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Signal transduction mechanisms of isoproterenol induced myocardial hypertrophy
The 2nd Annual Scientific Meeting
033
•
JHFS
034
SIGNAL TRANSDUCTION MECHANISMS OF ISOPROTERENOL INDUCED MYOCARDIAL HYPERTROPHY
Estimation of cardiac hypertrophy in Goldblatt hypertensive rats by using echocardiography
YasuhikoTakemoto, Minoru Yoshiyama, Kazuhide Takeuchi, Takashi Omura, Hiroyuki Yamagishi, Iku Toda, Masakazu Teragaki, Kaname Akioka, Junichi Yoshikawa First Department of Internal Medicine, Osaka City UniversityMedical School, Osaka 545-005% Japan
Horikoshi K, Nagai M, Seki S, Onodera T, Arino T, Isiki M and Mochizuki S, Department of Jnternal Medicine 4, Jikei University, School of Medicine
The purpose of this study was to examine activator protein-1 (AP1) and nuclear factor-KB (NF-KB) DNA binding activity, which seem to be important in a signal transduction cascade upstream of the increased level of mRNA expression observed in isoproterenol-induced left ventricular hypertrophy. Rats were continuously infused with saline and low or high dose of isoproterenol (0.5 or 3 mg/kg/day) by an osmotic minipump for 12 hr, 24 hr, 48 hr or 72 hr.AP-1 and NF-KB DNA binding activity was determined using an electrophoretic mobility shift assay. Levels of ANP and c~-skeletal actin mRNAs were analyzed by Northern bJot hybridization. AP-1 DNA binding activities by low or high dose of [soproterenol administration were increased at 12 hr, reached their peak 24.1- and 37.1-fold (P<0.01) at 24 hr, and thereafter declined. Although N F-KB DNA binding activities by low dose of isoprotenol did not change, it by high dose increased to 6.0-fold (P<0.01) at 48 hr. Moreover, levels of ANP and c~skeletal actin mRNAs increased 8.0- and 3.5-fold (P<0.01) by low dose, and 14.3- and 6.2-fold (P<0.01) by high dose at 48 hr. Isoproterenol by high dose induced severe hypertrophy of myocyte and necrosis by histological examination. NF-KB DNA binding activities may be induced by an inflammatory response following myocardial injury. On the other hand, AP-1 DNA binding activity peaked at day1 in both low dose and high dose and levels of ANP and c~-skeltal actin mRNAs peaked at day 2. AP-1 DNA binding activity intially increased followed by increased expression of ANP and c~-skeletal actin mRNAs and these signal transduction mechasism may contribute to the isoproterenolinduced hypertrophy.
Aim: To estimate the degree of cardiac hypertrophy in animal model, echocardiographic study was performed in Goldblatt hypertensive rat. Method 1: Echocardiography was applied in Goldblatt rats at 3 and 5 weeks after an operation. All rats were sacrificed at 6 weeks and histological analysis was performed. Method 2: The angiotensin converting enzyme inhibitor, perindopdl, was administrated to Goldblatt rats from 1 weeks after an operation. Left ventdcular hypertrophy was estimated by echocardiography at 1, 2 and 3 weeks after an administration. Finally, histological study was analyzed to confirm the effect of perindopdl. Result: Interventdcular septum (IVSd, IVSs) was significantly increased in Goldblatt rats, while, left ventricular internal dimension (LVIDd, LVIDs) was decreased . Fractional shortening (FS) showed high value in Goldblatt rats than in non-treated rats (table). Histological study supported these echocardiographic findings. Perindopril was reduced blood pressure in Goldblatt rat, and reduction of cardiac hypertrophy was observed in the echocardiography. Discussion: Progression of cardiac hypertrophy and the effect of perindopril administration were observed in the echocardiography. IVSd IVSs LVIDd LVlDs
035 Tyrosine Phosphorylation is Associated with Enhanced Vascular Smooth Muscle Contractile Responses in Cardiomyopathic Hamsters Atsushi Sato, Mitsuhiro Fukao, Ichiro Sakuma*, Yuichi Hattori Morio Kanno, Akira Kitabatake* Department of Pharmacology and Department of Cardiovascular Medicine*, Hokkaido University School of Medicine We have previously observed that vascular smooth muscle contractile responses to phenylephrine, angiotensin II, and high K+were mark-
Control 1.82+-0.45 3.06+0.31 6.54±0.69 331 +-0.41 Goldblatt 2.44±0.40* 4.06±0.63" 4.66+1.08~ 1.34±0.61~ LVPWd LVPWs FS HW/BW Control 2.53±0.01 3.24±0.19 51.2±1.90 3.05+-0.21 Goldblatt 2.80±0.73 3.81--+0.01 73.9--+7.80*** 5.gO--+0.80"** *p
036 CARDIOPROTECTION DYSTROPHY
FOR
DUCHENNE
MUSCULAR
Yuka Ishikawa ~, John R Bach 2, Yukitoshi Ishikawa ~, Hitoko Ogata3, Ryoji Minami ~, ~Department of Pediatrics, National Yakumo Hospital, Hokkaido 049-3116, Japan, 2Department of Physical Medicine and Rehabilitation, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103-2406, USA, 3Department of Internal Medicine, Sapporo Shakaihoken general hospital, Sapporo 0040052, Japan
edly enhanced in cardiomyopathic hamsters (CM) compared with normal ones (FIB). In this study, we examed whether the tyrosine phosphorylation is associated with the enhanced vascular smooth muscle contractile responses to phenytephrine in CM. The thoracic aortas were removed from hamsters and changes in isometric force were recorded. Then, mesenteric arteries from hamsters were permeabilized by [3-escin (50 [aM) and isometric tension was measured. The aortic smooth muscle contractile responses to phenylephrine (l nM-30 [aM) was significantry enhanced in CM. Genistein (100 [aM), a tyrosine kinase inhibitor, inhibited this contractile responses to phenylephrine only in CM. In the absence of phenylephrine and GTR the Ca2+sensitivity of permeabilized mesenteric smooth muscle in CM was significantly enhanced compared with F] B (p<0.05). This Ca 2+sensitivity was further enhanced in the presence of phenylephrine (1 [aM) and GTP (10 [aM ) in CM. Moreover, this enhancement induced by phenylephrine and GTP in CM was significantly (p<0.001) inhibited by genistein (100 [aM). Thus, the enhanced smooth muscle contractile responses to agonists in CM may be mediated by tyrosine phosphorylation, which leads to the enhancement of Caz÷sensitivity.
Objectives: We study effectiveness of treatment for patients with congestive heart failure (CHF) due to dilated cardiomyopathy (DCM) secondary to Duchenne muscular dystrophy (DMD). Background: Once mechanical ventilation opened new option for treatment of these patients, death from heart failure is now a major concern. Design/Methods: 11 patients with DMD were compatible with DCM on echocardiogram and showed symptoms and neurohormanal activation which should be CHF (NYHA 3&4). They were started therapy with angiotensin-converting enzyme inhibitor (ACEI) in addition to digoxin and diuretics. After 1-9 months therapy with ACEI, beta-blocker was added. Duration of therapy was 9-62 months (ave. 32.5) with ACEI and 7-60 months (ave. 31.8) with beta blocker. Results: 2 of them died of CHF at 44 months and at 23 months. Atrial natriuretic peptide (ANP) were increased after 2 months of therapy with beta blocker but returned to lower level. Brain natriuretic pepfide (BNP) were once decreased with ACEI and keep lower level compared with one before treatment except neurohormanal re-activation in 2 patient just before death. After 28 months of beta blocker therapy, elevated plasma norepinephrine (PNE) were decreased once. Left ventricular end-diastolic dimension (LVDd) were well preserved in long-term therapy. Conclusions: Further study will be necessary to start treatment for DCM due to DMD with elevated BNP to prevent CHF.
73
033
•
JHFS
034
SIGNAL TRANSDUCTION MECHANISMS OF ISOPROTERENOL INDUCED MYOCARDIAL HYPERTROPHY
Estimation of cardiac hypertrophy in Goldblatt hypertensive rats by using echocardiography
YasuhikoTakemoto, Minoru Yoshiyama, Kazuhide Takeuchi, Takashi Omura, Hiroyuki Yamagishi, Iku Toda, Masakazu Teragaki, Kaname Akioka, Junichi Yoshikawa First Department of Internal Medicine, Osaka City UniversityMedical School, Osaka 545-005% Japan
Horikoshi K, Nagai M, Seki S, Onodera T, Arino T, Isiki M and Mochizuki S, Department of Jnternal Medicine 4, Jikei University, School of Medicine
The purpose of this study was to examine activator protein-1 (AP1) and nuclear factor-KB (NF-KB) DNA binding activity, which seem to be important in a signal transduction cascade upstream of the increased level of mRNA expression observed in isoproterenol-induced left ventricular hypertrophy. Rats were continuously infused with saline and low or high dose of isoproterenol (0.5 or 3 mg/kg/day) by an osmotic minipump for 12 hr, 24 hr, 48 hr or 72 hr.AP-1 and NF-KB DNA binding activity was determined using an electrophoretic mobility shift assay. Levels of ANP and c~-skeletal actin mRNAs were analyzed by Northern bJot hybridization. AP-1 DNA binding activities by low or high dose of [soproterenol administration were increased at 12 hr, reached their peak 24.1- and 37.1-fold (P<0.01) at 24 hr, and thereafter declined. Although N F-KB DNA binding activities by low dose of isoprotenol did not change, it by high dose increased to 6.0-fold (P<0.01) at 48 hr. Moreover, levels of ANP and c~skeletal actin mRNAs increased 8.0- and 3.5-fold (P<0.01) by low dose, and 14.3- and 6.2-fold (P<0.01) by high dose at 48 hr. Isoproterenol by high dose induced severe hypertrophy of myocyte and necrosis by histological examination. NF-KB DNA binding activities may be induced by an inflammatory response following myocardial injury. On the other hand, AP-1 DNA binding activity peaked at day1 in both low dose and high dose and levels of ANP and c~-skeltal actin mRNAs peaked at day 2. AP-1 DNA binding activity intially increased followed by increased expression of ANP and c~-skeletal actin mRNAs and these signal transduction mechasism may contribute to the isoproterenolinduced hypertrophy.
Aim: To estimate the degree of cardiac hypertrophy in animal model, echocardiographic study was performed in Goldblatt hypertensive rat. Method 1: Echocardiography was applied in Goldblatt rats at 3 and 5 weeks after an operation. All rats were sacrificed at 6 weeks and histological analysis was performed. Method 2: The angiotensin converting enzyme inhibitor, perindopdl, was administrated to Goldblatt rats from 1 weeks after an operation. Left ventdcular hypertrophy was estimated by echocardiography at 1, 2 and 3 weeks after an administration. Finally, histological study was analyzed to confirm the effect of perindopdl. Result: Interventdcular septum (IVSd, IVSs) was significantly increased in Goldblatt rats, while, left ventricular internal dimension (LVIDd, LVIDs) was decreased . Fractional shortening (FS) showed high value in Goldblatt rats than in non-treated rats (table). Histological study supported these echocardiographic findings. Perindopril was reduced blood pressure in Goldblatt rat, and reduction of cardiac hypertrophy was observed in the echocardiography. Discussion: Progression of cardiac hypertrophy and the effect of perindopril administration were observed in the echocardiography. IVSd IVSs LVIDd LVlDs
035 Tyrosine Phosphorylation is Associated with Enhanced Vascular Smooth Muscle Contractile Responses in Cardiomyopathic Hamsters Atsushi Sato, Mitsuhiro Fukao, Ichiro Sakuma*, Yuichi Hattori Morio Kanno, Akira Kitabatake* Department of Pharmacology and Department of Cardiovascular Medicine*, Hokkaido University School of Medicine We have previously observed that vascular smooth muscle contractile responses to phenylephrine, angiotensin II, and high K+were mark-
Control 1.82+-0.45 3.06+0.31 6.54±0.69 331 +-0.41 Goldblatt 2.44±0.40* 4.06±0.63" 4.66+1.08~ 1.34±0.61~ LVPWd LVPWs FS HW/BW Control 2.53±0.01 3.24±0.19 51.2±1.90 3.05+-0.21 Goldblatt 2.80±0.73 3.81--+0.01 73.9--+7.80*** 5.gO--+0.80"** *p
036 CARDIOPROTECTION DYSTROPHY
FOR
DUCHENNE
MUSCULAR
Yuka Ishikawa ~, John R Bach 2, Yukitoshi Ishikawa ~, Hitoko Ogata3, Ryoji Minami ~, ~Department of Pediatrics, National Yakumo Hospital, Hokkaido 049-3116, Japan, 2Department of Physical Medicine and Rehabilitation, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103-2406, USA, 3Department of Internal Medicine, Sapporo Shakaihoken general hospital, Sapporo 0040052, Japan
edly enhanced in cardiomyopathic hamsters (CM) compared with normal ones (FIB). In this study, we examed whether the tyrosine phosphorylation is associated with the enhanced vascular smooth muscle contractile responses to phenytephrine in CM. The thoracic aortas were removed from hamsters and changes in isometric force were recorded. Then, mesenteric arteries from hamsters were permeabilized by [3-escin (50 [aM) and isometric tension was measured. The aortic smooth muscle contractile responses to phenylephrine (l nM-30 [aM) was significantry enhanced in CM. Genistein (100 [aM), a tyrosine kinase inhibitor, inhibited this contractile responses to phenylephrine only in CM. In the absence of phenylephrine and GTR the Ca2+sensitivity of permeabilized mesenteric smooth muscle in CM was significantly enhanced compared with F] B (p<0.05). This Ca 2+sensitivity was further enhanced in the presence of phenylephrine (1 [aM) and GTP (10 [aM ) in CM. Moreover, this enhancement induced by phenylephrine and GTP in CM was significantly (p<0.001) inhibited by genistein (100 [aM). Thus, the enhanced smooth muscle contractile responses to agonists in CM may be mediated by tyrosine phosphorylation, which leads to the enhancement of Caz÷sensitivity.
Objectives: We study effectiveness of treatment for patients with congestive heart failure (CHF) due to dilated cardiomyopathy (DCM) secondary to Duchenne muscular dystrophy (DMD). Background: Once mechanical ventilation opened new option for treatment of these patients, death from heart failure is now a major concern. Design/Methods: 11 patients with DMD were compatible with DCM on echocardiogram and showed symptoms and neurohormanal activation which should be CHF (NYHA 3&4). They were started therapy with angiotensin-converting enzyme inhibitor (ACEI) in addition to digoxin and diuretics. After 1-9 months therapy with ACEI, beta-blocker was added. Duration of therapy was 9-62 months (ave. 32.5) with ACEI and 7-60 months (ave. 31.8) with beta blocker. Results: 2 of them died of CHF at 44 months and at 23 months. Atrial natriuretic peptide (ANP) were increased after 2 months of therapy with beta blocker but returned to lower level. Brain natriuretic pepfide (BNP) were once decreased with ACEI and keep lower level compared with one before treatment except neurohormanal re-activation in 2 patient just before death. After 28 months of beta blocker therapy, elevated plasma norepinephrine (PNE) were decreased once. Left ventricular end-diastolic dimension (LVDd) were well preserved in long-term therapy. Conclusions: Further study will be necessary to start treatment for DCM due to DMD with elevated BNP to prevent CHF.
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