Junkichi Hama

Short-Acting Nifedipine and Diltiazem Do Not Reduce the Incidence of Cardiac Events in Patients With Healed Myocardial Infarction

BACKGROUND The administration of calcium antagonists to patients with healed myocardial infarction is a controversial treatment. This study was conducted to elucidate the effect of short-acting nifedipine and diltiazem on cardiac events in patients with healed myocardial infarction. METHODS AND RESULTS A controlled clinical open trial of 1115 patients with healed myocardial infarction was carried out between 1986 and 1994. The patients included 595 who received no calcium antagonist, 341 who received short-acting nifedipine 30 mg/d, and 179 who received short-acting diltiazem 90 mg/d. The primary end points were cardiac events, which were defined as fatal or nonfatal recurrent myocardial infarction; death from congestive heart failure; sudden death; and hospitalization because of worsening angina, congestive heart failure, or premature ventricular contractions. Cardiac events occurred in 51 patients (8.6%) in the no-calcium-antagonist group and 54 (10.4%) in the calcium-antagonist group (odds ratio, 1.24; 95% CI, 0.83 to 1.85), demonstrating that the calcium antagonists did not reduce the incidence of cardiac events. Subgroup analysis revealed no beneficial effects of these drugs for reducing cardiac events in patients with such complications as hypertension or angina pectoris. CONCLUSIONS This study showed that use of short-acting nifedipine and diltiazem in this postmyocardial infarction population was associated with a 24% higher cardiac event rate, but this strong adverse trend did not reach statistical significance.

Atrial Natriuretic Peptide and Antihypertensive Action Due to β-Blockade in Essential Hypertensive Patients

The effects of β-blocker treatment on hemodynamics were studied in relation to plasma atrial natriuretic peptide (ANP) levels in 17 outpatients with essential hypertension. Administration of propranolol for twelve weeks to untreated subjects resulted in a signif icant (P < 0.001) rise in plasma ANP levels (from 37.9 ±21.2 to 66.7 ±46.2 pg/mL, mean ±SD). Systolic and diastolic blood pressures were significantly decreased (P < 0.05 and P < 0.01, respectively). Heart rate was also significantly decreased (P < 0.001). On the other hand, a significant reduction of cardiac index was detected (from 4.12 ±1.34 to 2.96 ±0.75 L/min/m2, P < 0.01) with chronic administration of propranolol, suggesting a reflection of decreased cardiac function. A significant negative correlation was observed between %changes in systolic blood pressure and %changes in plasma ANP (r=-0.594, P < 0.05). These results suggest that the increased plasma ANP levels may contribute to the antihypertensive effect with propranolol.

Regulation of aldosterone receptor in rat kidney cytosol by atrial natriuretic factor.

We investigated the effect of atrial natriuretic factor (ANF) on aldosterone receptors in the kidney cytosol, because the binding of aldosterone to aldosterone receptors in the cytosol is considered a critical step of its action. Rat atriopeptin III was injected into male Sprague-Dawley rats (200-250 g) via the femoral vein while under pentobarbital anesthesia, and aldosterone receptors in the kidney cytosol were determined. The maximum binding capacity and dissociation constant were calculated by the Scatchard analysis. Maximum binding capacity of both types of aldosterone receptor (Type I, high affinity and low binding capacity and Type II, low affinity and high binding capacity) gradually decreased after ANF injection, reached the lowest level after 2 hours, and then slightly recovered. When more than 2.5 micrograms/kg of rat atriopeptin III was injected, the density of aldosterone receptors significantly decreased. Injection of 12.5 micrograms/kg of rat atriopeptin III decreased maximum binding capacity of Type I receptor from 42.3 +/- 2.4 (mean +/- SD, n = 6) to 22.8 +/- 3.2 femtomole/mg protein (n = 6) (p less than 0.01), and that of Type II receptor decreased from 388 +/- 46 to 285 +/- 30 fmol/mg protein (p less than 0.01). Dissociation constant of both types of receptors did not change significantly after ANF injection. Plasma aldosterone concentration showed no significant change after ANF injection, and a significant change was noted after ANF administration on aldosterone receptors in the experiments on adrenalectomized rats 7 days after operation. Furosemide had no significant effect on aldosterone receptors in both normal and adrenalectomized rats.(ABSTRACT TRUNCATED AT 250 WORDS)

EFFECT OF AN ANGIOTENSIN II RECEPTOR ANTAGONIST, TCV‐116, ON NEOINTIMAL FORMATION FOLLOWING BALLOON INJURY IN THE SHR CAROTID ARTERY

1. In the present study, we examined the effect of a novel angiotensin II type I receptor antagonist, TCV‐116, on carotid neointimal formation after balloon injury in SHR and WKY rats.

α1-Adrenergic Stimulation Induced Hypertrophy in Protein Kinase C Down-Regulated Cultured Cardiac Myocytes

To examine whether protein kinase C (PKC) activation is essential for the induction of cardiac myocyte hypertrophy caused by alpha1-adrenergic stimulation, we investigated the hypertrophic effect of phenylephrine in PKC down-regulated and non-treated cultured cardiac myocytes obtained from neonatal Sprague-Dawley rat ventricles. The treatment with 10 nmol/L 12-tetra decanoylphorbol-13-acetate (TPA) for more than 2 hours decreased PKC activity by approximately 80% without marked hypertrophy. Phenylephrine increased [14C] phenylalanine (Phe) incorporation in both TPA non-treated and treated cells, 1.54- and 1.71-fold as large as control, respectively. The cell surface area also enlarged in both groups, 1.67- and 1.74-fold, respectively. Thus, phenylephrine induced the similar grade hypertrophy in cultured cardiac myocytes even when PKC was down-regulated. These results suggest that conventional PKC activation may not be essential for mediating myocyte hypertrophy by alpha1-adrenergic stimulation.

Analyzing the association between aortic regurgitation and atherosclerosis: is pulse pressure a cause of atherosclerosis?

ABSTRACT If pulse pressure, one of the mechanical stresses, is a risk factor for atherosclerotic cardiovascular disease, then atherosclerosis should be progressive in aortic regurgitation which is a representative disease with increased pulse pressure. This cross-sectional study included 1,149 patients. We examined the influence of aortic regurgitation on maximum intima-media thickness or brachial-ankle pulse wave velocity. The degree of aortic regurgitation was classified into 4 grades by color Doppler examination. There were 177 patients with aortic regurgitation. Pulse pressure was significantly higher in patients with aortic regurgitation than in those without it. On multiple regression analysis, aortic regurgitation was not found to be a significant independent variable for maximum intima-media thickness [standard partial regression coefficient: aortic regurgitation = grade 1, 0.011, P = 0.7635; aortic regurgitation ≥ grade 2, −0.034, P = 0.3289] and brachial-ankle pulse wave velocity [standard partial regression coefficient: aortic regurgitation = grade1, −0.043, P = 0.1197; aortic regurgitation ≥ grade2, 0.002, P = 0.9358] after adjusting for age, sex, body mass index, presence or absence of cardiovascular disease, antihypertensive treatment, diabetes, dyslipidemia, and smoking. These results found no causal association between aortic regurgitation and atherosclerosis, and were a contradiction to the opinion that pulse pressure was a risk factor of atherosclerosis.

Unusual Case of Cardiac Amyloidosis Preceded by a Twenty-year History of Dilated Cardiomyopathy and Heart Failure

Amyloidosis is a well-known but uncommon disease, and the physician must maintain a high index of suspicion in order to make a timely diagnosis. The expected survival of patients with cardiac amyloidosis is generally poor. In particular, survival has been reported to be 4-12 months for patients with amyloid light-chain amyloidosis with congestive heart failure. We herein report a rare case of cardiac amyloidosis in which the patient presented with cardiac hypertrophy after a 20-year history of dilated cardiomyopathy and heart failure.