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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Maladaption to hemodynamic overload, especially to arterial hypertension, has important clinical implications, and it is necessary to obtain criteria in order to discriminate physiological and pathological growth processes. We investigated the physiological growth of intramyocardial arteries in the rat heart. A new stereological method was introduced to determine the length of intramyocardial arteries from counts on histological sections. Four groups of male Sprague-Dawley rats of different ages were investigated. The growth rate of arteries was characterized by the growth coefficient b according to the exponential function y = axb (allometric growth function). Analysis of left ventricular weights (LVW) and total lengths of left ventricular intramyocardial arteries (L) revealed Lv = constant.LVW0.71 (r = 0.77, P < 0.001). The growth coefficient b < 1 indicates that the arterial supply of the heart, i.e. the length density of arteries Lv (length per unit myocardial volume), decreases during normal growth. Empirically, we found L = constant.LVW-0.28 (r = 0.43, P < 0.01). Previously, we estimated growth rates of b = 0.33 for the total length of left ventricular myocytes and b = 0.71 for the total length of capillaries. Thus, growth of intramyocardial arteries considerably exceeds the length increase of myocytes, but is proportional to the length increase of capillaries. Growth analysis of total mitochondrial volume using historical data of our group revealed proportionality to arteries, as well (b = 0.76). This indicates that growth of arteries and capillaries may be determined by oxygen consumption.
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PMID:Physiological growth of arteries in the rat heart parallels the growth of capillaries, but not of myocytes. 129 16

Renal erythropoietin production is dependent on local oxygen content of blood which activates so called "oxygen sensors". Taking into consideration altered local renal blood supply in patients with arterial hypertension in the course of arteritis (HA) and from the other side contribution of the renin-angiotensin system in both pathogenesis of hypertension and regulation of erythropoietin production it seemed plausible to undertake this study. The aim of the study was to determine whether and in what extent patients with HA and healthy subjects differ in EPO secretion and whether EPO serum level is related in this patients to renin response to dietary sodium restriction and upright position of the body. 18 patients with HA and 12 healthy subjects were investigated. In all subjects haematocrit value, haemoglobin concentration, erythrocyte count, sodium, potassium, creatinine, iron, ferritin serum levels, total iron binding capacity, plasma renin activity (PRA), erythropoietin serum level and mean arterial blood pressure (MAP) were measured in basic conditions (normal sodium diet). Additionally PRA, EPO and MAP were measured after dietary sodium restriction to 10-20 mmol Na/24 hrs for three days and upright position of the body for three hours. Patients with HA had insignificantly lower serum EPO concentrations than healthy subjects and both studied groups did not differ in haematocrit value and determinants of iron metabolism except of significantly higher ferritin concentration in HA. After dietary sodium restriction and upright position of the body significant rise in PRA and no significant changes in EPO level were found in studied groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[The role of erythropoietin in blood pressure regulation in patients with arteritis]. 130 May 62

30 subjects of old and middle age (28 male, 2 female) with obstructive sleep apnea syndrome (OSAS) and 20 normal subjects with matchable age and body weight (14 male, 6 female) as control were studied with nocturnal polysomnography for at least 7 hours. Right arm blood pressure was determined in supine position before and after sleep. Meantime, three 8-hour urine specimens, two collected while awake and one during sleep were examined for urinary levels of epinephrine (E) and norepinephrine (NE) with fluorometric method. All OSAS subjects (mean apnea index 42.9) had significant arterial oxygen desaturation (mean 63.9%). 12/30 OSAS subjects had definit history of essential hypertension. They described that hypertension appeared months or years after the onset of sleep disorders. Before sleep the blood pressure in OSAS subjects was higher than that in controls (mean 133/90 mmHg versus 118/77 mmHg P < 0.001). After 7 hours of sleep with apnea events, the blood pressure rose to 149/100 mmHg (P < 0.001). whereas in the controls there was no change of statistic significance (mean 115/77 mmHg). A diurnal rhythm in free catecholamines excretion was apparent for both NE and E (P < 0.05) in the controls, while in OSAS there was no normal diurnal rhythm. 24-hour values of NE were remarkably higher than those in controls. It is known that up to 40% of OSAS subjects is in the population of essential hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Obstructive sleep apnea syndrome and essential hypertension: diurnal variation of urinary catecholamines]. 130 54

Changes in a plasma endogenous digitalislike substance were investigated in relation to the antihypertensive mechanism of mild exercise. Fifteen women with mild essential hypertension and seven normotensive female volunteers were divided into exercised hypertensive (n = 10), nonexercised hypertensive (n = 5), and nonexercised normotensive (n = 7) groups. A 4-week general clinical observation period preceded the study period of 10 weeks. The exercised hypertensive individuals were treated with a lactate threshold exercise that corresponded to approximately 50% of the maximum oxygen consumption three times a week, whereas the nonexercised groups were observed at the outpatient clinic as control groups. In the exercised group, systolic blood pressure fell by 7 mm Hg (p = 0.05), diastolic by 6 mm Hg (p less than 0.01), and mean blood pressure by 7 mm Hg (p less than 0.01) after 10 weeks. The reduction in the plasma endogenous digitalislike substance was significant after 7 (-1.02 ng/ml, p less than 0.05) and 10 (-1.04 ng/ml, p less than 0.05) weeks in this group. It positively correlated with the reduction in diastolic (r = 0.70, p less than 0.05) or mean (r = 0.66, p less than 0.05) blood pressure and with changes in plasma norepinephrine (r = 0.76, p less than 0.05). The mean corpuscular volume of erythrocytes decreased (-1.7 fl, p less than 0.01) after 10 weeks of exercise, and the plasma volume index tended to decrease (-108 ml/m2, p = 0.28). In the control groups, significant changes in blood pressure and plasma endogenous digitalislike substance were not observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1992 Feb
PMID:Mild exercise decreases plasma endogenous digitalislike substance in hypertensive individuals. 131 Apr 82

The effects of isradipine on ambulatory blood pressure, platelet aggregation, and oxygen free radicals were assessed in 30 patients with hypertension in a non-comparative 16-week study. After 4 weeks of placebo run-in, patients received isradipine at 2.5 mg twice daily for 12 weeks. The average supine systolic/diastolic blood pressure (155 +/- 17/101 +/- 11 mm Hg) was significantly reduced at the end of treatment (144 +/- 13/95 +/- 9 mm Hg; p less than 0.01). The heart rate was not significantly altered. Isradipine had no adverse effects on red or white blood cells or on plasma viscosity. The thromboxane B2 level and epinephrine-induced platelet aggregation were significantly (p less than 0.05) reduced. High-density lipoprotein cholesterol was significantly (p less than 0.01) increased after vs. before treatment; total cholesterol was significantly (p less than 0.05) increased at midstudy, but this was not significant at the end of the study. Other biochemical parameters were unchanged. Studies of neutrophil oxygen free radicals by serum opsonized zymosan and phorbol myristate acetate were not affected by isradipine. In conclusion, isradipine is an effective antihypertensive agent that also has beneficial effects on platelet aggregation and lipids while having no effects on neutrophil oxygen free radicals or most of the biochemical variables tested, making it an ideal agent for hypertension.
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PMID:Effects of the calcium antagonist isradipine on 24-hour ambulatory blood pressure, platelet aggregation, and neutrophil oxygen free radicals in hypertension. 137 32

This study compared the effects of clinically prescribed doses of cilazapril, nifedipine, and atenolol on maximal exercise performance in physically active subjects. In a double-blind crossover trial, 10 healthy male volunteers performed progressive aerobic exercise to exhaustion for determination of maximal oxygen consumption (VO2 max), after single dose ingestion of cilazapril, nifedipine, atenolol, and placebo. Measurements were made at exhaustion and at a single submaximal workload (250 W). Exercise time to exhaustion and peak workload were decreased by all agents (p less than 0.05 vs. placebo), but VO2 max was decreased by atenolol only (p less than 0.05 vs. placebo). Although both atenolol and cilazapril decreased the maximum systolic blood pressure, the peak heart rate was decreased only by atenolol (p less than 0.001 vs. placebo). Whereas submaximal oxygen consumption, minute ventilation, and blood lactate concentrations were not different between groups, ratings of perceived exertion were increased during submaximal exercise by atenolol and cilazapril (p less than 0.05 vs. placebo). Cilazapril, nifedipine, and atenolol all impaired exercise performance and increased ratings of perceived exertion during submaximal exercise without altering rates of oxygen consumption or blood lactate accumulation. Maximal exercise performance was impaired to a greater extent by atenolol than by nifedipine or cilazapril. This study suggests that either angiotensin-converting enzyme inhibitors or calcium-channel antagonists might be preferable for the management of hypertension in athletic patients as they have a lesser effect on exercise performance, at least in healthy individuals.
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PMID:The effects of antihypertensive medications on the physiological response to maximal exercise testing. 138 88

The determinants of cardiac output were investigated in 161 patients with essential hypertension World Health Organization (WHO) stages I and II. In multiple regression analysis, cardiac output was inversely and independently related to blood pressure and to age. In patients with more severe hypertension, the lower cardiac output was associated with a lower stroke volume and a higher peripheral oxygen extraction. When age and blood pressure were taken into account, cardiac output was not a significant predictor of total mortality and of future cardiovascular events. Clinic and casual blood pressure explain only up to about 30% of the variability of echocardiographic left ventricular mass. The relationship of electrocardiographic voltages with blood pressure at various levels of bicycle exercise was highly significant in 169 patients with essential hypertension (r = 0.29-0.38; p less than 0.001) but the relationship was not better than with pressure at rest (r = 0.39). Ambulatory blood pressure, however, may be better related to left ventricular mass than clinic pressure. Several studies indicate that left ventricular hypertrophy is a significant risk factor for future cardiovascular events, independent of age and blood pressure. Left ventricular systolic function is usually normal in established hypertension, but diastolic function is frequently impaired, which could explain the reduced peak oxygen uptake in patients with more severe hypertension.
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PMID:Hypertensive heart disease: pathophysiology and clinical and prognostic consequences. 138 96

The present investigation was undertaken to observe the effects of head point-cardiovascular point needling on the cardiac function and hemodynamics in 8 anesthetized dogs, and to elucidate the underlying mechanisms and its clinical implications. Cardiovascular point needling might induce significant changes in cardiac function and hemodynamic parameters: arterial systolic pressure decreased by 22.4 +/- 8.88 from 104.6 +/- 20.55 mmHg, diastolic pressure by 16.7 +/- 8.04 from 66.5 +/- 18.03 mmHg, mean arterial pressure by 18.6 +/- 8.16 from 79.2 +/- 18.36 mmHg, left ventricular end-diastolic pressure by 0.3 +/- 0.47 from 3.6 +/- 1.94 mmHg, Lv dp/dt max by 300.1 +/- 200.1 from 2000.1 +/- 700.8 mmHg/s, coronary resistance by 399 +/- 310 from 1959 +/- 1150 dyn.s.cm-5, femoral arterial resistance by 242 +/- 634 from 2438 +/- 1595 dyn.s.cm-5, total peripheral resistance by 1570.7 +/- 691.0 from 9000.2 +/- 2537.4 dyn.s.cm-5, and left ventricular work index by 2.7 +/- 1.9 from 11.4 +/- 5.17 kg.m/min/m2, whereas the coronary sinus blood flow increased by 0.7 +/- 1.6 from 33.6 +/- 14.7 ml/min. There were significant differences between the values of all parameters before and after cardiovascular point needling (p greater than 0.005). The results indicated that cardiovascular point needling was capable of lowering the cardiac preload and afterload with resultant fall in blood pressure and cardiac oxygen consumption, as well as relaxing the coronary vessels and consequent increase in coronary blood flow with enhanced oxygen supply. These beneficial effects induced by cardiovascular point needling provided the basis for the treatment of hypertension, coronary artery diseases and cardiac failure in clinic.
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PMID:[Effects of head point needling on cardiac function and hemodynamics]. 139 51

The purpose of the present study was to assess possible racial differences in cardiovascular and plasma catecholamine responses to dynamic exercise. A biracial group of normotensive college-age men (15 blacks, 15 whites) were tested for maximal oxygen uptake, resting blood pressure, and heart rate. Subjects then rode a cycle ergometer at 25%, 50%, and 75% of peak oxygen uptake (6 minutes at each stage). Blood pressure and heart rate were measured during supine rest, seated rest, and at each stage of exercise with an automated blood pressure monitor. At each stage, venous blood was sampled to allow determination of plasma norepinephrine and epinephrine, and cardiac output was measured with the carbon dioxide rebreathing technique. The results indicated that resting blood pressure was similar for blacks and whites (114/68 versus 115/68 mm Hg, respectively). Blacks exhibited greater systolic and diastolic blood pressures during submaximal dynamic exercise. However, blacks also showed a trend toward a positive parental history of hypertension, which has been associated with an increased pressor response. Racial differences did not exist for heart rate or cardiac output, but blacks had higher values for total peripheral resistance both at rest and during exercise. Although no overall racial differences were seen for plasma catecholamine concentrations at rest, blacks had significantly lower levels of norepinephrine (1,275 versus 1,556 pg/ml) and higher levels of epinephrine (306 versus 216 pg/ml) than whites at the highest work rate. The current study confirms the increased pressor response to exercise in normotensive blacks. Blacks had an elevation in total peripheral resistance that was not accompanied by an increase in plasma norepinephrine levels.
Hypertension 1992 Oct
PMID:Cardiovascular and plasma catecholamine responses to exercise in blacks and whites. 139 89

Physical endurance training as practised at spas in the active treatment of hypertension will usually result in an increase in oxygen supply reserves and will also improve haemodynamics, so that it could help in objectively identifying the success of cardiovascular treatment. For this reason we conducted a bicycle ergometer load test in recumbent position in a group of 23 male hypertensives in stages I and II (age between 25 and 58 years) before and after a treatment course at a spa of 4 to 5 weeks' duration. The measurement parameters were ECG, blood pressure, cardiac output and the ventilatory parameters tidal volume, oxygen uptake, respiratory equivalent and respiratory quotient. Significant blood pressure reductions were seen if the load did not exceed 75 watts. The treatment course had a definite influence on cardiac output at rest and under stress. The treatment course achieves reduction and largely also normalisation of the tidal volume which is otherwise higher than in healthy persons. No influence is exercised on the respiratory equivalent. Reduction of the tidal volume and of the oxygen uptake, as well as reduction of the respiratory quotient after the treatment course can be interpreted as an improvement in the economy of the cardiovascular system. The ventilatory parameters are only conditionally suitable for arriving at an objective assessment of the curative effect of the treatment course.
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PMID:[Ventilation and hemodynamics as control parameters of spa treatment]. 141 27


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