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Biomedical subjects

J Staessen

Publications and source records attributed to J Staessen.

At least 181 records · Page 10Linked to original sources
PubMed1986

Blood pressure and urinary cations in urban Bantu of Zaire.

The 24-hour urinary excretion of sodium, potassium, calcium, and magnesium and their relationship to arterial blood pressure were investigated from December 1983 to May 1984 in a 10% random sample (n = 666) of urban Bantu of Kinshasa, Zaïre. In youths aged 10-19 years, blood pressure averaged 109/60 mmHg, and the 24-hour urinary excretion of sodium, potassium, calcium, and magnesium averaged 84 mmol, 30 mmol, 483 mumol, and 2 mmol, respectively. After adjustment for age and body weight, a weak positive association became apparent between diastolic pressure and the urinary sodium to potassium ratio in girls and all youths. In adults aged greater than or equal to 20 years, blood pressure averaged 124/72 mmHg, and the 24-hour urinary excretion of sodium, potassium, calcium, and magnesium averaged 87 mmol, 33 mmol, 828 mumol, and 1.88 mmol, respectively. After adjustment for sex, age, body weight, and pulse rate in all adults, systolic pressure was significantly and positively correlated with urinary sodium excretion and negatively correlated with urinary potassium excretion, while diastolic pressure was weakly associated with urinary calcium excretion. In women, an independent and significant association was also observed between systolic pressure and 24-hour urinary sodium. When instead of the 24-hour urinary excretion of sodium and potassium, the sodium to potassium ratio was considered as an independent variable in multiple regression analysis, both systolic and diastolic pressure were independently and positively related to the sodium to potassium ratio in all adults. These results indicate that in this urban Bantu population, age and body weight are the major predictors of systolic pressure in youths and the major predictors of both systolic and diastolic pressure in adults. The sodium to potassium ratio did contribute to the prediction of blood pressure in girls and when, in youths as well as in adults, both sexes were considered together. Urinary calcium was associated with diastolic pressure only in all adults.

Adolescent↗
PubMed1986

Epidemiological study of blood pressure and hypertension in a sample of urban Bantu of Zaïre.

Blood pressure and anthropometric characteristics were studied in a 10% random sample (n = 675) of Bantu, aged greater than or equal to 10 years and living in an urban quarter of Kinshasa, Zaïre. The prevalence and awareness of hypertension as well as the therapeutic situation in adult participants aged greater than or equal to 20 years were also evaluated. Systolic and diastolic blood pressure tended to be higher in males than in females. In adults greater than or equal to 20 years, systolic and diastolic pressure were positively and independently correlated with both age and body weight. In youths (10-19 years old), systolic pressure was associated with age and body weight, while in girls diastolic pressure was related to age only. Using WHO criteria, the overall prevalence of definite hypertension in adults was 9.9% (13.6% in males and 6.8% in females). The prevalence of borderline hypertension was 7% (8.4% in males and 5.6% in females). Of the participants studied with definite and borderline hypertension (n = 49), 69% were not aware of their blood pressure elevation; 31% were aware, but only 13% were treated and 3% were controlled. It is concluded that hypertension is not uncommon in these urban Bantu and that programmes for screening and educating the population should be developed and implemented.

Adolescent↗
PubMed1986

Relationships between blood pressure and urinary sodium, potassium, calcium and magnesium in Bantu of Zaire.

The relationships between blood pressure and 24-h urinary sodium, potassium, calcium and magnesium were investigated in adult men and women constituting a random sample of urban Bantu of Zaire. Blood pressure and the 24-h urinary sodium, potassium, calcium and magnesium averaged 124 +/- 20/72 +/- 14 mmHg, 87 +/- 51 mmol, 33 +/- 19 mmol, 828 +/- 91 mumol and 1.9 +/- 1.6 mmol, respectively. After adjusting for sex, age, body weight and pulse rate, systolic pressure was significantly and positively correlated with urinary sodium in all subjects and in women taken separately; it was also negatively correlated with urinary potassium, while diastolic pressure was weakly associated with urinary calcium. When instead of the 24-h urinary sodium and potassium the sodium: potassium ratio was considered as an independent variable in multiple regression analysis, it was correlated with both systolic and diastolic pressure. Our results indicate that age, body weight, pulse rate, sex and the sodium: potassium ratio contribute to the prediction of systolic and diastolic blood pressure, while urinary calcium was only associated with diastolic pressure.

Adult↗
PubMed1986

Chronic treatment with tibalosine in essential hypertension.

UNLABELLED: After a run-in period on placebo, 26 patients with essential hypertension were prescribed single-blind tibalosine, 150 mg daily. On tibalosine their blood pressure decreased from 157/101 to 147/93 mm Hg (p less than 0.001) and their heart rate from 74 to 68 beats per minute (p less than 0.01), while plasma renin activity tended to fall from 0.81 to 0.65 ng/ml/hr (p = 0.06). Twelve patients, maintained on monotherapy with tibalosine for an average of 3.8 months, kept a diastolic pressure below 90 mm Hg. Ten patients, whose diastolic pressure on tibalosine alone remained equal to or higher than 90 mm Hg were continued on this drug for 6.6 months, but were additionally given in a double-blind and randomized way either placebo, or atenolol 100 mg, or chlorthalidone, 50 mg, daily. As compared to tibalosine plus placebo, blood pressure and heart rate decreased further on tibalosine plus atenolol from 148/97 to 140/90 mm Hg (p less than 0.05) and from 70 to 60 beats per minute (p less than 0.05), respectively. The additional blood pressure lowering effect of tibalosine plus chlorthalidone to a level of 143/96 mm Hg was not statistically significant. Eight of 10 patients' blood pressure responded better to tibalosine combined with atenolol than with chlorthalidone. Because of adverse reactions tibalosine was discontinued in 8 of the 26 patients (31%), namely in 4 who prematurely dropped out from the study and in another 4 patients, who remained adherent to the protocol. Somnolence, weary legs and dry mouth were reported more frequently (p less than 0.05) on tibalosine than on placebo. IN CONCLUSION: tibalosine is an effective anti-hypertensive drug, but side effects preclude its clinical use at a daily dose of 150 mg; the combination with a beta-adrenoceptor blocking drug seems therapeutically more effective than with a thiazide.

Adult↗
PubMed1986

Sodium and potassium fluxes and concentrations in erythrocytes of normal subjects during prolonged sodium depletion and repletion.

The erythrocyte concentration and fluxes of sodium and potassium were investigated in normal white male subjects during dietary sodium restriction and repletion, each period lasting for 16 weeks. During dietary sodium restriction the intra-erythrocyte sodium concentration decreased and the red cell ouabain-sensitive 86Rb-uptake increased; no significant changes were observed in the ouabain-insensitive fluxes of sodium such as the total, frusemide-resistant and frusemide-sensitive Na+-efflux and the Na+, Li+-countertransport. The decrease in the intra-erythrocyte sodium concentration could result from an increased Na+,K+-ATPase pump activity. The latter increase could be secondary to the early decrease in a digitalis-like plasma inhibitor and the late increase could be facilitated by the late rise in the intracellular ATP concentration, which is the energy supplier for this pump. During the subsequent first month of sodium repletion the intra-erythrocyte sodium concentration remained low, the red cell ouabain-sensitive 86Rb-uptake and ATP concentration remained elevated and returned to baseline only after 16 weeks. This long-term effect suggests either the involvement of a mechanism which can only be slowly reversible or a mechanism which is irreversible so that normalization takes place only when new red cells are released into the circulation.

Adult↗
PubMed1985

Intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal men and women.

The intracellular concentration and transmembrane fluxes of sodium and potassium were studied in the red blood cells of normal men and women in the two halves of their menstrual cycle. Compared to men, the intra-erythrocyte sodium concentration was lower in women during the second half of the menstrual cycle. These two groups were similar for Na+, K+-ATPase pump activity estimated from the ouabain-sensitive 86rubidium-uptake and for the furosemide-sensitive sodium and potassium efflux. Women in the first half of the menstrual cycle, had intra-erythrocyte sodium concentration similar to men, but their furosemide-sensitive sodium efflux was lower. A lower intra-erythrocyte sodium concentration was observed in the second half as compared to the first half of the menstrual cycle in women. No significant difference was observed in the intra-erythrocyte potassium concentration and transmembrane fluxes of potassium in men and women in either half of the menstrual cycle. Therefore one should take into account sex-related variability when studying cationic fluxes and concentrations in red blood cells of men and women.

Adult↗
PubMed1985

Familial aggregation of blood pressure, anthropometric characteristics and urinary excretion of sodium and potassium--a population study in two Belgian towns.

Blood pressure and anthropometric characteristics were measured on two separate occasions and the urinary sodium and potassium excretion determined from one 24-hr urine collection in a random population sample (n = 612) of two Belgian towns. After adjusting for confounding factors familial aggregation of these measurements was studied by computing correlation coefficients for the various intrafamilial relationships. Spouses are genetically dissimilar and share a common home environment only from adulthood on. The spouse-spouse correlations for blood pressure, body weight, body mass index and urinary sodium were therefore not significant, whereas the close spouse-spouse correlation for height (r = 0.29) may be explained by assortive marriage. Sibs not only share a common home environment, but also part of their genetic material. Significant sib-sib correlations could therefore be demonstrated for diastolic blood pressure (r = 0.21), height (r = 0.32), body mass index (r = 0.24) and urinary sodium (r = 0.34). For systolic pressure the father-son (r = 0.33) and mother-daughter (r = 0.24) correlations were significant, whereas the other parent-offspring correlations for systolic and diastolic pressure were not statistically different from zero. The tendency of the correlation coefficients for body weight and body mass index to be higher in mother-offspring than in father-offspring pairs suggests a closer maternal role in the determination of calorie intake in offspring. The parent-offspring correlations for urinary sodium were only significant in father-daughter (r = 0.24) and mother-son (r = 0.21) pairs. The fact that potassium, in contrast to sodium, is rarely used as an artificial additive in food preparation may explain why the correlations for urinary potassium were relatively high in all relationship pairs, varying from 0.20 to 0.34.

Adolescent↗
PubMed1985

Effects of ketanserin on the intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal male subjects.

The effect of acute and short-term administration of ketanserin on the intracellular concentrations and transmembrane fluxes of sodium and potassium was studied in erythrocytes of 12 sodium-replete normal male subjects. The subjects received 40 mg ketanserin three times a day for 1 week. Blood samples were drawn before and 1.5 h after the first dose, 12 h after the evening dose of the 6th day, and 1.5 h after the morning dose of the 7th day. The intraerythrocyte sodium concentration was not changed after the first dose of ketanserin, but was decreased during short-term treatment with ketanserin. The ouabain-sensitive 86Rb-uptake, an estimate of the Na+,K+-adenosine triphosphatase pump activity, was decreased after acute ketanserin administration, but not during short-term treatment. This change in intraerythrocyte sodium concentration was related to the change in ouabain-sensitive 86Rb-uptake. The red cell Na+,K+-cotransport and Na+,Li+-countertransport transport activity were not changed during acute and short-term administration of ketanserin. These results indicate that short-term ketanserin administration decreases the intraerythrocyte sodium concentration, but the flux measurements can not explain this observation.

Cell Membrane Permeability↗
PubMed1985

Hemodynamic response to chronic ketanserin treatment in essential hypertension.

Ketanserin (120 mg/day) or placebo was given orally to 14 patients with mild to moderate essential hypertension according to a double-blind crossover protocol, each treatment period lasting 6 weeks. Resting intraarterial pressure in the recumbent position was reduced from 150/84 to 141/77 mm Hg; the hypotensive effect persisted throughout an uninterrupted graded exercise test to the point of exhaustion. The hemodynamic effects were similar at rest and during exercise. Overall, systemic vascular resistance decreased by 14%, heart rate fell by 5%, but stroke volume and cardiac output increased. The pressor responses to methoxamine and to phenylephrine were reduced by ketanserin.

Adult↗
PubMed1985

Double-blind comparison of ketanserin with propranolol in hypertensive patients: interim report.

This double-blind study, which is still in progress, aims to compare ketanserin (K) and propranolol (P) during long-term treatment of hypertensive patients in general practice. After a run-in period on placebo, active treatment was initiated with 20 mg K or 40 mg P, b.i.d., during a 2-week period, whereafter the daily dose of either drug was doubled. Presently, 331 patients have been randomized, two-thirds to the K group (n = 221) and one-third to the P group (n = 110). Both groups were similar at randomization, with blood pressure (BP) averaging 171/105 mm Hg. The presently available data concerning the initial 3 months of the trial show that up to the 2nd month after randomization, systolic BP was significantly (p less than 0.05) higher in the K than in the P group, whereas the differences in diastolic BP were mostly not significant. The change in BP after 3 months on K treatment was positively and independently related to both the initial BP and the concurrent changes in body weight. Heart rate was lower (p less than 0.001) during P, whereas body weight was not statistically different between both groups. Differences in complaints between the K and P group were small. However, in the K group dry mouth was transiently more frequently reported at 1 month (p = 0.02) and multiple complaints at 3 months (p = 0.03).

Adult↗
PubMed1985

Active and acid-activable inactive renin during inhibition by indomethacin of prostaglandin synthesis in sodium-replete man.

The effect of inhibition of prostaglandin synthesis by indomethacin on active renin and on acid-activable inactive renin was studied in nine healthy, sodium-replete men, both at rest and exercise. These volunteers were investigated after pretreatment with placebo or indomethacin, 150 mg daily for 3 days. Indomethacin induced a decrease in active (P = 0.004), total (P less than 0.001) and inactive (P = 0.02) renin at rest recumbent and at rest, sitting. Inhibition of prostaglandins with indomethacin reduced (P less than 0.001) active and total renin at each level of work load but not (P = 0.32) inactive renin. However the exercise-induced stimulation (P less than 0.05) of active and of total renin still occur during indomethacin. Indomethacin reduced (P less than 0.001) at rest, sitting and at maximal exercise the plasma concentrations of immunoreactive prostaglandins E2, prostaglandin F2 alpha and 13, 14-dihydro-15-keto-prostaglandin F alpha; the urinary excretion of immunoreactive prostaglandin E2 and F2 alpha were also reduced.

Adult↗
PubMed1985

Plasma levels of renin, angiotensin II, and 6-ketoprostaglandin F1 alpha in endurance athletes.

Twelve male runners and 12 matched nonathletes performed a prolonged uninterrupted graded exercise test on the bicycle ergometer up to exhaustion to study blood pressure and plasma levels of renin (PRA), vasoconstrictor angiotensin II (ANG II), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), a metabolite of the vasodilator prostacyclin. In the athletes work load was increased by 30 W/4 min, and in the control subjects the increments of work load were adjusted to their lower exercise capacity to equalize total exercise duration. Blood was drawn, and blood pressure and O2 uptake (VO2) were measured at rest and at the fourth, eighth, and last steps of exercise. Peak VO2 averaged 60 +/- 1.6 ml . min-1 . kg-1 in the runners and 46.8 +/- 1.5 in the nonathletes. To evaluate differences between athletes and controls, PRA, ANG II, and 6-keto-PGF1 alpha were first adjusted for significant confounding factors, such as age, weight, hematocrit, 24-h urinary sodium excretion, and O2 uptake. PRA was significantly lower in the athletes (F = 11.2; P less than 0.01); ANG II was not different at rest, but its rise with exercise was less steep in the runners (F = 8.2; P less than 0.01), whereas 6-keto-PGF1 alpha was not different between the groups (F = 1.3; NS). Despite the differences in PRA and ANG II, however, blood pressure was similar in athletes and nonathletes (F = 0.0; NS).

6-Ketoprostaglandin F1 alpha↗
PubMed1985

The nature of opioid involvement in the hemodynamic respiratory and humoral responses to exercise.

After 30 min rest in the lying position, 12 healthy male volunteers (average age 22 years) received, in a randomized double-blind cross-over protocol, either saline or naloxone (10 mg iv followed by a continuous infusion of 10 mg/hr). Thereafter they rested for a further 30 min in the recumbent position and for 15 min sitting on a bicycle ergometer; they then exercised to exhaustion. At rest plasma levels of adrenocorticotropin (ACTH), cortisol, and aldosterone increased during infusion of naloxone, while body temperature decreased. During exercise the difference in plasma ACTH between naloxone and saline periods was abolished, while the differences in plasma cortisol and aldosterone lost statistical significance. Intra-arterial pressure, heart rate, ventilation, O2 uptake, and CO2 output were continuously monitored throughout the experiment and were not affected by naloxone. This was also the case for several hormonal and biochemical measurements, including those of plasma renin, angiotensin II, norepinephrine, 13,14-dihydro-15-keto-prostaglandin F2 alpha, glucose and lactate, and serum insulin and growth hormone. Exercise performance was not changed by naloxone. In conclusion (1) during exhaustive graded exercise of short duration opioidergic inhibition of the pituitary-adrenocortical axis is probably not sustained, (2) apart from the latter mechanism, the present study does not support the hypothesis that endogenous opioids are involved in various hemodynamic, respiratory, and hormonal responses to this type of exercise.

Adult↗
PubMed1985

Ketanserin: a new hypotensive drug?

The possible use of ketanserin for the chronic treatment of patients with essential hypertension was discussed based on the data exposed at this symposium. Its hypotensive effect is established during placebo controlled trials, but more data are needed to determine its relative potency compared to standard hypotensive drugs. The drug seems to act by reducing systemic vascular resistance, but the relative role of the serotonin and alpha inhibition in the chronic hypotensive effect in man is not yet known. Subjective side effects occur after the first dose, but seem to be less frequent during chronic treatment; organ toxicity has not been reported in the therapeutic doses. The drug could be particularly indicated in elderly hypertensive patients, especially in those with peripheral vascular disease. The influence on morbidity and mortality is not yet known.

Animals↗
PubMed1985

Intra-erythrocyte concentration and transmembrane fluxes of sodium and potassium during acute and short-term administration of ketanserin in normal male subjects.

The effect of acute and short-term administration of ketanserin on the intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes was studied in 12 sodium-replete, normal male subjects. The subjects received 40 mg ketanserin three times a day for one week. Blood samples were drawn before and 2.5 hours after the first dose, 12 hours after the evening dose of the sixth day and 1.5 hours after the morning dose of the seventh day. The intra-erythrocyte sodium concentration was not changed following the first dose of ketanserin, but was decreased (p less than 0.05) during short-term treatment with ketanserin. The ouabain-sensitive 86Rb-uptake, an estimate of the Na+,K+-ATPase pump activity, was decreased (p less than 0.001) after acute ketanserin administration, but not (p = 0.07) during short-term treatment. This change in intra-erythrocyte sodium concentration was related (r = 0.73, p less than 0.01) to the change in ouabain-sensitive 86Rb-uptake. The red cell Na+,K+-cotransport and Na+,Li+-countertransport activity were not changed during acute and short-term administration of ketanserin. The results indicate that short-term ketanserin administration decreases the intra-erythrocyte sodium concentration, but the flux measurements cannot explain this observation.

Adult↗
PubMed1985

Relationship between carotid baroreflex sensitivity, physical fitness and activity in cyclists.

Carotid baroreceptors were stimulated with neck suction in 24 cycling tourists and pulse interval lengthening was measured. Eight intensities of neck chamber suction were applied to select a criterion for computing the RR response that gives a significant linear relationship with the magnitude of the stimuli in the highest number of individuals. The best criterion was the maximal RR prolongation within 5 s after the onset of the stimulus. The slope of this relationship was defined as baroreflex sensitivity. Baroreflex sensitivity averaged 7.3 +/- 0.8 ms/mmHg. The cycling tourists underwent an exercise test on a bicycle ergometer until exhaustion, and oxygen uptake, pulmonary ventilation, peak heart rate and exercise duration were determined. In single and multiple regression analysis, baroreflex sensitivity was not significantly related to basal heart rate, peak oxygen uptake and ventilation, duration of exercise or other training characteristics. The results suggest that in man the so-called sensitivity of the carotid baroreflex control of heart rate is not influenced by the level of physical fitness and therefore the measurement of these characteristics can be neglected in evaluating baroreflex sensitivity.

Adolescent↗
PubMed1985

Differential responses of plasma aldosterone, cortisol and adrenocorticotropin to two dopamine receptor antagonists.

The response of plasma aldosterone, cortisol and adrenocorticotropin (ACTH) to the dopamine antagonists metoclopramide and domperidone, administered intravenously in a dose of 1 mg/kg, was investigated in healthy volunteers. Within 15 min after metoclopramide administration, plasma aldosterone (+ 99%), cortisol (+ 75%) and ACTH (+ 55%) increased (p less than 0.001), whereas the plasma levels of these hormones were not altered after domperidone. The differential responses of plasma aldosterone and cortisol to high doses of metoclopramide and domperidone are therefore, at least partially, mediated via the enhanced adrenal stimulation by ACTH after metoclopramide.

Adrenocorticotropic Hormone↗