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Biomedical subjects

R Fagard

Publications and source records attributed to R Fagard.

At least 325 records · Page 18Linked to original sources
PubMed1987

Plasma renin system during exercise in normal men.

The exercise-related increase in plasma renin activity (PRA) and in the plasma concentration of angiotensin II (ANG II) and aldosterone (Aldo) was studied in 43 healthy volunteers whose 24-h urinary sodium excretion (UVNa) ranged from 10 to 250 mmol. Arterial blood samples were obtained at rest and during bicycle ergometry. Compared with rest, PRA, ANG II, and Aldo rose to a similar extent during light and moderate exercise. However, at peak exercise ANG II increased significantly more (P less than 0.001) than PRA and Aldo. Thus, with increasing intensity of exercise, the slope of the linear regression of ANG II on PRA became significantly (P less than 0.001) steeper, whereas at maximal exercise the Aldo response did not follow the acute rise in ANG II. At rest as well as during exercise, Aldo rose with increasing ANG II, but the stimulatory effect of ANG II on Aldo was attenuated with higher sodium intake, as estimated from UVNa. Finally, independent of the level of physical activity, UVNa was negatively correlated with PRA, ANG II, and Aldo.

Adult↗
PubMed1987

Plasma atrial natriuretic peptide and cyclic nucleotide levels before and after a marathon.

Plasma alpha-atrial natriuretic peptide (alpha-ANP) concentration and levels of cyclic nucleotides [guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP)] were studied in 23 runners before and after a marathon race. Blood samples were drawn from an antecubital vein the morning before the race (base line), at 3 P.M. (i.e., 2 h before the start), on arrival, and 12 and 36 h and 7 days later. Compared with the base-line values of plasma alpha-ANP (5 pmol/l), cGMP (3.8 nmol/l), and cAMP (15.8 nmol/l), the plasma levels of alpha-ANP, cGMP, and cAMP were increased immediately after the marathon, respectively, to 12.0 pmol/l, 12.7 nmol/l, and 50.5 nmol/l. The increase in the plasma alpha-ANP concentration was related (r = 0.85; P less than 0.001) to the changes in plasma cGMP, plasma lactate, hematocrit, and body weight. The plasma cGMP and cAMP concentrations had returned to the prerace levels 12 h after the marathon, whereas the plasma alpha-ANP concentration was significantly lower (3.1 pmol/l) than the base-line values and increased above the prerace values 36 h (7.5 pmol/l) and 7 days (6.8 pmol/l) after the marathon. The plasma cGMP level was also higher 36 h (5.4 nmol/l) and 7 days (5.0 nmol/l) after the marathon race.

Adult↗
PubMed1987

Effects of felodipine and metoprolol on blood pressure, plasma renin, angiotensin II, aldosterone and catecholamines in hypertensive patients.

Oral administration of felodipine to 10 patients with mild essential hypertension acutely reduced the brachial artery pressure by 15/13mm Hg. The tachycardia which occurred was sustained for 90 minutes together with an elevated plasma noradrenaline concentration. Addition of intravascular metoprolol after 90 minutes decreased heart rate. The felodipine-induced increase of plasma renin activity (100%; p less than 0.001) was completely reversed by metoprolol. Plasma angiotensin II (PA II) rose by 15% (p less than 0.05) during felodipine, whereas plasma aldosterone concentration was not significantly affected.

Adult↗
PubMed1987

Effects of felodipine on blood pressure and humoral factors in sodium-replete humans at rest and during exercise.

The effect of short-term calcium antagonism with felodipine on blood pressure and on plasma catecholamines, renin, and aldosterone was studied in 10 normal volunteers at rest and during incremental bicycle exercise. At rest, diastolic blood pressure was slightly increased during felodipine treatment, whereas systolic pressure and heart rate were not significantly changed. The plasma noradrenaline concentration and plasma renin activity were increased during felodipine treatment; the plasma adrenaline and aldosterone concentrations, on the contrary, were not significantly changed. The rises in plasma renin activity, plasma aldosterone, and plasma adrenaline and noradrenaline concentrations produced by exercise were not significantly affected by felodipine. It is concluded that the rise in plasma renin activity during calcium antagonism with felodipine is not accompanied by a significant increase in plasma aldosterone. Furthermore, the present data suggest that, at least during exercise, calcium antagonism does not interfere with the mechanisms underlying the exercise-induced activation of renin and aldosterone release.

Adult↗
PubMed1987

Plasma levels of alpha-atrial natriuretic peptide in normal subjects under various postural conditions.

The present paper describes a radioimmunoassay, in conjunction with an extraction procedure on octadecasilyl silica cartridges, of alpha-atrial natriuretic peptide in human plasma and its application in normal subjects under various postural conditions. The sensitivity of this assay is 1.96 pg/ml. The plasma concentrations of alpha-atrial natriuretic peptide in 18 normal male subjects ranged from 10 to 55 pg/ml. This assay was shown to be reproducible as indicated by the low within- and between-assay coefficients of variation. The plasma alpha-ANP concentration decreased during prolonged storage of the plasma at -20 degrees C or -80 degrees C and its level is also lower in hemolyzed plasma samples. The plasma alpha-ANP concentration is similar in standing and supine position but rose significantly when the subjects were tilted 20 degrees head-down.

Aldosterone↗
PubMed1987

ACE-inhibitors in the treatment of elderly hypertensives.

Angiotensin-converting enzyme inhibitors are gaining acceptance as safe and effective agents for treatment of hypertension. Data on their use specifically in elderly hypertensives, however, are limited. Addressed in this review of the available literature are the questions whether they are effective hypotensives in the elderly, whether their effects are age-related, and what effects, if any, do they have on morbidity and mortality in geriatric hypertension.

Aged↗
PubMed1987

Dietary sodium variation, erythrocyte cationic transport and plasma renin-aldosterone in men.

Erythrocyte concentrations 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. Intraerythrocyte sodium concentration decreased and red cell ouabain-sensitive 86Rubidium-uptake increased during dietary sodium restriction while no significant changes were observed in the total, furosemide-resistant and furosemide-sensitive sodium-efflux and the sodium, lithium-countertransport. The decrease in intraerythrocyte sodium concentration could have resulted from the observed increase in sodium, potassium-ATPase pump activity. The latter increase could have been secondary to the early decrease in a digitalis-like plasma inhibitor and the later increase could have been facilitated by the late rise in the intracellular adenosine triphosphate concentration, which is the energy supplier for this pump. During the subsequent first month of sodium repletion intraerythrocyte sodium concentration remained low. Red cell ouabain-sensitive 86Rubidium-uptake and adenosine triphosphate 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↗
PubMed1986

Efficacy of antihypertensive drug treatment according to age, sex, blood pressure, and previous cardiovascular disease in patients over the age of 60.

Results of the European Working Party on High Blood Pressure in the Elderly (EWPHE) trial have been analysed in relation to age, sex, blood pressure, and previous cardiovascular disease. Cardiovascular mortality and the cardiovascular study-terminating events were significantly and independently related to treatment, age, cardiovascular complications at randomisation, and systolic but not diastolic blood pressure. The benefits of treatment observed in the trial seemed to be independent of entry blood pressure and the presence or absence of cardiovascular complications at entry. There was some evidence that treatment effect decreases with advancing age. Little or no benefit from treatment could be demonstrated in patients over the age of 80 years, the great majority of whom were women.

Age Factors↗
PubMed1986

[Physiologic variability of erythrocyte concentrations and transport of sodium and potassium].

Sodium concentrations in erythrocytes are lower in women during the luteal phase of the menstrual cycle than in women studied during the follicular phase and in men. Sodium cotransport activity is lower in women during the follicular phase than in men. Women taking oral contraceptives show no monthly variations in erythrocyte sodium concentrations. Subjects with a family history of essential hypertension have higher sodium concentrations in erythrocytes than those with a different family background, partly because of reduction in sodium cotransport activity. Negroes have marked erythrocyte sodium accumulation due to lower activity of the sodium-potassium pump and cotransport system; they also have reduced sodium-lithium counter-transport. There is no difference between negroes with or without haemoglobin S. There are no changes in erythrocyte potassium concentrations in relation to sex, menstrual phase, race, familial essential hypertension, presence of haemoglobin S or use of oral contraceptives. These physiological variations indicate the factors which must be standardized to study sodium concentrations in cells and sodium transmembrane flux.

Adult↗
PubMed1986

Relative potency of a beta-blocking and a calcium entry blocking agent as antihypertensive drugs in black patients.

The short-term efficacy of nitrendipine (N) as a first stage antihypertensive drug in black patients has been assessed and compared with acebutolol (A) in a double-blind study. Forty patients were randomized and after a 4 week run-in period on placebo, the active treatment was administered for 6 weeks starting with 20 mg N or 200 mg A once daily. The dose was increased up to 60 mg N or 600 mg A as needed. Nitrendipine appeared to be more efficient than acebutolol in reducing blood pressure and the N-induced fall in blood pressure was achieved after 2 weeks. After 2 and 6 weeks on N, the recumbent blood pressure was decreased by 13% and 12% for the systolic and by 14% and 11% for the diastolic pressure. The concurrent decreases in the A group averaged 4% and 5% for the systolic and 5% and 10% for the diastolic pressure after 2 and 6 weeks. Pulse rate and plasma renin activity in the N group were slightly increased and body weight was decreased at the end of the active treatment period.

Acebutolol↗
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

Glucose intolerance during diuretic therapy in elderly hypertensive patients. A second report from the European Working Party on high blood pressure in the elderly (EWPHE).

Five hundred and seven elderly hypertensive patients were followed for 1 year, 371 for 2 years and 270 for 3 years in a double-blind, randomized, controlled trial in which they received either placebo or 25-50 mg hydrochlorothiazide and 50-100 mg of triamterene daily. One third of the active treatment group also received 250 mg to 2 g methyldopa daily. After 1 year the active treatment group had an average increase in fasting blood sugar of 2.5 mg/dl compared with an average fall of 1.4 mg/dl in the placebo group (P = 0.01). The increase in blood sugar 1 hour and 2 hours after 50 g oral glucose tended to be greater in the actively treated group but these increases did not achieve statistical significance. The effects of diuretic treatment were established after one year and did not increase further over the next 2 years. Overall there was an increase in fasting blood sugar of 5 mg/dl in the active treatment group which occurred mainly in the first year. The hyperglycaemic effect of diuretics appeared to be partly or wholly related to potassium loss since, in both groups, impairment of glucose tolerance was most marked in those in whom serum potassium decreased. The measures of blood sugar were also positively related to systolic pressure before and after treatment.

Aged↗
PubMed1986

Beta-adrenoceptors and the regulation of blood pressure and plasma renin during exercise.

The relative role of beta 1- and beta 2-adrenoceptors in the regulation of blood pressure and plasma renin at rest and during exercise was studied in 17 normal male volunteers. They performed, in a randomized order and according to a double-blind crossover study design, three graded and uninterrupted exercise tests until exhaustion after being pretreated during 3 consecutive days with a placebo, with a predominantly beta 1-blocker (atenolol, 50 mg once/day), or with a predominantly beta 2-blocker (ICI 118551, 20 mg 3 times/day). Both drugs caused a decrease of heart rate, but the reduction by ICI 118551 was less pronounced at rest and no additional decline occurred at exercise. ICI 118551 did not affect blood pressure at rest, but during exercise diastolic blood pressure was higher than after a placebo. Atenolol lowered systolic blood pressure at rest and suppressed the exercise-induced increase in systolic blood pressure. At rest and during exercise plasma renin activity was lowered by predominantly beta 1-blockade and unchanged during beta 2-antagonism. The exercise-induced increase in plasma renin was, however, not affected by the beta 1-blocker. After atenolol the urinary excretion of aldosterone was decreased but the plasma aldosterone concentration was not changed. ICI 118551 did not alter plasma or urinary aldosterone. Our results therefore provide further evidence that the adrenoceptors mediating the release of renin at rest and during exercise in humans are partially of the beta 1-subtype, whereas beta 2-adrenergic receptors probably play only a minor role in the control of renin secretion, especially at exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Differentiation of exercise-induced metabolic responses during selective beta 1- and beta 2-antagonism.

The effect of beta 1- or beta 2-antagonism on the plasma levels of glucose, lactate, triglycerides, and free fatty acids was studied in seventeen normal male volunteers. All subjects performed three graded and uninterrupted exercise tests until exhaustion. Prior to each exercise test they received in a randomized order during three consecutive days either placebo or a predominant beta 1-blocker (atenolol, 50 mg once per day) or a predominant beta 2-blocker (ICI 118,551, 20 mg t.i.d.), according to a double-blind cross-over study design. Atenolol increased the plasma level of glucose at rest but did not influence the rise in plasma glucose during exercise. ICI 118,551 did not change the resting plasma glucose level, but it prevented the exercise-induced rise in plasma glucose, observed during placebo. During beta 1-antagonism the plasma lactate concentration at rest and during or after exercise was not different from placebo. During beta 2-blockade the exercise-induced rise in plasma lactate tended to be suppressed, and during recovery the plasma lactate levels were significantly lower than during placebo. The serum triglycerides concentration at rest and exercise was not altered, either by beta 1- or by beta 2-antagonism. Atenolol and ICI 118,551 did not affect the serum level of free fatty acids at rest, but at moderate exercise the serum free fatty acids concentration was lower during beta 1-blockade than during placebo. Our results provide further evidence that beta 2-adrenergic receptors are involved in the regulation of the plasma levels of glucose and lactate during exercise.

Adult↗
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↗