Pathophysiological significance of sympathetic function in essential hypertension.
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Blood Pressure↗
Biomedical subjects
O Iimura
Publications and source records attributed to O Iimura.
[The role of the Na, K-ATPase inhibitor in renal sodium handling in patients with essential hypertension].
The present study aimed to elucidate the role of Na, K-ATPase inhibitor in renal sodium metabolism in essential hypertension. Mean arterial pressure (MAP), heart rate(HR), urine volume (UV), urinary excretion of sodium (UNaV), endogenous creatinine clearance (Ccr), fractional excretion of sodium (FENa), plasma renin activity(PRA) plasma aldosterone concentration(PAC), plasma noradrenaline concentration (PNA) and urinary excretion of noradrenaline(UNA) were measured before and after intravenous injection of ouabain (0.1 mg/m2.BSA) in 12 normotensive(NT) and 22 mild-to-moderate essential hypertensive subjects(EHT). Following ouabain injection, UV, UNaV FENa significantly increased, but PRA decreased, in both NT and EHT. MAP, HR, Ccr, PNA, and UNA did not change significantly in either group. On the other hand, a significant decrease in PAC was observed in NT, but not in EHT. The changes of UNaV and FENa were significantly attenuated in EHT as compared to NT. No significant difference in change of MAP, HR, UV, Ccr, PNA, UNA, or PRA was demonstrated between NT and EHT. A significantly positive correlation was found between delta UNaV and delta FENa in both NT and EHT, while no significant correlation was observed between delta UNaV and delta MAP, delta UV, delta Ccr, delta PRA, delta PAC, delta PNA and delta UNA in either group. These results suggest that 1) Na, K-ATPase inhibitor clearly augments natriuresis by suppression of sodium reabsorption in renal tubules, 2) since this augmentation was attenuated, there is an elevation of endogenous Na, K-ATPase inhibitor(s) should be considered in EHT, and 3) an increase of the inhibitor might participate to the hypertensive mechanism in EHT.
Adult↗
[The effects of intravenous infused magnesium on hemodynamics and renal water-sodium metabolism in patients with essential hypertension].
Mean arterial pressure (MAP), heart rate (HR), urine volume (UV), urinary excretion of sodium (UNaV), endogenous creatinine clearance (Ccr), fractional excretion of sodium (FENa) were measured before and after intravenous infusion of 10% magnesium sulfate (an initial dose: Mg 13.5 mg/m2.BSA/15 min; a maintenance dose: Mg 2.7 mg/m2.BSA/105 min) in 6 normotensive subjects (NT) and 12 mild-to-moderate essential hypertensives (EHT). Following magnesium infusion, serum magnesium concentration (s-Mg) increased and reached the level of about 1.8 times basal value. Significant increases of UV, UNaV and FENa in both NT and EHT, and a similar tendency of Ccr in EHT were observed, while no significant change in MAP nor HR was found in the two groups. The changes in UNaV (delta UNaV) were positively correlated with those in FENa (delta FENa) and a similar tendency was shown between delta UNaV and change in Ccr (delta Ccr) in all subjects. While there was no significant percentage change of s-Mg (% delta s-Mg) nor of Ccr (% delta Ccr), those of UNaV (% delta UNaV) and FENa (% delta FENa) were significantly greater in EHT. It is concluded from these findings that magnesium infusion produces diuresis and the natriuresis which might result from suppression of renal tubular reabsorption of sodium, without any change in systemic hemodynamics in NT and EHT. The pronounced natriuretic response to magnesium in EHT might contribute to the hypotensive mechanism of magnesium loading in EHT.
Female↗
[The role of catecholamines in hypertensive mechanisms of essential hypertension].
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Adult↗
[A case of intra-ventricular dissociation with dual ventricular tachycardia].
A 63 year old woman with chronic heart failure was admitted to our hospital for palpitation attack on 26th Apr 1988. The patient was died by cardiogenic shock and recurrent ventricular fibrillation 12-hours after admission. The autopsy revealed diffuse myocardial fibrosis and disarray which was compatible with dilated cardiomyopathy. The electrocardiogram on admission showed a peculiar wide QRS tachycardia with atrioventricular dissociation. After intravenous injection of 400 mg of procainamide, the QRS was separated into two types. The one type was left bundle branch block (LBBB) type with right axis deviation (type A), which was similar as that documented on Jan 1985, and the other was LBBB with normal axis (type B). Each wide QRS tachycardias were sustained independently and simultaneously either with RR 440 msec. or with RR 600 msec as if they were dissociated intraventricularly. The different wide QRS tachycardia documented on Feb 1986 was suspected as the fusion beats with type A and the QRS resembling type B. Although ventricular tachycardia with beat-to-beat changes of QRS morphology was generally regarded as bidirectional tachycardia, double foci were considered as origins of the two types of wide QRS tachycardia simultaneously observed in this patient.
Cardiomyopathy, Dilated↗
Effects of nisoldipine on sympathetic activity, the renin-angiotensin-aldosterone system, and water-sodium-calcium metabolism in patients with essential hypertension.
The effects of nisoldipine (Bay k 5552), a long-acting Ca2+ antagonist, on sympathetic activity, the renin-angiotensin-aldosterone (RAA) system, the renal metabolism of water and electrolytes, and parathyroid hormone (PTH) were investigated following single dose and 4 weeks administration. The administration of nisoldipine led to the following results: 1. Mean arterial pressure (MAP) fell and heart rate slightly increased after the first dose, but did not show any appreciable change over 4 weeks treatment. 2. The urinary excretion of sodium, fractional excretion of sodium, plasma renin activity (PRA) and plasma noradrenaline concentration (pNA) were elevated initially, but the trend was to return to pretreatment levels after 4 weeks treatment. 3. A decrease in plasma aldosterone concentration was observed from the commencement of treatment. 4. Urinary excretion of calcium, fractional excretion of calcium and 24-h urine volume (UV) increased from the beginning, and maintained elevated levels after 4 weeks treatment. A decrease in body weight was also observed. 5. Plasma Ca2+ concentration did not change significantly throughout the treatment period, but PTH was decreased significantly both after 1 week and 4 weeks. 6. The percent changes in MAP (% delta MAP) after 4 weeks showed a significant negative correlation with pretreatment levels of MAP and the increment of UV (delta UV), as well as a positive correlation with pretreatment PRA or pNA levels. These findings suggest that in addition to its direct vasodilative effect, suppression of sympathetic activity and the renin-angiotensin-aldosterone system, reduction in body fluid and sodium, and a decrease in PTH and the related calciuresis may contribute to the hypotensive mechanism of nisoldipine.
Adult↗
[Physiological significance of plasma free and conjugated dopamine in healthy volunteers--with special reference to sympathetic nerve activity].
In order to elucidate the physiological significance of plasma dopamine, blood pressure, pulse rate (PR), plasma concentrations of free or conjugated dopamine (free or conjugated pDA), noradrenaline (pNA) and adrenaline (pAd) were measured in 9 healthy volunteers. Blood sampling for the measurements was performed at a basal condition maintaining a supine position for 60 minutes, after twenty minutes 60 degrees head-up tilt (tilt) and an intravenous infusion of 1000 ml 0.9% saline for 2 hours. Following tilt, mean values in diastolic and mean blood pressure, PR, pNA and pAd were significantly increased, while free, conjugated and total pDA were decreased. On the other hand, saline infusion yielded significant decreases in hematocrit, pNA, free, conjugated and total pDA, but blood pressure, PR and pAd remained at the same level. Free/conjugated pDA ratio did not change during tilt or saline infusion. The basal value of free, conjugated or total pDA did not significantly correlate with blood pressure, PR, pNA or pAd, respectively. Furthermore, no significant correlations between the changes in pDAs and hemodynamic parameters, pNA or pAd by tilt or saline infusion were observed. From these results, it was suggested that plasma free or conjugated dopamine in physiological conditions may not be released from sympathetic nerve endings or adrenomedullary glands. Further investigations are needed to clarify the physiological significance of plasma dopamine in humans.
Adult↗
The pathophysiological role of water-sodium balance and renal dopaminergic activity in overweight patients with essential hypertension.
Studies were conducted to evaluate the role of water-sodium balance and renal dopaminergic activity in the hypertensive mechanisms of overweight patients with essential hypertension (EHT). The body mass index (BMI) was correlated positively with mean arterial pressure, plasma volume, extracellular fluid volume, or total exchangeable sodium and negatively with plasma noradrenaline concentration or plasma renin activity in patients with EHT. Fractional excretion of sodium (FENa) was significantly lower in overweight patients than in normal weight patients with EHT. Hypotensive effect of sodium restriction or the natriuretic response to infused dopamine was more remarkable in overweight patients with EHT than in normal weight patients with EHT. Urinary excretion of free dopamine (UDA) was correlated positively with simultaneously measured urinary excretion of sodium or FENa and negatively with the natriuretic response to dopamine infusion. In addition, UDA was positively correlated with the BMI in normal weight patients with EHT, whereas the relation between the UDA and the BMI was significantly negative in overweight patients with EHT. These findings suggest that the expansion of body fluid volume and sodium might result from the blunted natriuretic ability due to an attenuation of the renal dopaminergic activity in overweight patients with EHT. The expansion of body fluid volume and sodium may play an important role in the hypertensive mechanisms of overweight patients with EHT.
Adult↗
The pathophysiological role of digitalis-like substance in essential hypertension.
In order to investigate the role of digitalis-like substance in patients with essential hypertension, levels of plasma digitalis-like substance were measured in nine normotensive, 12 normal-renin and seven low-renin essential hypertensive subjects. The level of plasma digitalis-like substance was determined by using two different methods, the digoxin radio-immunoassay established by our laboratory and Na+,K+-ATPase inhibitory activity (modified Hamlyn's method). There was a significant positive correlation between plasma immunoreactive digitalis-like substance and Na+,K+-ATPase inhibitory activity in plasma samples. Both values were significantly higher in hypertensives than in normotensives. Moreover, Na+,K+-ATPase inhibitory activity was significantly higher in low-renin hypertensives than in normal-renin hypertensives or normotensives. These findings suggest (1) digoxin radio-immunoassay may be able to determine the level of plasma digitalis-like substance; (2) digitalis-like substance is increased in essential hypertensives, especially in low-renin hypertensives; (3) the level of digitalis-like substance might be related to plasma renin activity, and mediated by a change in plasma volume; and (4) the activity of the digitalis-like substance may contribute to the pathophysiology of essential hypertension.
Adult↗
Dobutamine modifies myocardial infarct size through supply-demand balance.
We investigated dobutamine effect on infarct size during permanent coronary artery occlusion in dogs. The coronary artery of closed-chest dog was embolized by a 2.5-mm Teflon bead. Regional flow was measured 8 min after embolization with microspheres and, in drug-treated animals, again 20 min after starting dobutamine infusion (10 micrograms.kg-1.min-1 for 5 h immediately after the first microsphere measurement). The percent of the ischemic region progressing to infarct was determined 48 h later in each animal. Percent necrosis in the control group correlated closely with collateral flow to the epicardial one-third of the ischemic zone normalized against flow to the corresponding layer in the nonischemic zone. This flow should reflect an index of supply (collateral flow) and demand (flow to the nonischemic region determined by autoregulation). Percent necrosis in the drug-treated group did not correlate with normalized collateral flow measurement made before drug infusion, indicating that dobutamine had modified the course of infarction. Percent necrosis correlated well with normalized collateral flow measured during drug infusion, and that relationship was not different from that in the control group. Dobutamine increased infarct size over that expected from the predrug flow measurement in some dogs and reduced it in others. In all cases, however, the drug effect on infarct size was clearly reflected in normalized collateral flow measurement during drug infusion. Percent necrosis correlated with absolute collateral flow but less closely than with the normalized one.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Slow continuous hemodialysis--new therapy for acute renal failure in critically ill patients--Part 1. Theoretical consideration and new technique.
In order to treat acutely uremic patients in an unstable hemodynamic state, we developed a new system for slow continuous hemodialysis. It is well known that continuous hemofiltration or peritoneal dialysis are successful in terms of removing the excess body water without adverse effects on hemodynamics. On the other hand, hemodialysis is far more effective in eliminating solutes such as uremic toxins, especially under a catabolic state. In order to combine the merits of both interventions, volume control and solute removal were dealt with separately in our system. The main system is composed of a double-pump driven closed circuit for the re-circulated hemodialysis. Volume control was achieved accurately within +/- 5% error of the set rate. The dialysance was evaluated in vitro and the efficacy of solute elimination was simulated mathematically. It was speculated that slow continuous hemodialysis could be a new method of treating critically ill patients with acute renal failure.
Acute Kidney Injury↗
Slow continuous hemodialysis--new therapy for acute renal failure in critically ill patients--Part 2. Animal experiments and clinical implication.
Five acutely uremic dogs were treated for 9 hours by means of slow continuous hemodialysis using our newly developed machine. The blood concentrations of urea nitrogen (BUN) and creatinine were determined every hour and were compared to those calculated from a mathematical pool model. In order to assess the accuracy of volume control, the body weight of dogs was monitored continuously by scale bed, under simultaneous 200 ml/hour infusion and ultrafiltration. Arterial and swan-ganz catheter were inserted to measure hemodynamic changes during hemodialysis. The efficacy of solute elimination was coincidental with the predicted value. The error of volume control was within +/- 5% of set rate. Hemodynamic parameters were not significantly influenced in spite of a large amount of volume exchange. In conclusion, it was demonstrated that slow continuous hemodialysis could be a better alternative to peritoneal dialysis, continuous hemofiltration or conventional hemodialysis in order to treat acute renal failure in critically ill patients, in terms of solute removal, volume control and the effects on hemodynamics.
Acute Kidney Injury↗
The dual effects of hemodialysis on cardiac function assessed by pulsed Doppler echocardiography.
To assess the effect of hemodialysis on cardiac function, a change of preload due to water removal was considered. In order to keep the preload constant during hemodialysis, extracorporeal ultrafiltration was induced before hemodialysis (step 1), and then hemodialysis without water removal was achieved (step 2). Cardiac performance in 8 patients was evaluated before and at the end of each step using pulsed doppler echocardiography. Step 1: Ultrafiltration was 1350 +/- 410 ml and hematocrit increased significantly. Left ventricular end-diastolic dimension (LVDd) decreased from 40.3 +/- 4.2 (mean +/- standard deviation) mm to 36.1 +/- 4.6 mm (p less than 0.005) and aortic peak flow velocity (PFV) also decreased from 59.9 +/- 16.0 cm/s to 49.0 +/- 11.0 cm/s (p less than 0.005). Step 2: In contrast, after hemodialysis without water removal, the mean velocity of circumferential fiber shortening (mVcf) increased from 1.36 +/- 0.26 circ/s to 1.86 +/- 0.36 circ/s (p less than 0.005). PFV and average acceleration (Aa) increased from 49.0 +/- 11.0 cm/s to 63.8 +/- 11.4 cm/s (p +/- 0.001) and from 750 +/- 220 cm/s/s to 1270 +/- 280 cm/s/s (p less than 0.001), respectively. During this step, serum potassium and osmolality decreased significantly. In conclusion, hemodialysis improves cardiac function under constant preload condition and this is due to the direct effects of hemodialysis by the correction of electrolytes and osmolar components such as uremic toxin.
Adult↗
Benign ventricular tachycardia in systemic sarcoidosis--a case of false tendon.
A 22-year-old female patient was diagnosed as having systemic sarcoidosis with pulmonary, skin and ocular lesions, and ventricular tachycardia in resting ECG. Although cardiac sarcoidosis was strongly suspected at diagnosis, no clinical symptom such as palpitation or syncope developed during the three year observation period. Cardiac silhouette was unchanged in chest X-ray and 201thallium myocardial scintigraphy revealed no abnormality. Ventricular complex was suppressed by exercise or tachycardia. Two-dimensional echocardiogram showed abnormal fascicular bands attached from the mid-septum to the apex (false tendon). Therefore, it was concluded that this benign form of ventricular tachycardia might be due to the false tendon, rather than to the cardiac involvement of sarcoidosis. The cause of arrhythmia is important when evaluating the prognosis of a patient with a systemic disease.
Adult↗
Morphological assessment of left ventricular wall and ventricular aneurysm by thallium-201 myocardial emission computed tomography.
To evaluate the influence of left ventricular (LV) aneurysm on non-infarcted ventricular wall, the shape of the left ventricular wall was assessed by thallium-201 single photon emission computed tomography (SPECT). From the morphology of the ventricular wall close to the apex, the rest images along the transaxis, horizontal long axis and vertical long axis were classified into 4 types: convergent, parallel, divergent and completely defective. LV aneurysm was detected by 2-dimensional echocardiography and/or contrast left ventriculography in 39 of 80 patients with previous myocardial infarction. Although convergence in the normal configuration of ventricular walls close to the apex, 4 of 39 patients with LV aneurysm showed this pattern. The divergent type was very specific (100%) and the most sensitive (56.4%) of the 4 for identifying LV aneurysm. Moreover, the parallel configuration indicated aneurysm in cases of inferoposterior infarction and all the completely defective cases exhibited this abnormality. Thus, thallium-201 SPECT is suitable for observing the morphology of the ventricular wall and can provide highly reliable information for detecting postinfarction ventricular aneurysm with a sensitivity of 89.7%, a specificity of 87.8% and a diagnostic accuracy of 88.8%.
Adult↗
The interference of acebutolol administration in the measurement of urinary 17-ketosteroid by Zimmermann's method.
A patient with essential hypertension receiving the oral administration of acebutolol, a beta 1-selective adrenergic blocker, showed a marked increase in urinary 17-ketosteroid (17-KS) excretion determined by Zimmermann's method. Since the normal concentration of each fraction of 17-KS was found in this case by gas chromatography, the possibility of an abnormality in steroid metabolism could be excluded from the mechanism of the increase in the measured value for urinary 17-KS. In the urine samples from patients treated with acebutolol, acebutolol and acetylated acebutolol, a main metabolite of acebutolol, were found equally among them. Moreover, acebutolol or acetylated acebutolol resulted in a dose-dependent increase in 17-KS by Zimmermann's method in phosphate buffered saline or in a urine sample. However, the other beta-blockers, such as propranolol, alprenolol and oxprenolol did not show any effect on the determined value for urinary 17-KS. Thus it was concluded that the activated methylene group of acebutolol and acetylated acebutolol may interfere with the measured values obtained by Zimmermann's method.
17-Ketosteroids↗
Inspiratory right ventricular outflow obstruction in a patient with hypertrophic cardiomyopathy.
A patient with familial hypertrophic cardiomyopathy with exertional near syncope is reported. Intra-right ventricular obstruction was demonstrated by hemodynamic studies during inspiration and the Valsalva maneuver with systemic hypotension. Improvement occurred following the administration of propranolol. It was suggested that syncope might be precipitated by hemodynamic changes such as a high output state and a depressed cardiac volume in relation to intra-right ventricular obstruction in patients with hypertrophic cardiomyopathy.
Adolescent↗
Comparative double-blind study of ketanserin versus propranolol in the treatment of essential hypertension.
To clarify the antihypertensive effect, safety and clinical usefulness of ketanserin, a comparative double-blind study was carried out in 277 patients with essential hypertension using propranolol as a control drug. Ketanserin 10 to 30 mg twice daily and propranolol 20 to 40 mg 3 times daily were administered for 12 weeks. The results showed no difference in antihypertensive effect and clinical usefulness between the drugs. In the ketanserine group, plasma concentration of total cholesterol was decreased significantly, and the reduction in heart rate was less than in the propranolol group. These findings suggest that ketanserin may satisfactorily control blood pressure.
Adult↗