded, a significantly positive curvilinear relationship between dP/dtma,and preceding RR interval became evident. In all 25 patients, the relationship could be fitted to a monoexponential curve typical of mechanical restitution with a specific time constant. The time constant was inversely related to left ventricular ejection fraction (P<0.01), and was significantly higher in patients with NYHA class III (421_-t~262ms) compared with class I and II (160+89 and 284+143ms, P<0.05). Since mechanical restitution kinetics is found to be slow in failing heart, a longer preceding RR interval would be required to achieve maximal contractile response, with less contractile reserve at a higher heart rate. Mechanical restitution is in vivo measures of cardiac Ca2÷ handling and may provide physiological correlates of SR function.
79