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Biomedical subjects

K Fukiyama

Publications and source records attributed to K Fukiyama.

At least 127 records · Page 7Linked to original sources
PubMed1988

Effect of chronic inhibition of angiotensin converting enzyme on baroreceptor reflex in essential hypertension.

We examined baroreflex function and plasma angiotensin II (Ang II) before and after the treatment with an angiotensin converting enzyme inhibitor (ACEI) in eight inpatients with essential hypertension (EHT). Baroreflex sensitivity (BS), expressed as a slope of linear relationship between %-changes in mean blood pressure (BP) and those in plasma concentration of norepinephrine (pNE), was greater during BP reduction by sodium nitroprusside (SNP) than during BP elevation by phenylephrine (PE). Enalapril treatment for 7 days reduced BP without a significant change in heart rate and pNE. It also increased the BS in two cases during SNP infusion and in four cases during PE infusion. Ang II was not significantly reduced after enalapril, while plasma ACE activity was suppressed by about 80% and plasma renin activity (PRA) was elevated. The changes in BS did not correlate with the changes in Ang II. The shift of barofunction curve with an enhancement of BS by enalapril therapy might not be attributed solely to the interaction between circulating Ang II and central baroreflex mechanisms.

Angiotensin II↗
PubMed1987

Efficacy and safety of ramipril (HOE 498) in the treatment of hypertension: dose finding study.

An open-label, prospective multicenter trial of ramipril was performed. The agent was administered once daily at an initial dosage of 1.25 mg and this was increased, when necessary, up to 10 mg with intervals of 2 weeks for 8 weeks. Effectiveness in 46 patients with mild to moderate essential hypertension was 28.1% at a dosage of 1.25 mg, 52.2% at 2.5 mg, 69.6% at 5 mg and 78.3% at 10 mg of ramipril alone. In 27 patients receiving baseline therapy with a thiazide diuretic, a subsequent administration of ramipril showed effectiveness in 11.1% for 1.25 mg, 48.1% for 2.5 mg and 70.4% for 5 mg. Adverse effects occurred in 11.7% of patients overall and were not serious. One patient was withdrawn because of severe headache; the other patients tolerated the treatment well. A dosage of 2.5 to 10 mg of ramipril will probably be appropriate for further evaluation of the effectiveness of this agent in a double-blind study.

Adult↗
PubMed1986

Blood pressure and sympathetic nervous function in spontaneously hypertensive rats derived from breeders on low sodium diet.

We investigated the effect of dietary salt restriction in spontaneously hypertensive rat (SHR) breeders to determine if the development of hypertension of offspring would be blunted. Weaning SHRs (F-0) were divided into 3 groups and were given a diets containing sodium of 0.4% (G 1), 0.05% (G 2), or 0.4% plus mefruside 0.001% (G 3) with distilled water. Potassium content was 0.75% and the other ingredients except chloride were identical in all the diets. Offsprings (F-1) were derived from selective inbreeding within each group. Systolic blood pressure rose over 160 mmHg by 8 weeks of age in all the male rats of all the groups in both F-0 and F-1. There was no difference in blood pressure between G 1 and G 2 at any age, while in G 3 blood pressure was significantly lower than in G 1 at 12 and 20 weeks of age in F-1. The findings in pressure were ascertained by heart-body weight ratio determined at autopsy, which was similar between G 1 and G 2, and was smaller in G 3 than the others at 20 weeks of age. Aldostrone excretion rate was markedly higher in G 2 than G 1 and G 3 at all study points, whereas plasma renin content was similar between G 1 and G 2, and higher in G 3. Plasma concentrations of noradrenaline and adrenaline did not differ among the 3 groups at any age in both F-0 and F-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Cardiovascular reactivity in adult rats pretreated at a suckling age with intracerebroventricular 6-hydroxydopamine.

To investigate functional differences in noradrenergic mechanisms of cardiovascular regulation between the hypothalamus and the brainstem, cardiovascular responses to various stimuli were examined in mature rats pretreated with 6-hydroxydopamine (6-OHDA) given i.c.v. at a suckling age which is known to provoke low norepinephrine concentrations in the hypothalamus but not in the brainstem or in peripheral organs. Under alpha-chloralose anesthesia the resting mean arterial pressure (MAP) was significantly lower in the 6-OHDA treated group than in the control group. Pressor response and associated reflexbradycardia produced by i.v. injection of phenylephrine in the two groups were similar. Likewise, carotid occlusion response and clonidine-induced hypotension and bradycardia did not differ between the two groups. Electrical stimulation of the sciatic nerve elicited increases in MAP and heart rate in both groups. However, pressor responses in the treated rats were significantly less than in the controls. Increases in heart rate during stimulation in the treated group were larger than in the controls. These results indicate that a long-lasting depletion of norepinephrine in the rat hypothalamus leads to a deterioration of basal level of blood pressure and somatosympathetic reflexes, yet baroreflexes remain intact.

Animals↗
PubMed1985

Neurogenic hypertension in the Guillain-Barré syndrome.

We report a case of Guillain-Barré syndrome associated with hypertension. The hypertension was related to glossopharyngeal and vagal nerve impairment. Plasma noradrenaline concentration (NA) and plasma renin activity (PRA) were elevated. The possible mechanism of the neurogenic hypertension produced by the sino-aortic denervation is discussed.

Adolescent↗
PubMed1984

The renin-angiotensin-aldosterone system and circadian rhythm of urine variables in normotensive and hypertensive subjects.

Forty-two middle-age male subjects, aged from 47 to 54 years old, were divided into three groups; 14 normotensives (NT), 16 borderline hypertensives (BHT) and 12 hypertensives (HT). The environmental effects were neutralized as much as possible by keeping their activities synchronized and their plasma and urine variables simultaneously investigated using the same protocol as under normal physiologic conditions. The circadian rhythms of urinary excretions of Na, K, Cl, creatinine, aldosterone, adrenaline and noradrenaline were analyzed by a multivariate method (cosinor method). Both systolic and diastolic blood pressure were statistically significantly different among the three groups and body weight was greater in HT than in NT. Other plasma and urine variables examined, however, were not significantly different among the three groups. A statistically significant circadian rhythm was detected in the urine variables. The rhythm characteristics, such as the mesor, amplitude and acrophase, of the urine variables except for the acrophase of urinary Na excretion were not significantly different among the three groups; the circadian acrophase of urinary Na in HT and BHT appeared significantly earlier than in NT. The pathophysiological and clinical significance of the earlier appearance of the circadian acrophase of urinary Na in hypertensive subjects still remains a unique characteristic requiring further investigation.

Aldosterone↗
PubMed1984

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.

Adolescent↗
PubMed1983

Recurrent pheochromocytoma associated with glucagonoma. A case report.

We treated a hypertensive patient with recurrent pheochromocytoma (paraganglioma) associated with glucagonoma. No clinical symptom of glucagonoma was found and it could be detected only by a slight elevation of plasma immunoreactive glucagon (IRG) while the extirpated pancreatic tumor contained much IRG. This case could not be classified as either multiple endocrine neoplasia (MEN) type I or type II.

Adenoma, Islet Cell↗
PubMed1982

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.

Adult↗
PubMed1982

Augmented sympathetic nervous function in young subjects with borderline hypertension.

In order to elucidate the mechanism of blood pressure elevation in the patients with borderline hypertension, the sympathetic nervous activity was investigated and the following results were obtained: 1) Plasma catecholamine (CA) levels were elevated in young men but not in middle-aged men with borderline hypertension in comparison with age-matched normal men. 2) Cardiovascular responsiveness to exogenous CA was not augmented in young men with borderline hypertension. 3) Cerebrospinal fluid noradrenaline levels were elevated in young men with borderline hypertension. They correlated positively with plasma NA or blood pressure. 4) In young men with borderline hypertension, plasma and urinary CAs were not altered by hypertonic saline loading. These results suggest that increased activity of the central and peripheral sympathetic nervous system is an important mechanism of blood pressure elevation in young subjects with borderline hypertension.

Adult↗
PubMed1982

Renin response to furosemide differs with the routes of administration in health men.

Plasma renin activity (PRA) was serially determined 0, 15, 30, 60 and 120 min following administration of furosemide in a dose of 40 mg intravenously (i.v.) and 80 mg orally (p.o.) at a one week interval in 10 healthy men. Following i.v. furosemide administration, PRA increased rapidly and reached a plateau level of 6.1 +/- 1.0 ng/ml/h (222 +/- 44% of the control), at 15 min and remained at about the same level throughout the remaining period of the study. In contrast, PRA increased progressively to a maximum level of 5.5 +/- 0.7 ng/ml/h (285 +/- 53% of the control), 120 min after p.o. furosemide. In case of p.o. furosemide, the increase in PRA was dependent on the doses used per body weight, and was significantly correlated with the cumulative sodium excretion by itself, or the cumulative sodium excretion adjusted by either the leanness index or the body surface area. Such relationships were not apparent after i.v. furosemide. These findings suggest that the response of renin release to furosemide in healthy men differs with the routes of administration and renin release with p.o. furosemide may be largely due to a net sodium loss, while mechanism(s) other than sodium loss may be involved in the early hypersecretion of renin with i.v. administration of furosemide.

Administration, Oral↗
PubMed1982

Evaluation of plasma renin activity by blood pressure level (pressure-renin index) in patients with essential hypertension.

Under various conditions of sodium balance, 1-sarcosine-8-isoleucine angiotensin II was infused into 15 normotensive controls and 82 patients with benign essential hypertension. Changes in mean blood pressure induced by the analogue were correlated with the logarithm of plasma renin activity (r = -0.763, p less than 0.001 for the controls; r = -0.776, p less than 0.001 for the patients). Although the coefficients of determination were much the same, 0.95 confidence limits of the regression line did not overlap at renin levels over 7 ng/ml/h. At those levels, a decrease in the mean blood pressure induced by the analogue was greater in the hypertensive patients. A pressure-renin index was defined as a product of the logarithm of plasma renin activity and the mean blood pressure measured before the analogue infusion. The correlation between the analogue effect and the pressure-renin index was highly significant (r = -0.763, p less than 0.001 for the controls; r = -0.777, p less than 0.001 for the hypertensive patients). The regression line (0.95 confidence limit) for the hypertensives coincided with that for the normotensives. Thus, the blood pressure level should be taken into account when attempting to evaluate plasma renin activity.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1982

Comparison of the immediate hemodynamic effects of SQ 14225 (Captopril) and [Sar1, Ileu8] angiotensin II in patients with dialysis resistant hypertension.

The effects of a single dose of 50 mg of SQ 14225 (Captopril) and 0.6 microgram/kg/min infusion of angiotensin II antagonist, [Sar1, Ileu8] (AII-A), were examined in six patients with dialysis resistant hypertension and seven with normal blood pressures. A depressor effect of Captopril was observed even in patients with AII-A unresponsive dialysis resistant hypertension. The fall in mean arterial pressure (MAP) was significantly correlated with the fall in the total peripheral resistance index (TPRI) following both Captopril administration (r = 0.883, P less than 0.01) and AII-A infusion (r = 0.735, P less than 0.01). Basal plasma renin activity (PRA) was the same in patients with dialysis resistant hypertension as in normotensive patients and correlated with the fall in MAP induced by AII-A infusion (r = -0.640, P less than 0.05). It was concluded that the direct effect of the renin-angiotensin system was uncertain in patients with dialysis resistant hypertension and that the depressor effect of Captopril was not secondary to the suppression of angiotensin II formation.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1981

Renin dependent hypertension by dissecting aortic aneurysm. A case report.

A 49-year-old female patient with dissecting aortic aneurysm and severe hypertension was reported. Aortogram revealed dissection of De Bakey type IIIb, which extended to the iliac artery and caused occlusion of the left renal artery. Peripheral plasma renin activity was extremely elevated and 1-Sar-8-Ile-angiotensin II produced a marked fall in blood pressure. The patient was treated conservatively with antihypertensive agents for about 4 years from July, 1974 to October, 1978 when she died suddenly in an early morning.

Aortic Dissection↗