Yoshiyuki Furuse

Uric Acid-Lowering Treatment With Benzbromarone in Patients With Heart Failure A Double-Blind Placebo-Controlled Crossover Preliminary Study

Background— Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results— Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P <0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide ( P <0.01), and creatinine levels ( P =0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA ( P <0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 μU/mL; benzbromarone, 11.0±6.2 μU/mL; P <0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P <0.05), and tumor necrosis factor-α (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P <0.05) improved after benzbromarone, and the changes in tumor necrosis factor-α levels were correlated with reduction of SUA ( P <0.05). Conclusions— These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration— clinical trials.gov. Identifier: [NCT00422318][1]. Received March 26, 2009; accepted November 3, 2009. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00422318&atom=%2Fcirchf%2F3%2F1%2F73.atomBackground—Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results—Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 &mgr;U/mL; benzbromarone, 11.0±6.2 &mgr;U/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P<0.05), and tumor necrosis factor-&agr; (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-&agr; levels were correlated with reduction of SUA (P<0.05). Conclusions—These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration—clinicaltrials.gov. Identifier: NCT00422318.

Uric Acid-Lowering Treatment With Benzbromarone in Patients With Heart FailureCLINICAL PERSPECTIVE

Background— Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results— Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P <0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide ( P <0.01), and creatinine levels ( P =0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA ( P <0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 μU/mL; benzbromarone, 11.0±6.2 μU/mL; P <0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P <0.05), and tumor necrosis factor-α (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P <0.05) improved after benzbromarone, and the changes in tumor necrosis factor-α levels were correlated with reduction of SUA ( P <0.05). Conclusions— These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration— clinical trials.gov. Identifier: [NCT00422318][1]. Received March 26, 2009; accepted November 3, 2009. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00422318&atom=%2Fcirchf%2F3%2F1%2F73.atomBackground—Hyperuricemia is common in chronic heart failure (CHF), and it is a strong independent marker of prognosis. Upregulated xanthine oxidase (XO) activity and impaired renal excretion have been shown to account for increased serum uric acid (UA) levels in CHF. Therapeutic interventions with allopurinol to reduce UA levels by XO inhibition have been shown to be beneficial. Discussions are ongoing whether UA itself is actively involved or it is a mere marker of upregulated XO activity within CHF pathophysiology. Therefore, the aim of this study was to test the effect of lowering UA by uricosuric treatment without XO inhibition on hemodynamic and metabolic characteristics of CHF. Impaired renal excretion of UA was taken into account. Methods and Results—Serum UA (SUA), urinary UA (uUA) excretion, and renal clearance test for UA (ClUA) were measured in 82 patients with CHF. SUA was significantly increased compared with controls of similar age (control, 5.45±0.70 mg/dL; New York Heart Association I, 6.48±1.70 mg/dL; New York Heart Association II, 7.34±1.94 mg/dL; New York Heart Association III, 7.61±2.11 mg/dL; P<0.01). Patients with CHF showed lower uUA excretion and ClUA. On multivariate analysis, insulin, brain natriuretic peptide (P<0.01), and creatinine levels (P=0.05) showed independent correlation with SUA. The treatment effect of the uricosuric agent benzbromarone was tested in 14 patients with CHF with hyperuricemia in a double-blind, placebo-controlled, randomized crossover study design. Benzbromarone significantly decreased SUA (P<0.01). Brain natriuretic peptide, left ventricular ejection fraction, and dimensions in echocardiographic assessment did not change after benzbromarone therapy. In contrast, fasting insulin (placebo, 18.8±8.9 &mgr;U/mL; benzbromarone, 11.0±6.2 &mgr;U/mL; P<0.05), homeostasis model assessment of insulin resistance index (placebo, 5.4±2.6; benzbromarone, 3.0±1.7; P<0.05), and tumor necrosis factor-&agr; (placebo, 2.59±0.63 pg/mL; benzbromarone, 2.14±0.51 pg/mL; P<0.05) improved after benzbromarone, and the changes in tumor necrosis factor-&agr; levels were correlated with reduction of SUA (P<0.05). Conclusions—These results show that UA lowering without XO inhibition may not have an effect on hemodynamic impairment in CHF pathophysiology. To the extent that these data are correct, this finding suggests that upregulated XO activity rather than UA itself is actively involved in hemodynamic impairment in CHF. Clinical Trial Registration—clinicaltrials.gov. Identifier: NCT00422318.

Ammonia Response To Constant Exercise: Differences To The Lactate Response

1. We evaluated the plasma ammonia response to constant exercise at different intensities. Ten healthy male volunteers were asked to perform constant exercise for 15 min at five different intensities: 80, 90, 100, 110 and 120% of their ventilatory threshold (VT). Blood concentrations of lactate, ammonia and hypoxanthine were measured during and after exercise.

The release of the substrate for xanthine oxidase in hypertensive patients was suppressed by angiotensin converting enzyme inhibitors and alpha1-blockers.

Objective Hyperuricemia is associated with the vascular injury of hypertension, and purine oxidation may play a pivotal role in this association, but the pathophysiology is not fully understood. We tested the hypothesis that in hypertensive patients, the excess amount of the purine metabolite, hypoxanthine, derived from skeletal muscles, would be oxidized by xanthine oxidase, leading to myogenic hyperuricemia as well as to impaired vascular resistance caused by oxygen radicals. Methods We investigated the production of hypoxanthione, the precursor of uric acid and substrate for xanthine oxidase, in hypertensive patients and found that skeletal muscles produced hypoxanthine in excess. We used the semi-ischemic forearm test to examine the release of hypoxanthine (ΔHX), ammonium (ΔAmm) and lactate (ΔLAC) from skeletal muscles in essential hypertensive patients before (UHT:n = 88) and after treatment with antihypertensive agents (THT:n = 37) in comparison to normotensive subjects (NT:n = 14). Results ΔHX, as well as ΔAmm and ΔLAC, were significantly higher in UHT and THT (P < 0.01) than in NT. This release of ΔHX from exercising skeletal muscles correlated significantly with the elevation of lactate in NT, UHT and THT (y = 0.209 + 0.031 x;R2 = 0.222, n = 139:P < 0.01). Administration of doxazosin (n = 4), bevantolol (n = 5) and alacepil (n = 8) for 1 month significantly suppressed the ratio of percentage changes in ΔHX by − 38.4 ± 55.3%, − 51.3 ± 47.3% and − 76.3 ± 52.2%, respectively (P < 0.05) but losartan (n = 3), atenolol (n = 7) and manidipine (n = 10) did not reduce the ratio of changes; on the contrary, they increased it in ΔHX by +188.2 ± 331%, +96.2 ± 192.2% and +42.6 ± 137.3%, respectively. The elevation of ΔHX after exercise correlated significantly with the serum concentration of uric acid at rest in untreated hypertensive patients (y = 0.194 − 0.255x;R2 = 0.185, n = 30:P < 0.05). The prevalence of reduction of both ΔHX and serum uric acid was significantly higher in the patients treated with alacepril, bevantolol and doxazosin (67%:P < 0.02) than in the patients treated with losartan, atenolol and manidipine (12%). Conclusions It is concluded that the skeletal muscles of hypertensive patients released ΔHX in excess by activation of muscle-type adenosine monophosphate (AMP) deaminase, depending on the degree of hypoxia. The modification of ΔHX by angiotensin-converting enzyme inhibitors and α1-blockers influenced the level of serum uric acid, suggesting that the skeletal muscles may be an important source of uric acid as well as of the substrate of xanthine oxidase in hypertension.

Effects of Spironolactone on Exercise Capacity and Neurohormonal Factors in Patients with Heart Failure Treated with Loop Diuretics and Angiotensin-Converting Enzyme Inhibitor

1. Treatment with spironolactone is reported to be useful when combined with loop diuretics and an angiotensin-converting enzyme (ACE) inhibitor in severe congestive heart failure (CHF). However, the effects of the addition of spironolactone on exercise capacity and neurohormonal variables have not been demonstrated. This study determined the effects of additive spironolactone on exercise capacity and neurohormonal factors in patients with mild CHF. 2. Oxygen uptake (VO2), plasma norepinephrine (NE), renin activity (PRA), angiotensin II (AII), aldosterone (ALD), and atrial natriuretic peptide (ANP) were measured at rest and after peak exercise in nine patients with CHF (six idiopathic and three ischemic cardiomyopathy; New York Heart Association (NYHA) classes II and III) who were already taking furosemide (mean 29 +/- 5 mg/day) and enalapril (mean 4.7 +/- 0.8 mg/day). Studies were repeated after 16 weeks of treatment with additive single daily dose of 25 mg of spironolactone. In four of nine patients, the exercise test was repeated after a 4-weeks washout of spironolactone. 3. Treatment with spironolactone caused natriuresis, decreased cardiothoracic ratio in chest X-ray (before vs. after treatment: 53.7 +/- 1.2 vs. 50.7 +/- 1.4%, P < 0.01), and improved NYHA functional class. Peak VO2 (17.1 +/- 1.6 vs. 17.5 +/- 2.2 ml/min/kg, NS) and heart rate and blood pressure responses to exercise were not altered. Resting NE (215 +/- 41 vs. 492 +/- 85 pg/ml, P < 0.01) and resting PRA (8.2 +/- 2.3 vs. 16.2 +/- 4.1 ng/ml/hr, P < 0.01) as well as peak NE (1618 +/- 313 vs. 2712 +/- 374 pg/ml, P < 0.01) and peak PRA (12.8 +/- 3.2 vs. 28.1 +/- 11.8 ng/ml/hr, P = 0.17) were augmented after additive spironolactone. ALD and AII were insignificantly increased, and ANP was insignificantly decreased at peak exercise after spironolactone treatment. Spironolactone washout was associated with a trend of the neurohormones to return toward pretreatment values. 4. In conclusion, chronic additive treatment with spironolactone was associated with neurohormonal activation both at rest and during exercise without changing the exercise capacity of patients with mild CHF who were already on loop diuretics and ACE inhibitor therapy.

Signaling pathway and chronotropic action of parathyroid hormone in isolated perfused rat heart.

Parathyroid hormone (PTH) activates both adenylyl cyclase and phospholipase C via the PTH-1 receptor. We previously reported that PTH increased heart rate and that this effect was mediated via the pacemaker current (I f ). However, it has been reported that PTH exerts its chronotropic effect via an interaction with adrenergic receptors or via L-type calcium channels. Thus, the objective of the study was to elucidate the exact mechanism of the chronotropic effect of PTH. We tested whether its chronotropic effects could be abolished by inhibitors of the following systems in isolated perfused rat hearts: &agr;-adrenergic (prazosin); &bgr;-adrenergic (propranolol); angiotensin II (CV11974); endothelin-1 (TAK044); calcium channel (verapamil); adenylyl cyclase (miconazole); phospholipase C (U73122) or I f (CsCl). In addition, we measured the cyclic adenosine monophosphate level of the heart after PTH administration. Whereas prazosin, propranolol, CV11974, TAK044, verapamil, and U73122 did not inhibit the chronotropic effect of PTH, CsCl or miconazole suppressed it significantly. PTH increased the cyclic adenosine monophosphate level of the atrium but not the left ventricle. These results indicate that the chronotropic actions of PTH are mediated via selective activation of adenylyl cyclase to increase the I f current.

Ca2+‐sensitizing effect is involved in the positive inotropic effect of troglitazone

Troglitazone, an insulin sensitizing agent, has a direct positive inotropic effect. However, the mechanism of this effect remains unclear. Thus, we examined the inotropic effect of troglitazone while focusing on intracellular Ca2+ handling. Troglitazone significantly increased peak isovolumic left ventricular pressure (LVPmax), peak rate of rise of LVP (dP/dtmax), peak rate of fall of LVP (dP/dtmin) in isolated rat hearts perfused at a constant coronary flow and heart rate. This inotropic effect of troglitazone was not inhibited by pretreatment with carbachol (muscarine receptor agonist), H89 (protein kinase A inhibitor), U73122 (phospholipase C inhibitor), H7 (protein kinase C inhibitor), verapamil (L‐type Ca2+ channel antagonist), thapsigargin (Ca2+‐adenosine triphosphatase inhibitor) or ryanodine (ryanodine receptor opener). Radioimmunoassay showed that the cyclic adenosine monophosphate concentration in the left ventricle was not increased by troglitazone. Whole‐cell patch clamp analysis revealed that troglitazone had no effect on inward Ca2+ currents in cardiomyocytes. In fura‐2 loaded perfused rat hearts, troglitazone exerted its positive inotropic effect without increasing Ca2+ concentration. These results suggest that neither the inward Ca2+ currents nor Ca2+ handling in the sarcoplasmic reticulum was involved in the inotropic effect of troglitazone. Furthermore, troglitazone exerted its positive inotropic effect without affecting the intracellular concentration of Ca2+. In conclusion, the positive inotropic effect of troglitazone is mediated by a sensitization of Ca2+.

Analysis of moricizine block of sodium current in isolated guinea-pig atrial myocytes. Atrioventricular difference of moricizine block.

The effects of moricizine on Na+ channel currents (INa) were investigated in guinea-pig atrial myocytes and its effects on INa in ventricular myocytes and on cloned hH1 current were compared using the whole-cell, patch-clamp technique. Moricizine induced the tonic block of INa with the apparent dissociation constant (Kd,app) of 6.3 microM at -100 mV and 99.3 microM at -140 mV. Moricizine at 30 microM shifted the h infinity curve to the hyperpolarizing direction by 8.6 +/- 2.4 mV. Moricizine also produced the phasic block of INa, which was enhanced with the increase in the duration of train pulses, and was more prominent with a holding potential (HP) of -100 mV than with an HP of -140 mV. The onset block of INa induced by moricizine during depolarization to -20 mV was continuously increased with increasing the pulse duration, and was enhanced at the less negative HP. The slower component of recovery of the moricizine-induced INa block was relatively slow, with a time constant of 4.2 +/- 2.0 s at -100 mV and 3.0 +/- 1.2 s at -140 mV. Since moricizine induced the tonic block of ventricular INa with Kd,app of 3.1 +/- 0.8 microM at HP = -100 mV and 30.2 +/- 6.8 microM at HP = -140 mV, and cloned hH1 with Kd,app of 3.0 +/- 0.5 microM at HP = -100 mV and 22.0 +/- 3.2 microM at HP = -140 mV, respectively, either ventricular INa or cloned hH1 had significantly higher sensitivity to moricizine than atrial INa. The h infinity curve of ventricular INa was shifted by 10.5 +/- 3.5 mV by 3 microM moricizine and that of hH1 was shifted by 5.0 +/- 2.3 mV by 30 microM moricizine. From the modulated receptor theory, we have estimated the dissociation constants for the resting and inactivated state to be 99.3 and 1.2 microM in atrial myocytes, 30 and 0.17 microM in ventricular myocytes, and 22 and 0.2 microM in cloned hH1, respectively. We conclude that moricizine has a higher affinity for the inactivated Na+ channel than for the resting state channel in atrial myocytes, and moricizine showed the significant atrioventricular difference of moricizine block on INa. Moricizine would exert an antiarrhythmic action on atrial myocytes, as well as on ventricular myocytes, by blocking Na+ channels with a high affinity to the inactivated state and a slow dissociation kinetics.

Troglitazone Improves Cardiac Function in Patients with Congestive Heart Failure

Troglitazone increased cardiac output and stroke volume, as a result of decreased peripheral resistance, in diabetic patients with normal cardiac function. The cardiovascular effects of troglitazone in patients with heart failure are unknown. The aim of the study was to evaluate the cardiovascular effects of troglitazone in patients with heart failure.Blood pressure and echocardiographic findings were evaluated before and 1, 2, 3 and 4 hours after a single dose of troglitazone (400 mg) or placebo, in eight type II diabetic patients with congestive heart failure. The plasma catecholamines and coefficient of variance of RR intervals (CVRR) were also measured.Neither heart rate nor blood pressure changed after the administration of troglitazone. Left ventricular (LV) end-diastolic dimension did not change either, however, the LV end-systolic dimension significantly decreased compared with its baseline value and with that of the placebo group. On the other hand, the % fractional shortening and the E/A ratio increased significantly after troglitazone. The LV end-diastolic volume did not change, whereas the LV end-systolic volume significantly decreased. The stroke volume and the LV ejection fraction significantly increased compared with its baseline value and with that of the placebo group. The peripheral vascular resistance did not change after the administration of troglitazone, whereas plasma catecholamines significantly decreased, and CVRR remained unchanged in both groups.These hemodynamic changes suggest that a single oral dose of troglitazone induced inotropy without activation of the sympathetic nervous system.

AUGMENTED EXERCISE PLASMA NORADRENALINE WITH IMPAIRED CHRONOTROPIC RESPONSIVENESS IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

1. There is controversy regarding plasma catecholamine levels in patients with hypertrophic cardiomyopathy (HCM) and few data exist on serial plasma catecholamine measurements during exercise. The present study determined whether cardiovascular and plasma catecholamine responses to exercise were altered in patients with HCM.