Prognostic impact of supraventricular premature complexes in community-based health checkups: the Ibaraki Prefectural Health Study.

AIMS: The long-term prognosis of subjects with supraventricular premature complexes (SVPCs) remains unclear in the general population. The aim of this study was to examine the prognostic significance of SVPCs in community-based health checkups. METHODS AND RESULTS: We assessed 63 197 individuals (mean age, 58.8 ± 9.9 years; 67.6% women) who participated in annual community-based health checkups in 1993 and were followed until 2008. The primary endpoint was stroke death, cardiovascular death (CVD), or all-cause death during a 14-year mean follow-up, and the secondary endpoint was first atrial fibrillation (AF) event in subjects without self-reported heart diseases or AF at baseline. Compared with subjects without SVPCs, the multivariate-adjusted hazard ratios (HRs) [95% confidence interval (CI)] of stroke death, CVD, and all-cause death in subjects with SVPCs were 1.24 (0.98-1.56) for men and 1.63 (1.30-2.05) for women, 1.22 (1.04-1.44) for men and 1.48 (1.25-1.74) for women, and 1.08 (0.99-1.18) for men and 1.21 (1.09-1.34) for women, respectively. Atrial fibrillation occurred in 386 subjects during the follow-up (1.05/1000 person-years). The presence of SVPCs at baseline was the significant predictor of AF onset [HRs (95% CI): 4.87 (3.61-6.57) for men and 3.87 (2.69-5.57) for women]. Propensity score matched analyses also revealed the presence of SVPCs was significantly associated with increased risks of AF incidence and CVD even after adjusting the potential confounders. CONCLUSION: The presence of SVPCs in 12-lead electrocardiograms was a strong predictor of AF development, and associated with increased risk of CVD in general population.

An increase in right atrial magnetic strength is a novel predictor of recurrence of atrial fibrillation after radiofrequency catheter ablation.

BACKGROUND: Differences in electrical properties between left and right atria (LA and RA) after pulmonary vein isolation (PVI) for atrial fibrillation (AF) are currently poorly understood. Magnetocardiograms were used to investigate the effect of PVI on bi-atrial magnetic field changes and their relationship to clinical outcomes. METHODS AND RESULTS: This study included 71 patients undergoing PVI for paroxysmal AF. Magnetocardiograms were recorded at baseline and 1 day, 8 weeks, and 24 weeks after ablation. Peak magnitude of LA and RA segments on P waves was separately compared before and after PVI. During a 16-month post-ablation period, 53 (75%) patients were free from AF recurrences. LA magnetic strength in patients without recurrence persistently decreased for 24 weeks and was significantly lower at 8 weeks than that in patients with recurrence (1.28±0.69 vs. 1.74±0.71 pico-Tesla, P=0.02). RA magnetic strength in patients with recurrence persistently rose for 24 weeks and was significantly higher at 8 weeks than that in patients without recurrence (2.17±0.82 vs. 3.00±1.12 pico-Tesla, P=0.001). Multivariate analysis showed RA magnetic strength at 8 weeks to be the strongest predictor of AF recurrence (odds ratio=3.335; 95% confidence interval=1.181-9.416; P=0.02). CONCLUSIONS: PVI resulted in distinct changes in magnetic strength in both the LA and the RA. A persistent rise in RA magnetic strength might be a robust predictor of AF recurrence after ablation.

Repolarization spatial-time current abnormalities in patients with coronary heart disease.

BACKGROUND: Magnetocardiography (MCG) is a new technique for visualizing a current distribution in the myocardium. In recent years, current distribution parameters (CDPs) have been developed based on the distribution. The CDPs reflect spatial-time current abnormalities in patients with coronary heart disease (CHD). However, the criteria and scoring method of the abnormalities using CDPs are still controversial. METHOD: We measured MCG signals for 101 normal controls and 56 CHD patients (single-, double-, and triple-vessel diseases) using a MCG system. The CDPs (maximum current vector [MCV], total current vector [TCV], current integral map, and current rotation) during ventricular repolarization were analyzed. To evaluate the CDPs that are effective in distinguishing between normal controls and CHD patients, the areas under the receiver operating characteristic curve (A(z)) are calculated. Furthermore, the total scores ("0" to "4") of four CDPs with high A(z) values are also calculated. RESULTS: MCV and TCV angles at the T-wave peak had the highest A(z) value. Furthermore, TCV angular differences between the ST-T segment also had high A(z) values. Using the four CDPs, the averaged total score for patients with triple-vessel disease was the highest ("2.67") compared to the other groups (normal controls: 0.53). Furthermore, based on the assumption that subjects with a total score over "1" were suspected of having CHD, sensitivity and specificity were 85.7% and 74.3%, respectively. CONCLUSION: We concluded that the score and criteria using MCV and TCV during repolarization in CHD patients can reflect lesion areas and time changes of electrical activation dispersion due to ischemia.

Association of sleep-disordered breathing and ventricular arrhythmias in patients without heart failure.

The prevalence and characteristics of sleep-disordered breathing (SDB) in patients with ventricular arrhythmias, such as premature ventricular complexes and ventricular tachycardia, are unknown. Therefore, this study was conducted to evaluate the prevalence of SDB in patients with severe ventricular arrhythmias and normal left ventricular (LV) function. Thirty-five patients (63% men, mean age 57.4 +/- 13.8 years) underwent a sleep study. All patients had ventricular tachycardia or frequent premature ventricular complexes (>or=300/hour) and had been referred to the cardiology department for medication, catheter ablation therapy, or the implantation of a cardioverter-defibrillator. Patients with heart failure with LV ejection fractions <50% were excluded; in the remaining patients, the mean LV ejection fraction was 63.9 +/- 8.0%. Twenty-one patients (60%) had SDB with apnea-hypopnea indexes >or=5/hour, and the average apnea-hypopnea index was 22.7 +/- 17.9/hour. Twelve patients (34%) had moderate to severe SDB, with an average apnea-hypopnea index of 33.6 +/- 16.6/hour. Central dominant sleep apnea was evident in 3 patients with SDB. The average age and body mass index were significantly higher in patients with SDB than in those without SDB (age 62.0 +/- 12.8 vs 50.6 +/- 12.7 years, body mass index 26.3 +/- 4.0 vs 21.2 +/- 2.0 kg/m2). In conclusion, this study found a high prevalence of SDB in patients with ventricular arrhythmias and normal LV function.

Standard template of adult magnetocardiogram.

BACKGROUND: We need to know the magnetocardiogram (MCG) features regarding waveform and two-dimensional current distribution in normal subjects in order to classify the abnormal waveform in patients with heart disease. However, a standard MCG waveform has not been produced yet, therefore, we have first made the standard template MCG waveform. METHODS AND RESULTS: We used data from 464 normal control subjects' 64-channel MCGs (268 males, 196 females) to produce a template MCG waveform. The measured data were averaged after shortening or lengthening and normalization. The time interval and amplitude of the averaged data were adjusted to mean values obtained from a database. Furthermore, the current distributions (current arrow maps [CAMs]) were calculated from the produced templates to determine the current distribution pattern. The produced template of the QRS complex had a typical shape in six regions that we defined (M1, M2, M3, M4, M5, and M6). In the P wave, the main current arrow in CAMs pointing in a lower-left direction appeared in M1. In the QRS complex, the typical wave appeared in each region, and there were two main current arrows in M2 and M5. There were negative T waves in M1, M4, and M5, and positive T waves in M3 and M6, and the main current arrow pointing in a lower-left direction appeared in M2. CONCLUSION: Template MCG waveforms were produced. These morphologic features were classified into six regions, and the current distribution was characterized in each region. Consequently, the templates and classifications enable understanding MCG features and writing clinical reports.

Gender-associated differences in pharmacokinetics and anti-arrhythmic effects of flecainide in Japanese patients with supraventricular tachyarrhythmia.

OBJECTIVE: We examined the effect of gender-associated differences in pharmacokinetics on the anti-arrhythmic effects of flecainide in Japanese patients with supraventricular tachyarrhythmia and in healthy subjects. METHODS: The study population comprised 72 outpatients (52 males and 20 females) treated with oral flecainide for supraventricular tachyarrhythmias. Serum flecainide concentrations were determined by use of high-performance liquid chromatography. The anti-arrhythmic efficacy of flecainide was assessed for at least 2 months through evaluation of symptomatology, electrocardiograms, and Holter monitoring. Pharmacokinetics of flecainide after a single 50-mg dose was examined in 14 healthy subjects (7 males and 7 females). RESULTS: The daily dose of flecainide did not differ between males and females (2.87 +/- 0.68 versus 2.92 +/- 0.90 mg/kg). The serum flecainide concentration was significantly lower in males than in females (315 +/- 151 versus 408 +/- 184 ng/mL, P < 0.05). Clinically relevant efficacy of flecainide was achieved significantly (P < 0.05) less often in male patients (31 of 52; 60%) than in female patients (19 of 20; 95%). We confirmed that nonrenal clearance of flecainide among healthy subjects was significantly higher in males than in females (0.77 +/- 0.16 versus 0.57 +/- 0.06 L h(-1) kg(-1), P < 0.05). CONCLUSIONS: Our results suggest that the anti-arrhythmic efficacy of flecainide differed between males and females because of gender-associated differences in pharmacokinetics.

Down-regulated VEGF expression in the diabetic heart is normalized by an endothelin ETA receptor antagonist.

Recently, down-regulation of vascular endothelial growth factor (VEGF) in the heart was suggested as a potential molecular explanation for the increased risk of cardiovascular morbidity and mortality in patients with diabetes. Increased endothelin-1 production is reported in diabetes. Here, we report that down-regulated VEGF expression in the diabetic rat heart is normalized by an endothelin ETA receptor antagonist, suggesting that endothelin antagonism may be a novel therapeutic strategy for diabetic heart.

Effects of a selective endothelin a receptor antagonist on the expressions of iNOS and eNOS in the heart of early streptozotocin-induced diabetic rats.

Vascular tone is regulated through the actions of locally produced agents. Among the vasoconstrictors, the most potent agent is endothelin (ET), which exerts its vasoconstrictor actions principally through ET type A (ET(A)) receptors. Of the vasodilators, nitric oxide (NO) seems to be the most important contributor to the acute regulation of vascular tone. Vasculopathy is an important feature of diabetes mellitus (DM). Endogenous ET-mediated vasoconstrictor tone is augmented in diabetic states, and conflicting results persist concerning the NO system in diabetes. The present study investigated the expressions of inducible NO synthases (iNOS) and endothelial NOS (eNOS) in the heart of diabetic animals and the effects of a selective ET(A) receptor antagonist on these alterations. Type I diabetes was induced by intraperitoneal injection of streptozotocin (65 mg/kg) in Sprague-Dawley rats, while control (Con) rats received only citrate buffer. After 1 week, the streptozotocin-administered rats were randomly divided into two groups: the selective ET(A) receptor antagonist-administered group (DM+TA-0201, 1 mg/kg/day, by osmotic minipump for 2 weeks) and the DM+vehicle group (comprising the diabetic rats that received saline). The random blood glucose level was 405 +/- 103 mg/dl in DM animals, and this level was unchanged by ET antagonism. Body weight was more greatly decreased in DM rats than in Con rats, but the left ventricle to body weight ratio was increased in the DM group and was unaffected by ET antagonism. Protein expressions of eNOS and iNOS were assessed in the left ventricular tissues. eNOS expression was significantly increased in DM heart and was greatly inhibited by the treatment with ET antagonist. The expression of iNOS was also increased in early DM heart but was reversed by the ET antagonist. Thus, endothelin antagonism might be beneficial for DM heart by reversing the upregulated eNOS and iNOS expressions.

Changes in important apoptosis-related molecules in the endothelin-1-induced hypertrophied cardiomyocytes: effect of the pretreatment with eicosapentaenoic Acid.

Human heart failure is preceded by a process called cardiac remodeling, in which heart chambers progressively enlarge and contractile function deteriorates. Programmed cell death (apoptosis) of cardiac muscle cells has been identified as an essential process in the progression to heart failure. The execution of the apoptotic program entails complex interactions between and execution of multiple molecular subprograms. Endothelin (ET)-1, a potent vasoconstrictor peptide, is synthesized and secreted by cardiomyocytes and induces hypertrophy of cardiomyocytes. The cardiovascular benefit of fish oil containing eicosapentaenoic acid (EPA) in humans and experimental animals was reported. Recently, we found that ET-1-induced cardiomyocytic remodeling could be prevented by pretreatment with EPA. The aim of the present study is to investigate whether there would be any alteration in the expression of important apoptosis-related molecules in ET-1-administered hypertrophied cardiomyocytes. We also sought to determine, if there are alterations in apoptotic molecules, what type of role for EPA would then exist. Ventricular cardiomyocytes were isolated from 2-day-old Sprague-Dawley rats and were cultured for 3 days. At Day 4 of culture, the cardiomyocytes were divided into three groups: control, the ET-1 (0.1 nM)-treated group, and the ET-1 group pretreated with EPA (10 microM). Twenty-four hours after the treatment, the gene expressions of three important molecules related to apoptosis (caspase-3, Bax, and Bcl-2) in three experimental groups were evaluated by real-time polymerase chain reaction. The present study could not demonstrate any significant or representative alteration in any of the above three apoptosis-related important markers in either ET-1-induced hypertrophied cardiomyocytes with or without EPA pretreatment. The present study would at least be able to exclude the involvement of some representative molecules related to apoptosis in ET-1-induced hypertrophied cardiomyocytes. In addition, the present study demonstrates that the antihypertrophic effect of EPA to ET-1-administered cardiomyocytes appears not to modulate the apoptosis signaling cascade.

Endothelin antagonism suppresses plasma and cardiac endothelin-1 levels in SHRSPs at the typical hypertensive stage.

Endothelin-1 (ET-1) has been implicated in hypertension, heart failure, atherosclerosis, and pulmonary hypertension. In all these conditions, plasma immunoreactive ET-1 levels are elevated, and tissue ET-1 expression is increased. Clinical trials have demonstrated potentially important benefits of ET antagonism among patients with essential hypertension, pulmonary hypertension, and heart failure. It is unknown whether ET antagonism affects the production of ET-1 in stroke-prone spontaneously hypertensive rat (SHRSP) heart at the typical hypertensive stage. The objective of this study was to investigate the effects of ET blockade on the expression levels of plasma and cardiac ET-1 in SHRSPs. SHRSPs were treated for 3 months with SB209670 (ET(A)/ET(B) dual receptor antagonist) or with saline (vehicle) commencing at the prehypertensive stage (age 6 weeks). Plasma and left ventricular ET-1 peptide levels were measured using enzyme-linked immunoabsorbent assay. Compared with age-matched control Wistar-Kyoto rats, peptide levels of ET-1 were significantly upregulated in vehicle-treated SHRSP heart; this upregulation was reversed by long-term ET antagonism. Plasma ET-1 levels were also significantly increased in vehicle-treated SHRSPs and were normalized by ET antagonism. mRNA expression of preproET-1, which is the source of ET-1 peptide production, was significantly increased in vehicle-treated SHRSP heart and was normalized by ET antagonism. Marked cardiac hypertrophy and fibrosis at the histologic level in SHRSPs were ameliorated by ET antagonism, and left ventricular hypertrophy as seen on echocardiography in SHRSPs was suppressed by ET blockade. After ET antagonism, systolic blood pressures were reduced in SHRSPs; diastolic blood pressures were unchanged. The reversal effect of the upregulated ET system in SHRSP heart by ET antagonism might be independent of blood pressure change. By suppressing the upregulated ET system, ET antagonism might be beneficial in arresting cardiac remodeling.

Alterations in gene expressions encoding preproET-1 and NOS in pulmonary tissue in endotoxemic rats.

Septic shock is characterized by hypotension and a hyporeactive response to vasopressor agents. The pathogenesis is due to vascular leaks and an increased synthesis of cytokines and nitric oxide (NO). The present study examined the time-dependent alterations of endothelin-1 (ET-1) and the expression of NO synthase (NOS) in lung tissue in a septic rat model. Normal Sprague-Dawley (SD) rats aged 10 weeks received 15 mg/kg lipopolysaccharide (LPS) and then were sacrificed at different time points (1, 3, 6, and 10 hrs). Rats that did not receive LPS were considered to be controls. Both systolic and diastolic pressure decreased in SD rats after LPS administration. Time-dependent onset of features of acute lung injury, such as the infiltration of inflammatory cells and thickening of alveolar septa, were seen in rats that received LPS. A 2.8-fold increase in the expression of preproET-1 level was observed in lung tissue 6 hrs after LPS administration. The expression of endothelial NOS (eNOS) was also altered in lung tissue in a time-dependent fashion. After the administration of LPS, there was a 16-fold increase in the expression of eNOS mRNA. The peak expression of inducible NOS (iNOS) in lung tissue specimens obtained from rats that received LPS was 45-fold higher than that in control rats. ET-1 is a potent vasoconstrictor and thereby may play an important role in the pathogenesis of acute lung injury in a septic rat model. The increased expression of NOS may result in excess NO production and may also play a role in the pulmonary complications of endotoxemia.

Effects of dual endothelin receptor antagonist on antiapoptotic marker Bcl-2 expression in streptozotocin-induced diabetic rats.

Erectile dysfunction (ED) affects approximately 50% of male patients with diabetes mellitus (DM) and is possibly due to the vascular and neuropathic complications of DM. Recently, apoptosis has been regarded as a downstream event in ED. More recently, the importance of alterations in apoptosis-related molecules in the mechanism of DM-induced ED has begun to be appreciated. Endothelin-1 (ET-1) plays a role via ET(A) and ET(B) receptors in the regulation of cavernosal smooth-muscle tone in penile tissues. We found that the ET-1 level in the penis of rats with DM was higher than that in the penis of control animals. The present study investigated a rat model in which DM was induced by a 3-week regimen of streptozotocin (STZ) to assess the expression of several apoptosis-related molecules in penile tissue and, concomitantly, the effects of ET antagonism on these changes. Male Sprague-Dawley rats (weight [+/-SD], 450 +/- 26 g) received a citrate saline vehicle or STZ (65 mg/kg ip). DM was confirmed by the presence of hyperglycemia. Diabetic animals were further separated into two treatment groups 1 week after onset of disease: one group received ET(A/B) dual receptor antagonist (SB209670) by means of osmotic minipump at a dosage of 1 mg/day, and the other group received saline. Rats in both groups were treated for 2 weeks and then sacrificed. Plasma glucose levels (+/-SD) in rats with DM were significantly higher than those in rats without DM (506 +/- 70 vs. 111 +/- 11 mg/dl). In the penile tissue of rats with DM, a 35% decrease in the expression of Bcl-2 protein (an important antiapoptotic marker detectable by immunoblotting) was seen, and ET(A/B) dual antagonist was observed to significantly counteract this decrease. Real-time polymerase chain reaction revealed that the expression of Bcl-2 mRNA was consistent with Bcl-2 protein expression. Levels of Bax and caspase-3, two important proapoptotic markers, were not significantly altered in the present study. Thus, we conclude that, in the penis of rats with early stage DM, the protection against apoptosis has decreased but can be improved by ET antagonism.

Alterations of gene expressions of preproET-1 and ET receptors in brains of endotoxemic Sprague-Dawley rats.

During severe sepsis, several immunological defense mechanisms initiate a cascade of inflammatory events leading to multiorgan failure, including septic encephalopathy and ultimately death. Endothelin-1 (ET-1) has recently been investigated in different cerebral pathologies. Some reports suggest the involvement of ET-1 in sepsis. However, no study to date has reported the alterations in expression of the genes encoding preproET-1 and ET receptors in the frontal cortex of the septic brain. Male Sprague-Dawley (SD) rats 8 weeks of age were administered either saline or 15 mg/kg lipopolysaccharide (LPS) at different time points (1, 3, 6, and 10 hrs). Rats that did not receive LPS were considered to be controls. The rats were sacrificed with ether, and the brain tissues were harvested. Systolic and diastolic blood pressure decreased 1 hr after LPS administration and then gradually returned to normal, without any change in the heart rate. We confirmed the induction of endotoxemia in the brains of SD rats by measuring the expression of nitric oxide synthase (NOS) mRNA induced in the cerebrum. The expression of inducible NOS (iNOS) mRNA in the brains of SD rat after LPS administration was 30-fold higher than that in the brains of control rats. mRNA expression of preproET-1 in the frontal cortex of SD rats after LPS administration was 2-fold higher than that in control rats. A time-dependent increase in the expression of the gene encoding the ET(A) receptor (vasoconstrictive property) after LPS administration was observed in SD rat brain, whereas expression of the gene encoding the ET(B) receptor (vasodilatatory property) showed an initial upregulation and then gradually decreased as sepsis progressed. In conclusion, we report for the first time that expressions of the genes encoding ET-1 and ET receptors are altered in the endotoxemic brain and that these alterations are time-dependent in SD rats. The alterations in the ET system in brain tissue observed in the present study may contribute to the understanding of the pathophysiological changes in the endotoxemic brain.

Effect of eicosapentaenoic acid on the different endothelin system components in endothelin-1-induced hypertrophied cardiomyocytes.

The cardiovascular benefit of fish oil, including eicosapentaenoic acid (EPA), in humans and experimental animals has been reported. The role of endothelin-1 (ET-1) in cardiac hypertrophy is well known. Endothelin-1 stimulates prepro-ET-1 mRNA expression in cardiomyocytes, and the autocrine/paracrine system of ET-1 is important for cardiomyocyte hypertrophy. Although many studies link EPA to cardiac protection, the effect of EPA on cardiac hypertrophy has yet to be clarified. Recently, we demonstrated that ET-1-induced cardiomyocytic change could be prevented by pretreatment with EPA. The present study investigated the changes of different components of the ET system at the mRNA level in ET-1-administered cardiomyocytes, and examined the effect of EPA pretreatment. Ventricular cardiomyocytes were isolated from 2-day-old Sprague-Dawley rats, cultured in Dulbecco's modified Eagle's medium and Ham F12 supplemented with 0.1% fatty acid-free bovine serum albumin for 3 days. At Day 4 of culture, the cardiomyocytes were divided into 3 groups: control group, ET-1-treated (0.1 nM) group, and ET-1-treated group pretreated with EPA (10 microM). Twenty-four hours after treatment, the gene expressions of different components of the endothelin system in three experimental groups were evaluated by real-time polymerase chain reaction. Prepro-ET-1 mRNA expression was 53% upregulated in ET-1-induced hypertrophied cardiomyocytes and suppressed in the EPA-pretreated group. Endothelin-converting enzyme-1 (ECE-1) was also increased in ET-1-administered cardiomyocytes by 42% compared with the control group and was reversed in the EPA-pretreated group. The two receptors of ET system, ET(A) and ET(B), tended to be increased in the ET-1-treated group, but no statistical significance was seen among study groups. Endothelin-1 increased prepro-ET-1 and ECE-1 mRNA expression in hypertrophied-neonatal cardiomyocytes, and this was reversed with EPA pretreatment. Thus, EPA may play a crucial role in the regression of ET-1-induced cardiomyocyte hypertrophy, partly through the suppression of ET-1 and ECE-1 expression.

Differential effects of selective endothelin type a receptor antagonist on the gene expression of vascular endothelial growth factor and its receptors in streptozotocin-induced diabetic heart.

Cardiovascular complications are an important feature of diabetes mellitus (DM). Abnormal and decreased coronary collateral development has been implicated in the pathogenesis of cardiac complications in DM. More recently, decreased expression of vascular endothelial growth factor (VEGF) and its receptors has been found in diabetic heart. To our knowledge, no study has focused on the therapeutic improvement associated with VEGF in diabetic heart. DM was induced by intraperitoneal injection of streptozotocin (65 mg/kg) in Sprague-Dawley rats, while control rats received only citrate buffer. After 1 week, the streptozotocin-treated rats were randomly divided into two groups: one group received the selective endothelin (ET) type A receptor antagonist TA-0201 at a dose of 1 mg/kg/day for 2 weeks by osmotic mini-pump, and the vehicle group received saline only. The plasma glucose level was 504 +/- 75 mg/dl in the diabetic rats and was unchanged by treatment with ET antagonist. The body weight was decreased in the diabetic rats compared with the control rats, but the left ventricular (LV)-body weight ratio was increased in the diabetic group and was unaffected by treatment with ET antagonist. mRNA expression of VEGF and its receptors (Flt-1 and Flk-1) in the LV tissues was assessed using real-time polymerase chain reaction. VEGF expression was significantly decreased in diabetic heart and was greatly improved by treatment with ET antagonist. The expression of VEGF receptors was down-regulated in early diabetic heart but was not recovered by treatment with ET antagonist. ET and its receptor A might have differential regulation on the gene expressions of VEGF and its receptors in early diabetic heart.

EPA effect on NOS gene expression and on NO level in endothelin-1-induced hypertrophied cardiomyocytes.

Cardiomyocytes release (or metabolize) several diffusible agents (e.g., nitric oxide [NO], endothelin-1 [ET-1], and angiotensin II) that exert direct effects on myocyte function under various pathologic conditions. Although cardiac hypertrophy is a compensatory mechanism in response to different cardiovascular diseases, there can be a pathologic transition in which the myocardium becomes dysfunctional. Recently, NO has been found to be an important regulator of cardiac remodeling. Specifically, NO has been recognized as a potent antihypertrophic and proapoptotic mediator in cultured cardiomyocytes. We demonstrated that ET-1-induced hypertrophic remodeling in neonatal cardiomyocytes was arrested by pretreatment with eicosapentaenoic acid (EPA), a major component of fish oil. In some recent studies, EPA has demonstrated cardioprotective effects by modulating NO. This study investigated the changes in NO synthase (NOS) in ET-1-induced hypertrophied cardiomyocytes and in total levels of nitrates and nitrites. Ventricular cardiomyocytes were isolated from 2-day-old Sprague-Dawley rats and were cultured in D-MEM/Ham F12 supplemented with 0.1% fatty acid-free bovine serum albumin for 3 days. At Day 4 of culture, the cardiomyocytes were divided into three groups: control group, ET-1 (0.1 nM) group, and ET-1 pretreated with EPA (10 microM) group. NOS gene expression was evaluated 24 hrs after treatment using real-time polymerase chain reaction. Endothelial NOS (eNOS) mRNA expression was decreased in the ET-1 group compared with controls and was unchanged by pretreatment with EPA. mRNA expression of inducible NOS (iNOS) was significantly increased in ET-1-treated cardiomyocytes and was suppressed by EPA pretreatment. Neuronal NOS gene expression and total NO level did not exhibit a statistically significant change in any of the groups. There may be some interaction between ET-1, eNOS, and iNOS in ET-1-induced and EPA-regressed hypertrophied cardiomyocytes that suppress iNOS expression without modulating total NO level or eNOS gene expression.

Altered expression of endothelin, vascular endothelial growth factor, and its receptor in hepatic tissue in endotoxemic rat.

Sepsis involves a heterogeneous class of syndromes, and septic shock, a severe form of sepsis, is associated with the development of progressive damage in multiple organs. The present study examined the time-dependent alterations of endothelin-1 (ET-1) and vascular endothelial growth factor (VEGF) levels in liver tissue in a septic rat model. Healthy male Wistar rats aged 15 weeks received 15 mg/kg lipopolysaccharide (LPS) and were sacrificed at different time points (1, 3, 6, and 10 hrs after treatment). Rats that did not receive LPS were considered to be controls. A 28-fold increase in the ET-1 level was observed in liver tissue 10 hrs after LPS administration. VEGF was also altered in hepatic tissue in a time-dependent manner. A gradual increase of VEGF expression in liver tissue after LPS administration was observed. Expression of Flt-1, the vascular permeability receptor of VEGF, was also increased in liver tissue after LPS administration. ET-1 is a potent vasoconstrictor and, therefore, may play a role in the regulation of hepatic perfusion in a sepsis model. On the other hand, VEGF may be involved in capillary leakage in liver tissue after LPS administration. The present findings suggest that there might be a loss of balance between the ET-1 and VEGF levels in the septic liver at different time points, which could contribute to the pathogenesis of acute liver injury in endotoxemia.

[Magnetocardiographic diagnosis for myocardial ischemia and arrhythmias].

Magnetocardiography (MCG) is a non-invasive and non-contact mapping technique to analyze cardiac electromagnetic activities. The SQUID (superconducting quantum interference device) system has made it possible to detect very weak cardiac magnetic signals noninvasively. In electrocardiography (ECG), the conductivity of electric current varies according to body composition, while in MCG, conductivity of magnetic field is constant regardless of body composition. Moreover, as the magnetic field detected in MCG originates not from the cardiac 'volume current' as in ECG, but from the cardiac 'primary current', the cardiac electromagnetic information of the MCG is minimally distorted. Furthermore, ECG is a record of a potential difference, so it gives only a relative value, while magnetic field strength is an absolute value. Therefore, MCG is expected to be more sensitive to minute electromagnetic abnormalities of heart disease than ECG. In this article, we discuss the usefulness of MCG in diagnosing ischemic heart diseases and arrhythmias.

Vascular endothelin-B receptor system in vivo plays a favorable inhibitory role in vascular remodeling after injury revealed by endothelin-B receptor-knockout mice.

BACKGROUND: Two subtypes of endothelin (ET) receptors, ET(A) and ET(B), are distributed in vascular smooth muscle cells to cause contraction and proliferation. Vascular endothelial cells express only ET(B) receptors, which cause NO release. Although ET(A) receptor blockade is reported to be effective in ameliorating vascular remodeling, there is no report on the long-term effect of ET(B) receptor blockade on vascular remodeling after injury. METHODS AND RESULTS: ET(B) receptor-knockout (KO) mice, which were genetically rescued from lethal intestinal aganglionosis, and wild-type (WT) mice underwent complete ligation of the right common carotid artery, ie, a blood flow cessation model of vascular remodeling. Fourteen days after ligation, the intimal area, the ratio of intimal to medial areas, and the stenotic ratio in the ligated artery of KO mice were significantly increased compared with those of WT mice. The expression level of ET-1 mRNA in the ligated artery of KO mice was increased similarly to that of WT mice, whereas tissue NO(x) levels in lesions of KO mice were significantly lower than those of WT mice. Long-term treatment with the ET(A) receptor antagonist TA-0201 (0.5 mg x kg(-1) x d(-1)) significantly ameliorated vascular stenosis in both groups. Long-term treatment with the ET(B) receptor antagonist A-192621 (30 mg x kg(-1) x d(-1)) worsened vascular remodeling in WT mice. CONCLUSIONS: We demonstrated that inhibition of the ET(B) receptor system is harmful for vascular remodeling after injury, the mechanism of which is partly attributed to decreased NO release, in KO mice. These results suggest that the overall effect of vascular ET(B) receptors is antiproliferative in the injured artery.

Involvement of endogenous endothelin-1 in exercise-induced redistribution of tissue blood flow: an endothelin receptor antagonist reduces the redistribution.

BACKGROUND: Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor peptide. Exercise results in a significant redistribution of tissue blood flow, which greatly increases blood flow in active muscles but decreases it in the splanchnic circulation. We reported that exercise causes an increase of ET-1 production in the internal organ and then hypothesized that ET-1 participates in the exercise-induced redistribution of tissue blood flow. We investigated the effects of acute endothelin-A (ETA)-receptor blockade on regional tissue blood flow during exercise in rats. METHODS AND RESULTS: Regional blood flow in the kidney, spleen, stomach, intestine, and muscles was measured using the microsphere technique before and during treadmill running of 30 minutes duration at 30 m/min after pretreatment with either an ETA-receptor antagonist (TA-0201; 0.5 mg/kg) or vehicle in rats. Blood flow in the kidney, spleen, stomach, and intestine was decreased by exercise, but the magnitude of the decrease after pretreatment with TA-0201 was significantly smaller than that after pretreatment with vehicle. Furthermore, the increase in blood flow to active muscles induced by exercise was significantly smaller in rats pretreated with TA-0201 than those pretreated with vehicle. CONCLUSIONS: The present study revealed that ET-1-mediated vasoconstriction participates in the decrease of blood flow in the internal organs of rats during exercise, and therefore, that these actions of endogenous ET-1 partly contribute to the increase of blood flow in active muscles during exercise. The data suggest that endogenous ET-1 participates in the exercise-induced redistribution of tissue blood flow.