Yuhei Kawano

Elevated plasma catecholamines without alteration in cardiovascular responsiveness in young men with borderline hypertension

Plasma catecholamines and cardiovascular responses to upright posture, exogenous noradrenaline (NA), and isoproterenol (IP) were examined in 20 young men with borderline hypertension and in 10 age-matched normotensive volunteers. Resting plasma NA and adrenaline (Ad) levels were higher in the borderline hypertensive patients. Significant correlations were found among plasma NA and mean blood pressure (MBP) or heart rate (HR), and between plasma Ad and HR in all individuals in the supine position. The increases in plasma NA were similar between groups for orthostatic positions. Pressor response to exogenous NA and chronotropic response to exogenous IP were not augmented in borderline hypertensives. A negative correlation was found between plasma NA before infusion and the increases of MBP produced by NA or the increases of HR produced by IP in all the individuals. Our observations suggest that there is hyperactivity of the sympathoadrenal system without enhancement in cardiovascular reactivity to catecholamines in young men with borderline hypertension.

Acute and chronic effects of a hypocaloric diet on 24-hour blood pressure, heart rate and heart-rate variability in mildly-to-moderately obese patients with essential hypertension.

We examined the acute and chronic effects of a nutritionally balanced, moderately hypocaloric diet on 24-hour ambulatory blood pressure, heart rate and heart-rate variability in mildly-to-moderately obese patients with essential hypertension. We enrolled 16 obese patients with essential hypertension [age: 51-76 years, body mass index (BMI): 26-32 kg/m2]. For the initial week, a standard diet of 2,000 kcal/day was given, followed by a 3-week of a hypocaloric diet of 850 kcal/day. In the last period of the standard diet and in the first and the last periods of the hypocaloric diet, each subjects 24-hour ambulatory blood pressure, heart rate and R-R intervals of the electrocardiogram were recorded, and electrolytes and catecholamines in 24-hour urine samples were also measured. A power spectral analysis of the heart-rate variability was performed over a 24-hour period based on the autoregressive method. The subjects lost 3.7+/-0.3 kg (mean +/- s.e.m.) of body weight during the 3-week hypocaloric diet period. The 24-hour blood pressure did not differ between the last period of the standard diet and the first period of the hypocaloric diet; however, it showed a significant reduction after 3 weeks of the hypocaloric diet. The decrease in the 24-hour blood pressure during the study period was 10.5+/-1.5 mm Hg systole and 4.3+/-1.8 mm Hg diastole. In contrast, the 24-hour heart rate was significantly reduced in the first period of the hypocaloric diet, although the body weight and blood pressure did not change, and the rate was maintained even in the last period of the hypocaloric diet. The decrease in the 24-hour heart rate during the study period was 2.8+/-0.9 beats per minute. The hypocaloric diet did not change any autonomic indices obtained from a power spectral analysis of the heart-rate variability. In conclusion, different responses to a hypocaloric diet were observed between the blood pressure and the heart rate in obese hypertensive patients. The changes in power spectral parameters of the heart-rate variability were less apparent than those found with the blood pressure or the heart rate.

Catecholamines, Angiotensin II and Sodium Concentrations in Cerebrospinal Fluid in Young Men with Borderline Hypertension

To evaluate the role of central nervous mechanisms and their relationships to the peripheral sympathetic nervous system in borderline hypertension, we measured catecholamines, angiotensin II (AII) and sodium (Na) concentrations in cerebrospinal fluid (CSF) with plasma catecholamines concomitantly in 12 young men with borderline hypertension and 7 age-matched healthy normotensive men on ordinary salt intake. Plasma norepinephrine (NE) and epinephrine (E) were higher in the borderline hypertensives than in the normotensives (NE: 239 +/- 15 vs 190 +/- 11 pg/ml, p less than 0.05, E: 83 +/- 9 vs 43 +/- 6 pg/ml, p less than 0.01). NE levels in CSF were also higher in the borderline hypertensives than in the normotensives (200 +/- 15 vs 150 +/- 18 pg/ml, p less than 0.05). In most of the subjects, CSF E and plasma and CSF dopamine levels were below the sensitivity of the assay. CSF NE correlated positively with both plasma NE (p less than 0.01) and mean blood pressure (p less than 0.05) in all subjects. Immunoreactive AII and Na concentrations in CSF did not differ between the borderline hypertensives and normotensives. These results suggest that peripheral sympathoadrenal overactivity in young subjects with borderline hypertension may be related to an altered function of central noradrenergic neurons. AII and Na in the central nervous system do not appear to have an important role in borderline hypertension.

Atrial Natriuretic Peptide, Angiotensin, Norepinephrine and Electrolyte in Cerebrospinal Fluid of Essential Hypertension

We determined concentrations of atrial natriuretic peptide (ANP), angiotensin (Ang), norepinephrine (NE) and electrolyte in plasma and cerebrospinal fluid (CSF) to study possible roles of these substances within the brain in human hypertension. Blood and CSF samples were obtained from 10 patients with mild to moderate essential hypertension (EHT) aged 40-65 y and 10 age-matched normotensive subjects (NT) on a regular salt diet (8 g/day). Levels of ANP, NE, Na, K, Ca and Cl in CSF and plasma were comparable between EHT and NT. Plasma renin activity, plasma and CSF Ang II were lower in EHT than NT. CSF Ang III tended to be lower in EHT. There was no correlation between CSF and plasma ANP, or between CSF and plasma Ang II. Our results indicate that CSF levels of ANP may not be altered in middle aged patients with mild to moderate hypertension. It is also suggested that Ang II, NE and sodium in the central nervous system may not have important roles in hypertension of those patients.

Efficacy of percutaneous transluminal coronary angioplasty in chronic hemodialysis patients: our second report.

薬物治療に抵抗する狭心症を合併した維持血液透析中の12例 (男8, 女4例, 平均年齢は56.3歳) に対する経皮的冠動脈形成術 (PTCA) の治療成績について検討した. 合計27狭窄病変に対してPTCAを施行し, 22狭窄病変 (82%) の拡張に成功した. 不成功例は2例で, そのうちの1例は小脳出血により死亡したが, 他の11例では重篤な合併症は出現しなかった. 患者成功は12例中10例 (83%) で, 非透析例と同等の治療成績であった. 11例の平均追跡期間は2年5か月で, 狭心症が4例に再発し, 3例には再度PTCAを施行し, 全例成功した. 透析患者に対する冠動脈バイパス術はいまだにhigh riskとされていることから, 透析患者の難治性狭心症に対しては, 解剖学的に禁忌・不適応でない限り, PTCAが第一選択と考えられた.

Two cases with reversible ST-segment depression on electrocardiogram during hemodialysis and normal coronary arteries.

血液透析中に心電図上のST下降が認められたにもかかわらず, 冠動脈造影で有意狭窄病変 (70%狭窄以上) がなかった2症例を経験した. 症例1は28歳の女性で, 慢性腎炎による慢性腎不全で透析導入1年後に透析中の胸痛を主訴として入院した. 透析開始2時間後に胸痛が出現し, 心電図でST下降を示した. ニトログリセリンの舌下服用で胸痛が増悪した. 除水を中止し, 生理食塩水100mlを静注したところ, 胸痛が消失し, 心電図も正常化した. 冠動脈造影では有意狭窄が認められなかった. 症例2は49歳の男性で, 糖尿病性腎症のため血液透析を導入した. 透析開始2時間後に無症候性に心電図上ST下降が出現した. 透析中のST下降時に心筋シンチグラフィーを施行したところ, 左室前壁側に心筋虚血所見が検出されたため冠動脈造影を行った. しかし, 有意狭窄は認められなかった.症例1ではST下降時に胸痛を伴ったこと, 症例2ではST下降時の心筋シンチグラフィーで心筋虚血所見が認められたことから, これら2例の心電図ST下降は心筋虚血に起因すると考えられた. 冠動脈造影所見が正常であっても透析患者では貧血や左室肥大, また基礎疾患として高血圧, 糖尿病, 高脂血症, 腎不全に基づく心筋障害が存在するために透析中の血圧低下によって心筋虚血が生じることを示唆した.