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Biomedical subjects

H Muratani

Publications and source records attributed to H Muratani.

At least 73 records · Page 4Linked to original sources
PubMed1989

Effect of single-administration captopril on plasma and urinary vasopressin in normotensive subjects and patients with essential hypertension and primary aldosteronism.

Effects of a single administration of captopril on plasma and urinary vasopressin (AVP) were examined in 8 normotensive (NT) female volunteers, 17 patients with essential hypertension (EHT) and 2 patients with primary aldosteronism (PA). Orally-administered captopril (25 mg) had no effect on plasma AVP levels in the three groups. However, urinary excretion of AVP decreased significantly after use of captopril in both NT and EHT subjects (-57% and -67%, respectively), and also in PA subjects. The magnitude of reduction in urinary AVP was significantly correlated with the pretreatment levels of plasma renin activity (r = 0.85) and plasma aldosterone concentration (r = 0.88) in NT subjects. Such correlation was not found in EHT subjects. These results suggest that captopril decreases AVP secretion in both normotensive and hypertensive subjects, but the relation of the magnitude in AVP reduction by captopril to the peripheral renin-angiotensin system might be different.

Adult↗
PubMed1989

Effects of sodium depletion and orthostasis on plasma and urinary vasopressin in normal subjects.

We investigated the effects of sodium depletion and orthostasis on the plasma concentration and urinary excretion of vasopressin (AVP) in eight normal female subjects. After 4 days on a sodium controlled diet (130 mEq/day), the subjects were placed on a low sodium diet (30 mEq/day) for 3 days and 120 mg of furosemide was administered orally on the first day of the low sodium regimen. Sodium depletion in the present study reduced body weight by 1.6 kg and increased hematocrit by 3.5%. A significant (p less than 0.05) increase in plasma AVP and a significant (p less than 0.05) decrease in 24-h urinary excretion of AVP were observed during sodium depletion. One-hour ambulation significantly increased plasma AVP in both control and sodium depleted phases (p less than 0.01). The percent change in plasma AVP tended to correlate with that in mean blood pressure in the control phase (r = 0.69, 0.05 less than p less than 0.1), and significantly correlated in the sodium depleted phase (r = 0.86, p less than 0.01). The present results suggest that AVP may play an important role in the maintenance of blood pressure during orthostasis in the sodium depleted state.

Adult↗
PubMed1989

Sympathetic response to oral glucose load is altered in hypertensive subjects.

Blood pressure, plasma norepinephrine (NE) and epinephrine (E) levels in responses to oral glucose load (OGTT) and to head-up tilting (Tilt) were measured in 14 hypertensive (HT) and 17 normotensive subjects (NT). In response to OGTT, NE significantly increased within 30 minutes (+25 +/- 8%; p less than 0.05) in NT, followed by a decline to the basal level, while it remained unchanged in HT (+5 +/- 8%). E decreased similarly during OGTT in both groups. Mean blood pressure, however, fell only in HT (-3.3 +/- 1.1%; p less than 0.05) but did not change in NT. Blood pressure, NE and E responses to Tilt did not differ between NT and HT. These results suggest that hypertensive subjects have some defects in sympathetic activation in response to glucose loading.

Administration, Oral↗
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↗
PubMed1988

Long-term prognosis of malignant hypertension; difference between underlying diseases such as essential hypertension and chronic glomerulonephritis.

A long-term prognosis was studied in 69 patients with malignant hypertension, followed for an average of 56 months. Overall survival rate was 90% for a 5-year period, although the prognosis was different between two major underlying diseases, namely the 5-year survival was 79% for 33 essential hypertension (EHT) and 100% for 26 chronic glomerulonephritis (CGN); the difference is significant (p less than 0.01). In contrast, the 5-year rate for renal survival, defined as the probability of surviving without hemodialysis, was 37% in all cases. However, there was significant difference in the renal survival between EHT (60% for a 5-year period) and CGN (4% for a 18-month period). Multivariate analyses of the Cox's proportional hazards model revealed that the long-term change in renal function was different between the two groups, namely more rapid deterioration in the CGN group. These results indicate that a long-term prognosis of malignant hypertension is influenced by the underlying diseases and hemodialysis besides antihypertensive treatment may increase survival in malignant hypertension associated with severely damaged renal function.

Adult↗
PubMed1987

Pathophysiology in malignant hypertension: with special reference to the renin-angiotensin system.

Pathophysiology of malignant hypertension, of which underlying disease was essential hypertension (EHT) in 33 cases and chronic glomerulonephritis (CGN) in 26 cases, was studied with reference to the renin-angiotensin system. Plasma renin activity (PRA) was significantly higher in the EHT than in the CGN group, and angiotensin II antagonist [Sar1, Ile8]angiotensin II (AIIA) induced a significant lowering of blood pressure only in the former group. PRA was linearly correlated with both pretreatment mean blood pressure (MBP, r = 0.474, n = 29, p less than 0.01) and serum creatinine (r = 0.540, n = 29, p less than 0.01) in the EHT group but not in CGN patients, although there was an inverse correlation between PRA and serum sodium in both groups. Multiple regression analysis revealed that PRA was independently related to MBP, serum creatinine, and serum sodium in the EHT group, but not in the CGN group. These results suggest that the renin-angiotensin system plays a significant role in elevating blood pressure and deteriorating renal function in malignant hypertension derived from EHT, but it is less important in CGN related hypertension.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1987

Single oral administration of captopril may not bring an improvement in screening of primary aldosteronism.

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in 19 cases with primary aldosteronism (PA) and 72 with essential hypertension (EHT) to differentiate the two disorders in the following conditions: after overnight recumbency (basal state) and after oral administration of captopril. Screening criteria were determined in order to pick up all of PA patients as positive. After the captopril administration, the specificity of a criterion based on the combination of PAC and PAC/PRA ratio was 93% and positive predictive value 79%. This criterion was superior to other conventional screening methods. However, higher specificity (97%) and positive predictive value (90%) were obtained from a combination criterion based on the basal PAC and PAC/PRA ratio. The single oral administration of captopril may not bring an improvement in the screening of PA.

Aldosterone↗
PubMed1986

Is single oral administration of captopril beneficial in screening for primary aldosteronism?

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in 19 cases with primary aldosteronism (PA) and in 72 with essential hypertension (EHT) to differentiate the two disorders during the following conditions on normal salt diet: after overnight recumbency (basal state) and 2 hours after oral administration of 25 mg of captopril. Screening criteria were determined so that all PA patients were diagnosed as positive, and their specificities were compared with those of other conventional screening methods for PA. After captopril administration, the specificity of a criterion based on a combination of PAC and PAC/PRA ratio was 93% and positive predictive value was 79%. This criterion was superior to blood pressure response to angiotension II analog infusion, PRA on salt depletion, and to PAC on salt loading. However, higher specificity (97%) and positive predictive value (90%) were obtained from a criterion based on a combination of basal PAC and PAC/PRA ratio. Therefore, the use of a combination criterion based on PAC and PAC/PRA ratio at basal state rather than after captopril administration may give a satisfactory result in the screening for PA.

Adult↗
PubMed1985

[Plasma aldosterone concentration in patients with primary aldosteronism in the last decade].

We analyzed the chronological variation of plasma aldosterone concentration (PAC) in 27 surgically confirmed patients with primary aldosteronism (PA) during the period from 1975 to 1984. PAC values in PA-patients were significantly higher than those in 82 age-matched patients with essential hypertension (EHT). However, although average PAC in the PA-patients declined consistently in recent years, no chronological trend of PAC was observed in the EHT-patients. Therefore, the distributions of PAC in the two groups of patients overlapped in the last few years. Such chronological variations of PAC in the PA-patients were not related to serum potassium concentration, blood pressure level on admission, duration of hypertension, or diameter of the adrenal adenomas. In some recently observed cases of PA, not only was the basal PAC relatively low, PAC also responded to either salt depletion or salt loading. These findings could not be explained simply by the change of methodology for PAC determination but rather by the technological advance of diagnostic radiology. As a result, PA might be diagnosed in the early stages or before becoming fullblown. Further study should be necessary to clarify the exact mechanism.

Adult↗
PubMed1985

Circadian rhythms of urinary excretions of water and electrolytes in patients receiving total parenteral nutrition (TPN).

In order to determine whether the usual feeding pattern actually modifies the circadian rhythms of urinary excretion of water and electrolytes, we compared the circadian rhythm characteristics in patients receiving total parenteral nutrition (TPN group) with those in patients on an ordinary hospital diet (control group). Statistically significant circadian rhythms were detected in all of the urinary variables investigated herein by using the population mean-cosinor method in both groups. In addition, there were no statistically significant differences of the mesor, the %-amplitude and the acrophase between the two groups. These results suggest that the usual feeding pattern is not a main determinant in forming the circadian rhythm characteristics of human urinary variables.

17-Hydroxycorticosteroids↗
PubMed1984

[A simple radioimmunoassay determination of urinary aldosterone using 125I-labeled ligand [ALDOCTK-125KIT] and its clinical application].

A method of radioimmunoassay for urinary aldosterone excretion (AER) using 125I-labeled ligand [ALDOCTK-125KIT] is described. The sensitivity, specificity, reproducibility and accuracy of this method were compared with the 3H-RIA method previously reported. Since the extraction method using ALDOCTK-125KIT was considered to be preferable to the direct method, the former method was applied to the present study. An excellent correlation was found between the values determined by the 3H-RIA method and the extraction method (r = 0.935, p less than 0.001, Y = 0.89X + 0.80, n = 146). The within-assay and the between-assay coefficient of variation was 7.7--15.0% and 9.7--12.2%, respectively. As a clinical application, the circadian variation of AER was investigated in 5 control subjects and groups of essential hypertension (EHT), primary aldosteronism (PA), chronic glomerulonephritis (CGN) and Cushing's syndrome, each of which consisted of 5 patients, all of which had serum creatinine concentrations of less than 1.2 mg/dl. Under a control diet containing 10 g of salt per day, urine was collected in 4-hour pools starting at 8:00 for the ensuing 24 hours, and AER was determined by means of both 3H-RIA and the extraction method. The difference of the values between the peak and the nadir in each subject was statistically significant, and marked and identical circadian variations of AER with the peak and the nadir at the period of 4:00 to 12:00 and 20:00 to 4:00 were observed in the control, EHT, PA and CGN groups. In the Cushing group, however, the circadian variation of AER was different from the other 4 groups: the peak and the nadir of AER occurred at the period of 20:00 to 24:00 and 4:00 to 8:00, respectively. The circadian variation of AER became more obvious in all groups including the Cushing, when each value was expressed in the percentage of the mean. AER under the control diet was 9.38 +/- 2.04 micrograms/day in the control subjects. In PA and CGN, AER was significantly higher, and in the Cushing group, it was significantly lower than that observed in the control. However, no difference was found in AER between the control and EHT. AERs in both 4-hour and 24-hour urine specimens measured by ALDOCTK-125KIT were consistent with those by the 3H-RIA method.

Adolescent↗
PubMed1984

A possible role of hypokalemia in the manifestation of high QRS voltage and sinus bradycardia in patients with primary aldosteronism.

We analyzed electrocardiograms obtained from 29 Japanese patients with primary aldosteronism (PA) and in 106 patients with essential hypertension (EHT). QRS voltage was higher (p less than 0.05) and heart rate was slower (p less than 0.01) in cases of PA. A significant reduction in QRS voltage and a significant increase in heart rate were observed after short-term potassium replacement or after short-term administration of spironolactone, preoperatively, and within 2 to 4 weeks after the removal of aldosteronoma. These significant changes in QRS voltage and heart rate were always accompanied by significant increases in the serum potassium concentration but not always by a reduction in blood pressure. The long-term follow-up of EHT-patients showed a slower reduction in their high QRS voltage, despite effective antihypertensive therapy. Thus, hypokalemia, in addition to hypertension, may be relevant to the high QRS voltage in PA. There also appeared to be a relationship between hypokalemia and bradycardia.

Adult↗
PubMed1983

Activation of renin-angiotensin system in maintenance of high blood pressure in uncomplicated pheochromocytoma--a case report.

In a patient with an uncomplicated pheochromocytoma, we observed high basal value of plasma renin activity (PRA), 16.2 ng/ml/h, and a remarkable elevation in PRA from 18.2 to 90.4 ng/ml/h and concomitant blood pressure reduction following a single oral administration of 25 mg of captopril. The response was same as that observed in renovascular hypertensives, and disappeared during the period of alpha-, beta-blocker administration or after the surgery. Basal PRA also returned to low normal level. The renin-angiotensin (R-A) system probably had a role in the maintenance of high blood pressure. The mechanism of the activation of the R-A system was thought to be renal vasoconstriction due to excessive circulating catecholamines.

Adrenal Gland Neoplasms↗