[Physical exercise and arterial hypertension].
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
B Waeber
Publications and source records attributed to B Waeber.
[Diagnostic assessment of hypertensive patients].
Explore the source record for details and available documents.
Adrenal Gland Neoplasms↗
[Atrial natriuretic factor in man: physiopathological implications].
Explore the source record for details and available documents.
Aldosterone↗
Clinical applications of antimineralocorticoids.
The renin-angiotensin-aldosterone system plays an important role in the development and maintenance of high blood pressure in several forms of hypertension. In hypertensive patients with primary aldosteronism, antimineralocorticoids are, as expected, very effective in reducing blood pressure and correcting metabolic disturbances. In patients with essential hypertension, an abnormal relationship between angiotensin II and aldosterone can occur. Aldosterone secretion in these patients is often too high relative to circulating levels of angiotensin II. Antimineralocorticoids effectively lower blood pressure in a large number of these patients. The reactive hyperreninemia caused by salt depletion is a factor limiting the antihypertensive effect of natriuretic agents including that of antimineralocorticoids. The enhanced aldosterone secretion resulting from treatment with a diuretic other than an antimineralocorticoid may diminish the natriuretic action of that diuretic. Therefore, antimineralocorticoids given in addition to a diuretic enhance natriuresis. The renin-angiotensin-aldosterone system is also involved as a compensatory mechanism in cardiovascular and body fluid homeostasis of patients with severe congestive heart failure or liver cirrhosis with ascites. Antimineralocorticoids are very effective in such conditions. In patients with congestive heart failure treated with digitalis, these natriuretic agents are particularly useful because of their potassium-sparing properties. The risk of developing hyperkalemia during antimineralocorticoid administration is negligible unless renal function is impaired. Antimineralocorticoids have the advantage of exerting no deleterious effect on carbohydrate and lipid metabolism. The use of these agents seems therefore rational in a variety of diseases concerned with blood pressure and body fluid volume regulation.
Aldosterone↗
In vitro renin inhibition to prevent generation of angiotensins during determination of angiotensin I and II.
To prevent in vitro generation of angiotensins, the renin inhibitor CGP 29287 (CGP) was added to blood sampling tubes. Plasma immunoreactive angiotensin (ir-ANG) I and II were simultaneously measured by radioimmunoassay after rapid and quantitative extraction from a single plasma sample on phenylsilylsilica (Bondelut PH). True plasma ANG-(1-8)octapeptide was determined after additional separation of the different angiotensins by high performance liquid chromatography. Ir-ANG II/CGP showed the known linear relationship with ANG-(1-8)octapeptide (r = 0.87, n = 23), but - in contrast to studies without addition of CGP - the y-axis intercept which presumably represents cross-reacting angiotensins other than ANG II was very small. Ir-ANG II/CGP concentrations fell below 1 fmol/ml after converting enzyme inhibition. The results suggest that CGP 29287 prevents in vitro generation of ANG I and ANG II as well as the ANG-metabolites. Ir-ANG I/CGP measured after Bondelut PH extraction of the plasma was strongly correlated with ir-ANG I obtained after blood ethanol extraction (r = 0.97, n = 23). Thus, it is now possible to measure reliably both ANG I and ANG II within the same plasma extract after a simple extraction procedure.
Angiotensin I↗
Cardiovascular effects of neuropeptide Y.
Neuropeptide Y (NPY) is present in the brain, the adrenal medulla, and peripheral sympathetic nerves. This peptide is released together with catecholamines during sympathoadrenal activation. It possesses direct vasoconstrictor properties that are not dependent on simultaneous adrenergic activation. Moreover, it potentiates the vascular effect of several stimulatory substances and may contribute to the modulation of blood pressure responsiveness under a number of circumstances. NPY may also be indirectly involved in the control of blood pressure through regulating the release of hormones with well-established actions on the cardiovascular system.
Adrenal Medulla↗
Comparison of betaxolol with verapamil in hypertensive patients: discrepancy between office and ambulatory blood pressures.
The purpose of this study was to compare in the individual hypertensive patient the blood pressure lowering effect of a beta-blocking agent i.e. betaxolol with that of a calcium entry blocker, i.e. verapamil. The antihypertensive efficacy of the drugs was evaluated both at the physician's office and by monitoring ambulatory daytime blood pressure using a portable blood pressure recorder (Remler M2000). Seventeen patients with uncomplicated essential hypertension (aged 35-67 years) were treated for two consecutive 6-week periods with either betaxolol, 20 mg/day or a slow-release formulation of verapamil, 240-480 mg/day. The sequence of treatment phases was randomly allocated and a 2-week wash-out period preceded each treatment. Both betaxolol and verapamil had a significant blood pressure lowering effect when assessed at the physician's office. However, ambulatory recorded blood pressures were significantly reduced only with betaxolol. In the presence of a physician, the best responders to betaxolol tended to be also the best responders to verapamil, whereas there was no relationship between the fall in ambulatory recorded blood pressure observed during betaxolol and the corresponding fall during verapamil administration. The blood pressure response to both betaxolol and verapamil was not related to age.
Adult↗
Angiotensin II measurement with high-affinity monoclonal antibodies.
Selectivity for the carboxy-terminus of angiotensin II (Ang II) and the high affinity of antibodies are prerequisites for clinical assays that evaluate Ang II in the presence of Ang I. A high-affinity monoclonal antibody (Kd = 7.1 X 10(-11) mol/l) was produced and used for the measurement of plasma Ang II. C3H mice were immunized with Ang II coupled by its carboxy-terminus to thyroglobulin. Somatic cell fusion between spleen cells and SP 2/0 myeloma cells, repeated subcloning and re-injection into mice yielded ascites containing sufficient antibody at a 2 X 10(7)-fold dilution. Radioassay standard curves show 50% tracer displacement when 32 fmol unlabelled Ang II is added and 2 fmol Ang II can be detected. Cross-reactivities, taking the reactivity with Ang II as 1.00 are: Ang I 0.003, Ang (1-7) 0.00001, Ang III 1.05, Ang(3-8) 0.88 and Ang(4-8) 0.75. Fast extraction of angiotensin from 2 ml plasma by reversible adsorption to phenylsilylsilica (Bondelut PH) provides recoveries of 96-102%. During angiotensin converting enzyme inhibition with 25 mg intravenous captopril, plasma immunoreactive Ang II decreased in supine normal volunteers from 8.6 +/- 3.6 to 4.5 +/- 3.4 fmol/ml (P less than 0.01, n = 8). It thus appears that plasma immunoreactive Ang II can now be measured after a simple extraction procedure by using monoclonal antibodies.
Angiotensin II↗
Influence of endogenous bradykinin on acute blood pressure response to vasopressors in normotensive rats assessed with a bradykinin antagonist.
The present study was designed to assess in conscious normotensive rats the influence of various pressor agents on the acute blood pressure response to a bradykinin antagonist (B4162). This antagonist was used at a dose (400 micrograms i.v.) which had been previously shown to block the blood pressure lowering effect of exogenous bradykinin for several minutes. In control rats, the bradykinin antagonist had no effect on blood pressure. However, in rats pretreated with nonpressor doses of angiotensin II or methoxamine or with pressor doses of vasopressin or methoxamine, the same antagonist significantly increased blood pressure by 10 +/- 2.2, 12 +/- 2.7, 9 +/- 1.7, and 16 +/- 3.4 mm Hg, respectively. It therefore appears that circulating bradykinin is not directly involved in blood pressure regulation of conscious normotensive rats. Endogenous bradykinin may however play an important role in blood pressure control by attenuating the pressor effect of angiotensin II, vasopressin, and alpha-adrenoceptor stimulation.
Angiotensin II↗
Plasma angiotensin-(1-8) octapeptide measurement to assess acute angiotensin-converting enzyme inhibition with captopril administered parenterally to normal subjects.
The blood pressure (BP), heart rate (HR), and humoral effects of single intravenous (i.v.) doses of the angiotensin-converting enzyme (ACE) inhibitor captopril was investigated in five normotensive healthy volunteers. Each subject received at 1-week intervals a bolus dose of either captopril (1, 5, and 25 mg) or its vehicle. The study was conducted in a single-blind fashion, and the order of treatment phases was randomized. The different doses of captopril had no acute effect on BP and HR. They induced a dose-dependent decrease in plasma ACE activity and plasma angiotensin II levels. The angiotensin-(1-8) octapeptide was isolated by solid-phase extraction and high-performance liquid chromatography (HPLC) prior to radioimmunoassay (RIA). All three doses of captopril reduced circulating angiotensin II levels within 15 min of drug administration. Only with the 25-mg dose was the angiotensin II concentration below the detection limit at 15 min and still significantly reduced 90 min after drug administration. Simultaneous and progressive decreases in plasma aldosterone levels were observed both with ACE inhibition and during vehicle injection, but the relative fall was more pronounced after captopril administration. No adverse reaction was noticed. These results demonstrate that captopril given parenterally blocks the renin-angiotensin system in a dose-dependent manner. Only with the dose of 25 mg was the inhibition of plasma-converting enzyme activity and the reduction of plasma angiotensin II sustained for at least 1 1/2 h.
Adult↗
Effect of ganglion blockade with pentolinium on circulating neuropeptide Y levels in conscious rats.
The vasoconstrictor peptide, neuropeptide Y (NPY), is present in perivascular noradrenergic neurons of all mammals studied and may be important in the regulation of blood pressure. High plasma levels of NPY have been measured in the rat. To investigate partially the source and factors controlling the release of the circulating peptide, the effect of pentolinium tartrate administration has been studied in conscious rats. Pentolinium given as a bolus (5 mg/kg) followed by an infusion of a further 5 mg/kg/30 min produced a highly significant reduction in blood pressure of more than 40 mm Hg, when compared to either basal values or control animals treated with saline. Pentolinium treatment resulted in significantly lower plasma neuropeptide Y levels (31.0 +/- 6.7 fmol/ml) compared with those of control animals (78.6 +/- 8.2 fmol/ml). Circulating catecholamines were also significantly reduced in those animals receiving pentolinium. These results are compatible with circulating NPY arising from the sympathetic nervous system, with release being controlled by the mechanisms already established for catecholamines.
Animals↗
Atrial natriuretic peptide administered as intravenous infusion or bolus injection to patients with liver cirrhosis and ascites.
The effect of a synthetic atrial natriuretic peptide (h-ANP, 25 amino acids, Wy-47.663) on blood pressure, renal electrolyte excretion, plasma catecholamines, and plasma renin activity was studied in nine patients with cirrhosis of the liver and ascites. The peptide was infused intravenously at 24-h intervals for 2 h in groups of four patients each in two different doses (0.015 and 0.075 micrograms/kg/min or 0.06 and 0.3 micrograms/kg/min). A control experiment with the vehicle was performed in all patients. In three patients h-ANP (1 and 2 micrograms/kg i.v.) was administered as an intravenous bolus injection. Consistent falls in blood pressure were observed during h-ANP infusion only with the two higher doses. The two lower infused doses induced a consistent natriuresis; this renal response was abolished when the two larger doses were used. When given as a bolus, h-ANP had a natriuretic effect comparable to that of the two lower doses of infused h-ANP. Plasma catecholamines and plasma renin activity increased during infusion of the two higher doses of h-ANP. It thus appears that in patients with cirrhosis and ascites, the natriuretic effect of infused h-ANP decreases rather than increases when the doses are raised. Bolus administration of h-ANP may be less prone to trigger counterbalancing responses and side-effects.
Adult↗
Infusion of atrial natriuretic peptide to patients with congestive heart failure.
Atrial natriuretic peptides (ANP) exert vasodilating and natriuretic actions. The present study was undertaken to test the effect of low dose infusions of synthetic ANP on hemodynamic and humoral variables of patients with severe heart failure. Eight patients, aged 26 to 71 years, with severe congestive heart failure due to ischemic heart disease or idiopathic dilated cardiomyopathy were included in the study. Synthetic human (3-28) ANP was infused at doses ranging from 0.5 to 2 micrograms/min for up to 3 h. Pulmonary capillary wedge pressure fell from 24 +/- 1 to 16 +/- 2 mm Hg (mean +/- SEM) (p less than 0.01) and cardiac index tended to rise from 2 +/- 0.2 to 2.3 +/- 0.2 L/min/m2 (NS), while blood pressure and heart rate did not change. One patient experienced a marked drop in pulmonary capillary wedge and arterial blood pressure that necessitated the administration of saline. ANP infusion did not alter plasma renin activity or plasma aldosterone, norepinephrine, or vasopressin levels. It decreased plasma epinephrine levels from 0.472 +/- 0.077 to 0.267 +/- 0.024 nmol/L (p less than 0.05). Plasma ANP levels were markedly elevated in all patients before initiating the infusion. They had no predictive value for the hemodynamic response to exogenous ANP. No correlation was observed between the hemodynamic effects of ANP and those induced by the subsequently administered converting enzyme inhibitor captopril, which seemed to improve cardiac function more consistently.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Calcium entry blockade attenuates the acute blood pressure rise induced by cigarette smoking.
The purpose of this study was to assess whether the administration of a calcium entry blocker can prevent the acute blood pressure rise induced by cigarette smoking. Seven male habitual smokers were included. After 45 min of equilibration, they took in randomized single-blind fashion at a 1 week interval either a placebo or nifedipine, 10 mg p.o. Thirty minutes thereafter, the subjects smoked within 10 min two cigarettes containing 1.4 mg of nicotine each. In addition to heart rate and skin blood flow (laser Doppler method), blood pressure of the median left finger was monitored continuously for 100 min using a noninvasive device (Finapres). Nifedipine induced an increase in skin blood flow that was not influenced by smoking. This skin blood flow response was observed although nifedipine had by itself no effect on systemic blood pressure. The calcium antagonist markedly attenuated the blood pressure rise induced by cigarette smoking. However, it tended to accentuate the heart rate acceleration resulting from inhalation of nicotine-containing smoke.
Adult↗
Hemodynamic, renal, and endocrine effects of 4-h infusions of human atrial natriuretic peptide in normal volunteers.
A synthetic human atrial natriuretic peptide of 26 aminoacids [human (3-28)ANP or hANP] was infused into normal male volunteers. Six subjects were infused for 4 h at 1-wk intervals with either hANP at the rate of 0.5 or 1.0 microgram/min or its vehicle in a single-blind randomized order. Human (3-28)ANP at the dose of 0.5 microgram/min raised immunoreactive plasma ANP levels from 104 +/- 17 to 221 +/- 24 pg/ml (mean +/- SEM), but it induced no significant change in blood pressure, heart rate, effective renal plasma flow, glomerular filtration rate, or renal electrolyte excretion. At the rate of 1.0 microgram/min, human (3-28)ANP increased immunoreactive plasma ANP levels from 89 +/- 12 to 454 +/- 30 pg/ml. It reduced effective renal plasma flow from 523 +/- 40 to 453 +/- 38 ml/min (P less than 0.05 vs. vehicle), but left glomerular filtration rate unchanged. Natriuresis rose from 207 +/- 52 to 501 +/- 69 mumol/min (P less than 0.05 vs. vehicle) and urinary magnesium excretion from 3.6 +/- 0.5 to 5.6 +/- 0.5 mumol/min (P less than 0.01 vs. vehicle). The excretion rate of the other electrolytes, blood pressure, and heart rate were not significantly modified. At both doses, human (3-28)ANP tended to suppress the activity of the renin-angiotensin-aldosterone system. In 3 additional volunteers, the skin blood flow response to human (3-28)ANP, infused for 4 h at the rate of 1.0 microgram/min, was studied by means of a laser-doppler flowmeter. The skin blood flow rose during the first 2 h of peptide administration, then fell progressively to values below baseline. After the infusion was discontinued, it remained depressed for more than 2 h. Thus, in normal volunteers, human (3-28)ANP at the dose of 1.0 microgram/min produced results similar to those obtained previously with rat (3-28)ANP. It enhanced natriuresis without changing the glomerular filtration rate while effective renal plasma flow fell. It also induced a transient vasodilation of the skin vascular bed.
Adult↗
Effects of nonhypotensive endotoxemia in conscious rats: role of prostaglandins.
A nonhypotensive dose of endotoxin was administered to normal conscious rats to evaluate the vascular and humoral effects of endotoxemia per se. Mean blood pressure and heart rate remained stable during the 45 min infusion of Escherichia coli endotoxin (0.01 mg/min). However, a marked increase in plasma renin activity (4.2 +/- 0.48 vs. 30.2 +/- 6 ng.ml-1.h-1, mean +/- SE, P less than 0.01), plasma epinephrine (0.112 +/- 0.04 vs. 1.71 +/- 0.5 ng/ml, P less than 0.01), and plasma norepinephrine (0.269 +/- 0.028 vs. 1.3 +/- 0.2 ng/ml, P less than 0.001) was observed during infusion in endotoxin-treated rats when compared with the vehicle-treated animals. In addition, the blood pressure response to exogenous norepinephrine was significantly reduced during nonhypotensive endotoxemia. Significant changes in regional blood flow distribution, as assessed by radiolabeled microspheres, were observed in endotoxemic rats; in particular a decrease in renal blood flow (7.39 +/- 0.43 vs. 5.97 +/- 0.4 ml.min-1.g-1, P less than 0.05) and an increase in coronary blood flow (5.01 +/- 0.38 vs. 6.44 +/- 0.33 ml.min-1.g-1, P less than 0.01) were found. The role of prostaglandins in the vascular and humoral alterations induced by nonhypotensive endotoxemia was also examined. Pretreatment with indomethacin (5 mg) prevented the increase in plasma renin activity as well as plasma catecholamine levels. On the contrary, the decreased vascular reactivity and the reduction in renal blood flow observed during endotoxemia were not affected by prostaglandin synthesis inhibition. Thus significant vascular and humoral changes have been found during endotoxemia even in absence of hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Effect of sodium intake on gene expression and plasma levels of ANF in rats.
The effect of short- and long-term sodium loading and sodium restriction on the gene expression as well as on circulating plasma levels of atrial natriuretic factor (ANF) was evaluated in normotensive Wistar rats. These rats were fed either a low-, a regular-, or a high-sodium diet (regular diet and 1% saline as drinking fluid) and studied after 1 and 3 wk. The ANF mRNA was determined in pooled atria and ventricles of the different groups of rats, using the dot-blot technique. Plasma ANF levels were measured with a radioimmunoassay. After 1 wk on the high-sodium diet, ANF mRNA was increased in right atria and ventricles together with circulating ANF levels when compared with animals maintained for the same period on a low-sodium diet. After 3 wk on the various diets, the differences in cardiac ANF mRNA and in plasma ANF levels had disappeared. Gene expression of ANF was also looked for in different areas of the brain, lung, thyroid, adrenals, and the kidney; no hybridization was detected in any of these organs. These data suggest that in rats, the transcription of the ANF gene and peptide release in enhanced only during short-term adaptation to dietary sodium loading.
Animals↗
Response of atrial natriuretic peptide to acute saline loading in essential hypertension.
To further investigate the mechanism(s) of the exaggerated natriuretic response of hypertensives to volume expansion (VE; 1,800 ml iv isotonic saline over 3 h), the plasma levels of immunoreactive atrial natriuretic peptide (ANP) were measured in 11 normal subjects (NT) and 12 patients with mild essential hypertension (HT). NT and HT groups were similar with respect to age and basal levels of renin, aldosterone and ANP (34.5 +/- 5.5 in NT and 32.5 +/- 6.3 pg/ml in HT, mean +/- SE). In response to VE, ANP increased to the same extent in both groups (a change of 19.3 +/- 5.2 in NT and of 22.2 +/- 7.1 pg/ml in HT) despite the finding of an exaggerated natriuretic response to VE in essential hypertension (36 +/- 3.5 in NT and 54.9 +/- 6.3 nmol/3 h in HT, P less than 0.02). In addition, the fall in hematocrit and serum protein associated with saline infusion was less marked in HT than NT. The change in ANP induced by VE was inversely correlated with the percent fall in hematocrit and the increment in the fractional excretion of sodium in both groups. These observations suggest that ANPs may participate in the control of the renal response to isotonic VE; however they do not support an unequivocal influence of ANP in the exaggerated natriuretic response to VE of patients with essential hypertension.
Adult↗