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Biomedical subjects

J Staessen

Publications and source records attributed to J Staessen.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Sympathetic modification of the relationship between salt intake and blood pressure in the general population].

Using pulse rate and urinary sodium as indices of sympathetic tone and salt intake, respectively, we investigated whether both an increased sympathetic activity and a high salt consumption are needed to increase blood pressure in the population at large. A random population sample of 2081 subjects with a minimum age of 18 years was stratified by tertiles of pulse rate. In subjects with a slow and in those with a fast pulse rate, a significant curvilinear relation between blood pressure and urinary sodium was found, while in the middle pulse rate third the correlation was not significant. A significant interaction between pulse rate and urinary sodium indicated that, when urinary sodium increased from 160 to 300 mmol/24 h, both systolic and diastolic pressure rose in subjects with a fast pulse rate, but declined in those with a slow pulse rate. In conclusion, our results suggest that a high salt intake is associated with an elevated blood pressure in subjects with a high sympathetic tone, but with a decreased pressure in individuals with a low sympathetic activity.

Blood Pressure↗
PubMed1989

Possible biochemical mechanisms involved in the antihypertensive drug-induced changes in serum lipoproteins.

The antihypertensive drug-induced changes in serum lipoproteins can be attributed to two major mechanisms, namely an increased hepatic lipoprotein synthesis and a disturbed lipoprotein catabolism. Thiazides, by inhibiting phosphodiesterase, increase the intracellular concentration of cyclic AMP leading to a stimulation of lipolysis. beta-Blockers may reduce the adenylate cyclase activity in liver cells, leading to a reduced inhibition of the liver triglyceride synthesis and a higher secretion of VLDL triglyceride particles. alpha-Blockade through phosphodiesterase inhibition and an increased cAMP level, can result in a blockade of the liver triglyceride synthesis and a reduced serum triglyceride concentration. Lipoprotein lipase activity is reduced by beta-blockers and stimulated by alpha-blockers, leading, respectively, to a lower and a higher plasma HDL cholesterol. Besides these two major mechanisms, a direct effect of antihypertensive drugs on intracellular cholesterol synthesis can also be postulated.

Animals↗
PubMed1988

The pulmonary circulation in essential systemic hypertension.

Seventy-one men, ages 16 to 59 years, were referred for systemic hypertension, which was without detectable cause and with limited organ damage (World Health Organization stages I to II). They performed a graded exercise test on the bicycle ergometer in the sitting position. Mean brachial intraarterial pressure, mean pulmonary artery and wedge pressures and cardiac output (Fick method) were measured. At rest mean brachial artery pressure ranged from 72 to 168 mm Hg. Mean pulmonary wedge pressure was significantly (p less than 0.05) related to mean brachial artery pressure at rest, at submaximal work (50 watts) and at the end of exercise (161 +/- 42 [standard deviation] watts). In each subject pulmonary vascular resistance was calculated as the slope of the relation between the pressure gradient across the pulmonary circulation and cardiac output from data at rest, at 50 watts and at the end of exercise; mean critical closing pressure was calculated as the intercept of this relation. Pulmonary vascular resistance averaged 0.63 +/- 0.37 mm Hg/liter/min and was significantly related to age (r = 0.28, p less than 0.05) but not to rest brachial artery pressure (r = 0.14) or pulmonary wedge pressure (r = 0.09, difference not significant for both). The mean critical closing pressure averaged 6.1 +/- 4.0 mm Hg and was not related to brachial artery pressure (r = -0.08) or to age (r = -0.18, difference not significant for both). It is concluded that there is neither a primary nor a secondary effect of systemic hypertension on the pulmonary vasculature in patients with World Health Organization stages I to II essential hypertension.

Adolescent↗
PubMed1988

Effects of opioid antagonism on the haemodynamic and hormonal responses to exercise.

1. Physical effort involves, along with an increase in the plasma concentration of beta-endorphin, profound adaptations of the circulation and the endocrine system. The effects of opioid antagonism on the responses of blood pressure, heart rate and several hormones to exercise were therefore studied in 10 normal men. They exercised in the supine position up to 33% and 66% of their maximal exercise capacity and received in a randomized double-blind cross-over protocol, either saline or naloxone (10 mg intravenously, followed by a continuous infusion of 10 mg/h). 2. Intra-arterial pressure and heart rate were continuously monitored, but were not affected by naloxone. 3. At rest, opioid antagonism produced a rise in plasma renin activity and in plasma adrenocorticotropin, cortisol and aldosterone, but only the stimulation of the two adrenocortical hormones differed significantly from the control experiments; at rest naloxone also prevented the fall in plasma adrenaline, which occurred with saline infusion. Furthermore, the exercise-induced rises in plasma angiotensin II, aldosterone, cortisol, noradrenaline and adrenaline were higher on naloxone than on saline, while a similar tendency was also present for the increases with exercise in plasma renin activity and plasma adrenocorticotropin. Neither at rest nor during exercise did opioid antagonism alter plasma lactate and glucose and serum insulin and growth hormone. 4. In conclusion, (1) endogenous opioids are not involved in the responses of blood pressure and heart rate to supine exercise; (2) at rest and during exercise, the endogenous opioids inhibit the secretion of adrenocorticotropin, aldosterone, cortisol, noradrenaline and adrenaline; (3) they also inhibit the plasma renin-angiotensin II system indirectly via the catecholamines.

Adrenal Cortex Hormones↗
PubMed1988

Blood pressure during long-term converting-enzyme inhibition predicts the curability of renovascular hypertension by angioplasty.

Percutaneous transluminal renal angioplasty (PTRA) was performed in 28 hypertensive patients with 50% or more unilateral renal artery stenosis. Prospectively, the study compared the extent to which systolic (SBP) and diastolic (DBP) pressure during long-term converting-enzyme inhibition (CEI) and the ipsi- to contralateral renal vein renin ratio (RVR) predicted success of PTRA, defined as SBP less than 160 mmHg and DBP less than 95 mmHg. Both SBP and DBP after PTRA were positively correlated with pressure during CEI (P less than 0.001) and negatively with RVR (P less than 0.03). In multiple regression these associations were independent and remained statistically significant. In discriminant analysis, a SBP during CEI less than 160 mmHg, a DBP during CEI less than 95 mmHg, and a RVR greater than or equal to 1.5 identified with equal accuracy the success of PTRA. Furthermore, in patients with a SBP during CEI less than 160 mmHg, the demonstration of a RVR greater than or equal to 1.5 increased (P less than 0.05) the prediction of a positive outcome from 50 to 67%. In contrast, in 92% of the patients with a SBP during CEI greater than 160 mmHg, PTRA was not successful. Thus, blood pressure measurements during long-term CEI predict the curability by PTRA of renovascular hypertension and can be employed either alone or in association with the RVR.

Angioplasty, Balloon↗
PubMed1988

Mortality in various intervention trials in elderly hypertensive patients: a review.

Results on total and cause-specific mortality from various randomized intervention trials on antihypertensive drug treatment in elderly hypertensives are reviewed, compared and pooled. Mortality from all causes tended to decrease in all trials, but this decrease was not statistically significant in any of the trials separately, nor when all results were pooled. When the results of all the trials were combined, there was a significant overall decrease in cardiovascular mortality of 28%. This decrease in cardiovascular mortality was mainly related to a significant reduction in cerebrovascular mortality of 41%. Mortality from coronary heart disease also tended to decrease by 28%, but statistical significance was not reached.

Aged↗
PubMed1988

Erythrocyte and leucocyte sodium and potassium transport systems during long-term diuretic administration in men.

The effect of xipamide on the intracellular concentration and transmembrane fluxes of Na+ and K+ was studied in 12 normal male subjects, using a double-blind cross-over design. After a run-in period on placebo for 1 week, the subjects were treated with either placebo (n = 6) or xipamide 20 mg once a day (n = 6) for 16 weeks and were then switched to the alternative medication for another 16 weeks. The intra-erythrocyte and intra-leucocyte Na+ concentration was increased by 11 and 7%, respectively, during xipamide administration, while the intracellular K+ concentration was decreased by 3 and 4%, respectively. No significant effect of xipamide could however be demonstrated on the ouabain-sensitive, bumetanide-sensitive or ouabain-bumetanide-resistant 86Rb uptake and on the maximal 3H-ouabain binding in erythrocytes and leucocytes. The red cell Na+-Li+ countertransport was also not changed in the xipamide-treated subjects. Our data suggest that the increased intracellular Na+ concentration and the decreased K+ concentration in red and white blood cells of xipamide-treated subjects cannot be attributed to changes in the activity of the Na+ pump, the Na+-K+ cotransport or Na+-Li+ countertransport system or to changes in the number of active Na+ pump units.

Adult↗
PubMed1988

Maximal aerobic power in essential hypertension.

Fifty untreated male patients aged 32 +/- 10 (s.d.) years, referred for hypertension, in whom organ damage was limited to WHO stages I and II, without underlying disease, performed a graded, uninterrupted exercise on a bicycle ergometer up to exhaustion. Mean brachial intra-arterial pressure at rest ranged from 74 to 152 mmHg. Maximal voluntary oxygen uptake was independently and negatively related to resting blood pressure (P less than 0.05), age (P = 0.05), and positively to body weight (P less than 0.05). Pulmonary wedge pressure and the components of the Fick equation--heart rate, stroke volume and arteriovenous oxygen difference--were measured in order to study the mechanisms involved. Stroke volume at peak exercise was inversely (P less than 0.05), and pulmonary wedge pressure positively (P less than 0.01), related to mean brachial artery pressure at rest. Peak heart rate was not significantly related to the severity of hypertension, but was inversely related to age (P less than 0.01). Stroke volume and pulmonary wedge pressure at the end of exercise were both similar in older and younger patients. Arteriovenous oxygen difference at peak exercise was not related either to blood pressure or to age. In conclusion, both high blood pressure and age reduce maximal voluntary oxygen uptake independently of each other by separate mechanisms; the former by an impairment of cardiac function, the latter by the limitation of peak heart rate.

Adult↗
PubMed1988

Salt intake and blood pressure in the general population: a controlled intervention trial in two towns.

A controlled trial was conducted in two Belgian towns to investigate the feasibility and effects of a reduction in salt consumption at the community level. The low-sodium intervention in one town was mainly directed at women and implemented through mass media techniques, while the control town was merely observed. Cross-sectional random sampling at baseline and 5 years later was employed, the participation rate being similar (67%) in the two towns. During the study a total of 2211 subjects were examined. In adult women (greater than or equal to 20 years) in the intervention town the 24-h urinary excretion of sodium (UVNa) decreased by 25 mmol/24 h (P less than 0.001) and this reduction differed (P = 0.01) from the concurrent trend in UVNa in the control town (+8 mmol/24 h). However, both systolic (SBP, -7.5 versus -7.9 mmHg) and diastolic (DBP, -2.3 versus -3.0 mmHg) pressures declined to a similar extent in the women from the two towns. In adult men in the intervention town, decreases were observed in UVNa (-12 mmol/24 h) and in SBP (-5.6 mmHg) and DBP (-2.4 mmHg), but these trends were not significantly different from the concurrent changes in the control town (-14 mmol/24 h, -4.9 and +0.2 mmHg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Short-term double-blind comparison of doxazosin and atenolol in patients with mild to moderate hypertension.

The antihypertensive effect and safety of doxazosin once-daily was compared with that of atenolol once-daily in 40 patients with mild to moderate hypertension. During the first 4 weeks all patients received placebo therapy. During the subsequent 10 weeks patients were randomized to doxazosin or atenolol treatment. Treatment was initiated with 1 mg doxazosin or 50 mg atenolol once-daily. The dose could be doubled biweekly until a final dose of 16 mg doxazosin or 100 mg atenolol was reached. The average final dose of doxazosin was 6.4 +/- 0.8 mg (SEM) and that of atenolol 66.7 +/- 5.7 mg. During the 10 weeks of active treatment, the systolic and diastolic blood pressure tended to be lower (p less than 0.05) in patients on atenolol, this difference was however not significant for the standing blood pressure. Recumbent and standing heart rate were lower (p less than 0.01) during atenolol. Multiple regression analysis showed that in the doxazosin group the recumbent systolic blood pressure after 10 weeks of treatment was significantly (p less than 0.05) and independently related to age, recumbent systolic blood pressure at randomization, and the changes in recumbent heart rate. In neither group severe adverse reactions were observed. However, two patients on doxazosin dropped out of the study: one because of blurred vision and persistent high blood pressure, and one because of fatigue and palpitations. No patient dropped out of the atenolol group during the study.

Adult↗
PubMed1988

Double-blind comparison of ketanserin and propranolol in hypertensive patients.

In this double-blind study in general practice, 444 patients were randomized to ketanserin (K, 40 mg b.i.d.) and 229 patients were randomized to propranolol (P, 80 mg b.i.d.). After 3 months, more patients on K (15%) than on P (9%) had been withdrawn (p less than 0.02). Although at 3 months the falls in systolic blood pressure (SBP) and diastolic blood pressure (DBP) were similar in both groups, the reduction in SBP was slower on K, and up to 2 months SBP was higher on K than on P (p less than 0.04 or less). At randomization and after 3 months, average weights were similar in both groups. However, during the first month of the study, patients on K gained weight, and this change in weight differed (p less than 0.02) from the unchanged weight on P. On K, BP lowering was greater when weight gain was less. Multiple regression analysis showed that after adjusting for BP at randomization and subsequent weight changes, DBP at 1 month on K was lower with advancing age, whereas SBP and DBP at 1 and 3 months on P were higher with age. Severe adverse effects were absent. However, dry mouth, edema, fatigue, and dizziness occurred more frequently with K (p less than 0.04 or less).

Adolescent↗
PubMed1988

The relationship between blood pressure and environmental exposure to lead and cadmium in Belgium.

The question whether in the general population environmental exposure to lead and cadmium influences blood pressure after controlling for confounding factors remains debated. The environmental exposure of the Belgian population to both lead and cadmium is high as compared with other countries. The Cadmibel Cooperative Study was therefore designed to elucidate whether environmental exposure to lead and cadmium has any effect on blood pressure and renal function in the population at large. Before embarking on the large Cadmibel project, a small study was conducted. Blood pressure and the 24-hr urinary excretion of cadmium (CdU) and lead (PbU) were determined in a random 4% sample of the population of a small Belgian town. CdU averaged 0.27 micrograms/24 hr in 46 youths (mean age 14 +/- 3 years, +/- SD), increased with age, and was higher in 57 adult men (age 41 +/- 14 years), as compared with 59 adult women (age 39 +/- 14 years) (1.05 vs. 0.81 micrograms/24 hr; p less than 0.01). PbU averaged 5.8 micrograms/24 hr in youths and similarly increased with age; adult men excreted more lead than women (13.3 vs. 8.3 micrograms/24 hr; p less than 0.001). Among men, manual workers excreted more cadmium (1.4 vs. 0.8 micrograms/24 hr; p less than 0.05) but a similar amount of lead (7.0 vs. 6.9 micrograms/24 hr) as compared with office workers. In simple regression analysis, CdU was positively correlated with both systolic (r = 0.30; p less than 0.05) and diastolic (r = 0.38; p less than 0.01) blood pressure in women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Antihypertensive drug treatment in elderly hypertensive subjects: evidence of protection.

The different intervention trials in elderly hypertensive subjects are compatible with the hypothesis that antihypertensive drug treatment decreases cardiovascular mortality, mainly by a reduction of cerebrovascular mortality. Antihypertensive drug treatment in elderly hypertensive subjects also leads to a decrease in fatal and nonfatal cardiovascular and cerebrovascular events. It has not yet been proven whether antihypertensive drug treatment should be recommended for symptomless patients with isolated systolic hypertension and for patients with uncomplicated hypertension above the age of 80 years.

Aged↗
PubMed1988

The relationship between body weight and blood pressure.

In adults of Western societies the positive relationship between blood pressure and body weight has often been demonstrated, both cross-sectionally and longitudinally. This correlation is even stronger in children and early adulthood. In most studies in children, the association between age and blood pressure disappears after controlling for weight. Association must be differentiated from causation. It has however been shown in several intervention studies that treatment of obesity by weight loss decreases blood pressure substantially both in hypertensive and normotensive subjects. Although combining results from several intervention trials is difficult this is the only practical way to get an overall estimate of the hypotensive response to be expected from weight reduction. In the randomised controlled intervention studies, conducted in obese hypertensive patients and reviewed in the present meta-analysis, a decrease in body weight by 1 kg resulted in a reduction of systolic and diastolic pressure by 1.2 and 1.0 mmHg, respectively. Blood pressure generally decreased before normal weight was achieved and remained reduced as long as there was no marked regain in body weight. Although a decrease in salt intake during dieting may contribute to the blood pressure lowering effect of weight reduction, also other mechanisms, such as a reduction in plasma renin activity and a decrease in sympathetic tone may also be involved.

Adrenal Cortex Hormones↗
PubMed1988

In vitro effect of xipamide on sodium-potassium transport systems in human erythrocytes.

The in vitro effects of xipamide in a concentration range of 10(-8) to 10(-2) M were investigated on various Na+ and K+ transport systems in human red blood cells. Xipamide inhibited the anion carrier or DIDS-sensitive LiCO3- -influx starting from a concentration of 10(-5) M. However, a decrease in the Na+, K+-pump and the Na+, K+-cotransport activity and a rise in the passive permeability of the cell membrane was only observed starting from a concentration of 10(-4) M xipamide.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗