atrial-natriuretic-factor and Hypotension--Orthostatic

Chronic orthostatic hypotension is characterized by recurrent symptoms of cerebral hypoperfusion due to low upright blood pressure levels. The initial approach should be to identify and correct reversible causes. Persistence of orthostatic hypotension suggests autonomic failure. The goal of management is to minimize symptoms and maximize functional capacity; therefore the magnitude of blood pressure fall is not as important as the advent of symptoms. Therapy is based upon the underlying pathophysiology and the risk/benefit ratio of interventions. Patient education and nondrug measures form the cornerstone of management. Drug therapy is often limited by unacceptable supine hypertension. Rational drug use can be governed by individualized trials of therapy. Patients with moderate or severe orthostatic hypotension are difficult to treat, but can be helped toward resumption of a normal life.

Topics: Activities of Daily Living; Atrial Natriuretic Factor; Autonomic Nervous System Diseases; Blood Pressure; Blood Volume; Carbon Dioxide; Clothing; Combined Modality Therapy; Diagnosis, Differential; Drug Therapy, Combination; Fludrocortisone; Hydrogen-Ion Concentration; Hypotension, Orthostatic; Nonprescription Drugs; Patient Education as Topic; Physical Exertion; Posture; Sodium; Weather

The purpose of this study was to ascertain whether abdominal compression with an inflatable abdominal band, a device we developed, improved post-dialytic orthostatic hypotension (OH) in hemodialysis (HD) patients. Twenty-five chronic HD patients with intractable post-dialytic OH were recruited. Post-HD changes in systolic blood pressure (DeltaSBP) in the supine and standing positions were compared in the patients, measured with or without the use of the band. The study showed DeltaSBP after HD without the band was significantly greater than that measured before HD (-36.1+/-18.2 vs -13.1+/-16.8 mm Hg; P<0.0001). DeltaSBP after HD with the band was reduced significantly in comparison to DeltaSBP after HD without the band (-19.4+/-21.2 vs -36.1+/-18.2 mm Hg; P<0.002). Use of the band did not cause an elevation in SBP in the supine position (149.0+/-29.6 vs 155.4+/-25.7 mm Hg); however, it did increase SBP upon standing (129.6+/-27.3 vs 117.2+/-22.6 mm Hg; P<0.05). Eight patients in whom an increase in SBP of 25 mm Hg or more was achieved with the band were classified as responders. Ejection fraction was significantly higher (76.4+/-11.1 vs 61.9+/-13.6%; P<0.02) and atrial natriuretic peptide concentration significantly lower (27.9+/-22.0 vs 68.9+/-47.5 pg/ml; P<0.02) in responders than in non-responders. We conclude that the abdominal band was effective for overcoming post-dialytic OH, without elevating supine SBP in some patients.

Topics: Abdomen; Aged; Aged, 80 and over; Atrial Natriuretic Factor; Blood Pressure; Cardiac Output; Cardiology; Female; Heart Rate; Humans; Hypotension, Orthostatic; Male; Middle Aged; Pressure; Renal Dialysis; Stroke Volume; Supine Position; Urology

Alterations in autonomic function are commonly seen during and after spaceflight, and its ground-based analog, 6 degrees head-down bed rest (HDBR). They may include peripheral vascular regulation, but vasomotor sympathetic efferent nerve discharges to peripheral vasculatures have not been examined. The aim of our study was to examine changes in vasomotor sympathetic nerve activity during HDBR and under orthostasis after HDBR.. We performed 6 d of HDBR on six male subjects, and measured muscle sympathetic nerve activity (MSNA) together with plasma norepinephrine concentrations in the supine position before HDBR and in 6 degrees head-down position on the sixth day (HDBR6) of HDBR. We also measured MSNA in head-up tilt (HUT) test before and after HDBR.. On HDBR6, MSNA burst rate was the same (17+/-4 bursts x min(-1)) as that in supine position before HDBR (15+/-2 bursts min(-1)), but plasma norepinephrine concentrations were decreased to 1.14+/-0.10 pmol x ml(-1) compared with the supine value before HDBR (1.56+/-0.20 pmol x ml(-1), p<0.05). After HDBR, supine MSNA burst rate significantly increased by 58% to 24+/-4 bursts x min(-1). MSNA increment in response to HUT was similar between before (34+/-3 bursts min(-1) x sin HUT(-1)) and after (40+/-6 bursts x min(-1) x sin HUT(-1)) HDBR.. Our findings suggest that: a) the relationship between MSNA and plasma norepinephrine concentrations was altered on the sixth day during HDBR; b) the vasomotor sympathetic nerve activity was enhanced after HDBR; and c) the augmentation of vasomotor sympathetic outflow to muscles under orthostasis was preserved after HDBR.

Topics: Adult; Atrial Natriuretic Factor; Bed Rest; Head-Down Tilt; Heart Rate; Humans; Hypotension, Orthostatic; Male; Norepinephrine; Space Flight; Supine Position; Time Factors; Vasomotor System

Women will be included as mission specialists in the upcoming International Space Station program. This paper describes the changes in volume-regulating hormones and determines the degree of degradation in orthostatic tolerance in a group of women after 120 d of bed rest. The aim of this study was to test a countermeasure program to be used by women during long-duration spaceflights.. For 120 d of -6 degrees head-down bed rest (HDBR), eight healthy women were assigned either to a no-countermeasure (No-CM, n = 4), or to a countermeasure (CM, n = 4) group. In the countermeasure group, exercise began after 2 wk, pharmacological agents were given during the 1st and 3rd mo, and the "Centaur" suit was worn on the last day of bed rest and during the day time for several days after bed rest. Diet supplements were taken during the 1st and 4th mo of HDBR. Tilt tests were run before and after HDBR.. After the HDBR, none of the CM subjects, had pre-syncopal or syncopal symptoms during tilt tests: BP was well maintained in the CM group, while heart rate and BP changed in the No-CM group. In plasma, atrial natriuretic peptide (ANP) increased in both groups and remained high throughout HDBR, while aldosterone increased and remained elevated in the No-CM group. Natriuresis was decreased during HDBR.. The CM protocols used during this study were efficient and prevented orthostatic intolerance for the four CM subjects. It would be necessary to obtain more data regarding this set of CM protocols on female subjects to lead to statistical and formal conclusions.

Topics: Adult; Aldosterone; Arginine Vasopressin; Atrial Natriuretic Factor; Bed Rest; Blood Pressure; Cardiovascular Deconditioning; Exercise Therapy; Female; Head-Down Tilt; Heart Rate; Humans; Hypotension, Orthostatic; Male; Sex Characteristics; Space Flight; Time Factors; Weightlessness Countermeasures; Weightlessness Simulation

The purpose of this study was to determine the effectiveness of a USAF anti-gravity suit (G-suit) on the stability of a patient with chronic orthostatic hypotension.. A 37-yr-old female with a history of insulin-dependent diabetes mellitus (IDDM) and symptomatic orthostasis was evaluated and the results were compared with those of non-diabetic controls, matched for age, height, and weight. Cardiac vagal tone was assessed by determination of standard deviation of 100 R-R intervals (R-R SD). We assessed the carotid-cardiac baroreflex response by plotting R-R intervals (ms) at each of eight neck pressure steps with their respective carotid distending pressures (mm Hg). Heart rate and blood pressure were recorded in response to the Valsalva maneuver (VM) performed at an expiratory pressure of 30 mmHg to assess integrated baroreflex responses. Blood pressures and heart rate were measured during three 5-min stand tests to assess orthostatic responses: a) without G-suit; b) with noninflated G-suit; and c) with inflated G-suit (50 mm Hg).. The IDDM patient had minimal baseline cardiac vagal tone (R-R SD = 8.5 ms) compared with the average response of a control group of 24 subjects with orthostatic stability (R-R SD = 67.2 +/- 7.1 ms). Carotid-cardiac baroreflex response was virtually non-existent in the IDDM patient (Gain = 0.06 ms.mm Hg-1) compared to the control subjects (4.4 +/- 0.8 ms.mm Hg-1). VM responses corroborated the lack of cardiac baroreflex response in the IDDM patient, while blood pressure changes during the VM were similar to those of the controls. Upon standing, the IDDM patient demonstrated severe orthostatic hypotension (90 mm Hg SBP) and tachycardia without the G-suit. The G-suit, with and without pressure, reduced hypotension and tachycardia during standing.. These results demonstrate successful application of Air Force technology as a useful alternative to pharmacologic intervention in the treatment of a patient with autonomic dysfunction leading to supine hypertension and orthostatic hypotension.

Topics: Adult; Aerospace Medicine; Arginine Vasopressin; Atrial Natriuretic Factor; Baroreflex; Diabetic Angiopathies; Female; Fluid Shifts; Gravity Suits; Heart Rate; Humans; Hypotension, Orthostatic; Norepinephrine; Plasma Volume; Renin; Valsalva Maneuver; Vasomotor System

Midodrine, a peripheral alpha-adrenergic agonist, was evaluated in 7 female and 2 male patients with familial dysautonomia (FD), a disorder characterized by decreased sympathetic innervation. Prior to and after three months of midodrine treatment, each patient's response to postural change was assessed by arteriosonde readings of blood pressure and heart rate, corrected QT-interval measurements, Doppler evaluation of renal blood flow and circulating atrial natriuretic peptide (ANP) levels. The initial midodrine dose (2.5 mg three times daily) was raised until subjective symptoms improved. Doses were reduced if patients felt jittery or developed erect hypertension (systolic > 180 mmHg or diastolic > 110 mmHg). Midodrine, at an average dose of 0.25 mg/kg per day, improved subjective symptoms in all patients. With treatment, magnitude of blood pressure responses was variable. Although mean erect blood pressure did not increase significantly for the aggregate, it did increase in six of nine patients. In addition, the QTc interval normalized and erect renal perfusion improved. Changes in supine mean blood pressure and supine circulating ANP correlated directly. We judge midodrine to be useful in management of orthostatic hypotension in patients with familial dysautonomia.

Topics: Adolescent; Adrenergic alpha-Agonists; Adult; Atrial Natriuretic Factor; Blood Pressure; Dysautonomia, Familial; Female; Heart Rate; Humans; Hypotension, Orthostatic; Male; Midodrine; Renal Artery; Ultrasonography, Doppler

Circulating atrial natriuretic peptide (ANP) was assayed before and after postural change and exercise in 54 patients with familial dysautonomia (FD) and 20 controls. ANP levels were compared with blood pressure, heart rate, plasma catecholamines and parameters of renal function. Compared with controls supine FD subjects had elevated blood pressures, heart rates and ANP levels (39 +/- 4 pg/ml vs. 23 +/- 3 pg/ml, p < 0.01). With the erect posture and exercise in FD subjects, blood pressure fell below control values, with ANP lowered. In FD subjects, blood pressure was correlated with ANP levels when supine and when erect and with heart rate post exercise. In controls, ANP levels did not correlate with other parameters. In FD patients on metoclopramide, supine and erect blood pressure and ANP levels were higher. FD subjects treated with fludrocortisone, had elevated supine and erect noradrenaline (p < 0.05 and p = 0.06); and those on diazepam had lower erect and post exercise noradrenaline (p < 0.05), but ANP levels were similar. In conclusion, sympathetic denervation may increase FD patients' responsiveness to other regulators of cardiovascular integrity, such as ANP. In addition, circulating ANP and catecholamines in FD subjects appear to be influenced by commonly used medications, such as metoclopramide.

Topics: Adolescent; Adult; Atrial Natriuretic Factor; Blood Pressure; Catecholamines; Child; Diazepam; Dysautonomia, Familial; Female; Fludrocortisone; Heart Rate; Humans; Hypotension, Orthostatic; Male; Metoclopramide; Middle Aged; Posture

1. To test the hypothesis that in apparently healthy elderly subjects with orthostatic hypotension there is afferent baroreflex dysfunction, cardiovascular and neurohumoral responses were measured after separate stimuli which activated baroreceptor (head-up tilt) and non-baroreceptor (cold stress, isometric exercise) afferent pathways. 2. In 15 healthy elderly control subjects blood pressure did not change with 60 degrees head-up tilting and there was a moderate increase in heart rate, whereas in 13 subjects with age-related orthostatic hypotension head-up tilting was associated with a marked fall in blood pressure but a similar heart rate response to that in the elderly control group. In contrast, both groups of subjects had similar blood pressure and heart rate responses to cold stress and sustained isometric exercise. 3. Nine subjects with autonomic neuropathy also showed a marked hypotensive response to head-up tilt, but produced no pressor response to cold stress or isometric exercise. 4. The plasma concentrations of noradrenaline, adrenaline and neuropeptide-Y-like immunoreactivity rose and that of atrial natriuretic peptide fell after head-up tilt in the study population as a whole. There were no significant differences between groups despite the much greater blood pressure drops in the subjects with autonomic neuropathy and in those with age-associated orthostatic hypotension. 5. The aorto-iliac pulse wave velocity index was significantly higher in subjects with age-associated orthostatic hypotension compared with that in control subjects. 6. The pattern of responses to the separate stresses observed in the group with age-associated orthostatic hypotension is characteristic and different from that in the elderly control subjects and the subjects with autonomic neuropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Afferent Pathways; Aged; Aged, 80 and over; Aging; Atrial Natriuretic Factor; Autonomic Nervous System Diseases; Blood Pressure; Cold Temperature; Epinephrine; Exercise; Female; Heart Rate; Humans; Hypotension, Orthostatic; Male; Middle Aged; Neuropeptide Y; Norepinephrine; Posture; Pressoreceptors

Hyperbaria-induced diuresis is accompanied by decreased basal and stimulated release of arginine vasopressin (AVP) and decreased blood volume possibly contributing to the reported orthostatic intolerance. Since hyperosmolality is not a consistent finding, the explanation of blood volume reduction at hyperbaria must involve an osmotic component to the diuresis. Investigations of a possible involvement of atrial natriuretic peptide (ANP) to the hyperbaric diuresis have revealed mixed results.. Urinary excretion of electrolytes, AVP, and aidosterone were measured in four male subjects studied at 1 atmosphere absolute (ATA) and at 46 and 37 ATA (0.5 atmospheres pressure O2: 5% N2: remainder He) during a 35-d saturation dive. Also, the supine and 90 degrees tilt-stimulated plasma levels of AVP, plasma renin activity (PRA), and aldosterone, and the suppressed responses of ANP and the cardiovascular responses to tilt were determined at these pressures.. Tilt-stimulated levels of PRA were increased two- to threefold and the AVP response was eliminated throughout hyperbaria, except in two episodes of tilt-induced syncope where AVP was elevated 10- to 20-fold. This pattern supports most previous reports. Contrary to some reports, both supine and tilt-suppressed levels of ANP were reduced by about 50% at all three tilt experiments conducted at hyperbaria compared to predive control values.. These results suggest an altered ANP response at pressures of 37 ATA or greater, which is consistent with an appropriate ANP response to blood volume reduction and further suggest that the hyperbaric diuresis is not dependent on increased ANP.

Topics: Adult; Aldosterone; Arginine Vasopressin; Atrial Natriuretic Factor; Blood Pressure; Cardiovascular Physiological Phenomena; Cardiovascular System; Diuresis; Diving; Endocrine System; Humans; Hyperbaric Oxygenation; Hypotension, Orthostatic; Male; Prospective Studies; Renin; Risk Factors; Tilt-Table Test; Time Factors

Greater change of postural blood pressure (BP) is often seen in elderly hypertensives and is recognized as a risk factor for cognitive decline and poorer cerebrovascular outcome, but its clinical significance still remains to be clarified. We performed a head-up tilting test, ambulatory BP monitoring, and brain MRI in 59 hypertensives and 27 normotensive subjects. We measured plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels at rest to assess cardiac burden. The 59 hypertensive patients were classified into 3 groups: an orthostatic hypertension (OHT) group with orthostatic increase in systolic BP (SBP) > or = 10 mmHg (n=16); an orthostatic hypotension (OHYPO) group with orthostatic SBP decrease < or = -10 mmHg (n=18); and an orthostatic normotension (ONT) group with neither of these two patterns (n=25). A group of 27 normotensive subjects (NT) was also included as a control. Plasma BNP (72 +/- 92 vs. 29 +/- 24 pg/ml, p < 0.05) and BNP/ANP ratio (4.6 +/- 3.3 vs. 2.4 +/- 1.5, p < 0.05) were significantly higher in the OHYPO than in the NT group. The BNP/ANP ratio was also higher in the OHT than in the NT group (5.1 +/- 3.9 vs. 2.4 +/- 1.5, p < 0.01). The number of silent cerebral infarct (SCI), prevalence of SCI and number of multiple SCIs was the highest in the OHT group, followed in order by the OHYPO, ONT and NT groups. Blood pressure and left ventricular mass index were not significantly different among the 3 hypertensive groups. In conclusion, hypertensive patients with greater change of postural BP (OHT and OHYPO) were shown to have increased risk of advanced silent brain lesions and greater cardiac burden.

Topics: Aged; Aged, 80 and over; Atrial Natriuretic Factor; Blood Pressure; Cerebral Infarction; Female; Humans; Hypertension; Hypertrophy, Left Ventricular; Hypotension, Orthostatic; Magnetic Resonance Imaging; Male; Middle Aged; Natriuretic Peptide, Brain; Stroke Volume; Ventricular Dysfunction, Left

At the time of cardiac transplantation all nerves from the donor ventricles are cut. These nerves may regrow, but there is no method of measuring any regrowth. Arginine vasopressin (AVP) release was studied during hypotension induced by head-up tilt and lower body negative pressure (LBNP) in transplant recipients and in normal controls. Subjects were tilted to 60 degrees for up to 60 min or until symptomatic. Lower body negative pressure (40 mmHg) was applied for 10 min after 30 min rest. Seven of 17 transplant recipients and 11 of 12 controls became symptomatic during tilt testing, and 9 of 12 controls and 9 of 17 transplant recipients became symptomatic after 10 min of LBNP. Symptoms during tilt did not predict symptoms during LBNP. Resting AVP levels were similar but osmolality was greater in transplant recipients. Resting haematocrit was reduced, and atrial natriuretic peptide increased in transplant recipients, suggesting increased plasma volume. In symptomatic subjects, changes in humoral concentrations were similar when compared between transplant recipients and normals, except that the rise in AVP at the time of symptoms was reduced in transplant recipients, with a comparable drop in blood pressure consistent with persistent cardiac afferent denervation in a subset of transplant recipients.

Topics: Adult; Aged; Aldosterone; Arginine Vasopressin; Atrial Natriuretic Factor; Case-Control Studies; Female; Heart Transplantation; Humans; Hypotension, Orthostatic; Lower Body Negative Pressure; Male; Middle Aged; Renin; Statistics, Nonparametric; Syncope, Vasovagal; Tilt-Table Test

To determine whether exercise and Lower Body Negative Pressure (LBNP) during 28 days of -6 degrees head-down tilt (HDT) would modify orthostatic tolerance and blood volume regulating hormones, twelve healthy men were assigned to either a no- countermeasure (No-CM, n=6), or a countermeasure (CM, n=6) group. LBNP sessions consisted of 15 minutes exposure to -30 mm Hg, on days 16, 18, 20 and 22-28 of HDT. Muscular exercise began on day 8 and consisted of combined graded dynamic and isometric resistance bilateral leg exercise on a specially designed supine ergometer, in two sessions of 15-20 min. each, every day, 6 days per week. A tilt test was performed before and at the end of HDT. Changes in resting plasma volume from control day (D-5) to HDT day 24 were -11.2% for No-CM and -2.2% for CM. After HDT three among the 6 subjects of the No-CM group presented presyncopal or syncopal symptoms, no tilt test was interrupted in CM group. Atrial Natriuretic Peptide (ANP) decreased at day 7 for the two groups and remained low during all the HDT period for No-CM group only. Plasma Renin Activity and Aldosterone increased at day 7 and remained elevated for the two groups. Norepinephrine and epinephrine were unchanged. Elevated diuresis and natriuresis were evident during the first day of HDT. However, renal excretory patterns were different between the two groups: indeed, a decrease of Na+, ANP and cGMP was observed only in No-CM at Day 13 during HDT. Our data showed that the subjects of the No-CM group experienced a greater increase in heart rate and a decrease in systolic blood pressure during tilt tests after HDT; nevertheless, after HDT, blood pressure was better maintained in CM group during the tilt test. The plasma volume decrease measured at the end of HDT was significantly lower in CM group, in contrast, these countermeasures were ineffective in preventing at least certain changes in blood volume regulating hormones.

Topics: Adult; Aldosterone; Atrial Natriuretic Factor; Bed Rest; Blood Proteins; Catecholamines; Creatinine; Epinephrine; Exercise Therapy; Head-Down Tilt; Hemodynamics; Humans; Hypotension, Orthostatic; Lower Body Negative Pressure; Male; Norepinephrine; Plasma Volume; Renin; Sodium; Tilt-Table Test; Weightlessness Countermeasures

A possible relationship between endurance exercise training, susceptibility to motion sickness, and orthostatic tolerance was investigated. Male subjects underwent acceleration tolerance tests, lower body negative pressure, and Coriolis tests. During the experimental protocol, hemodynamic parameters were measured including heart rate, stroke volume, blood pressure, and cardiac output, and blood was drawn and analyzed for various hormones. Specific results are presented and discussed.

Topics: Acceleration; Adult; Aerospace Medicine; Atrial Natriuretic Factor; Disease Susceptibility; Endothelin-1; Hemodynamics; Humans; Hypotension, Orthostatic; Lower Body Negative Pressure; Male; Motion Sickness; Physical Endurance; Physical Fitness; Renin; Rotation

To study the association between postural hypotension and (i) electrolyte levels and (ii) neurohumoral factors in elderly hypertensive patients using diuretics.. Cross-sectional study of patients and controls.. The subjects were gathered from senior citizen clubs or they were referred to the study by general practitioners. The subjects were examined on a geriatric ward in Turku City Hospital.. Seven subjects with postural hypotension and 13 controls.. Plasma electrolyte levels and neurohumoral response to head-up tilt.. There were significantly more hypokalaemic subjects in the postural hypotension group (5/7) than in the control group (1/13) (P < 0.01). The plasma potassium level was negatively correlated to plasma aldosterone (r = -0.57; P < 0.01) and renin activity (r = -0.69; P < 0.001). Subjects with postural hypotension had higher levels of noradrenaline, both supine (P < 0.05) and during tilt (P < 0.05). There were no significant differences in supine or tilt levels of plasma adrenaline, vasopressin, atrial natriuretic peptide, aldosterone and renin activity between the groups.. The results suggest that potassium depletion is associated with postural hypotension in elderly hypertensive patients using diuretics. However, it is unclear whether there is a causative link between potassium depletion and postural hypotension or whether they are both caused by some other factor, e.g. volume contraction.

Topics: Aged; Aged, 80 and over; Aldosterone; Atrial Natriuretic Factor; Case-Control Studies; Cross-Sectional Studies; Diuretics; Electrolytes; Epinephrine; Female; Humans; Hypertension; Hypotension, Orthostatic; Male; Neurotransmitter Agents; Potassium; Renin; Tilt-Table Test; Vasopressins

Hyponatremia in patients with small cell lung cancer (SCLC) is a common clinical problem usually attributed to tumor secretion of arginine vasopressin (AVP). It recently was shown that some SCLC cell lines produce atrial natriuretic peptide (ANP). The purpose of this investigation was to determine the frequency and clinical consequences of secretion of ANP by SCLC and the relative contribution of ANP and AVP to the hyponatremia associated with this disease.. Levels of ANP and AVP were measured in 23 SCLC cell lines and 23 other human tumor cell lines. Also, ANP and AVP levels were determined in plasma samples from 69 patients with active small cell carcinomas.. Of the 23 SCLC lines, 16 (70%) had elevated ANP levels. Only two (8.7%) had elevated AVP levels, and these two also had elevated ANP levels. One of the ANP-producing cell lines was derived from a hyponatremic patient with no other apparent explanation for a low sodium level. However, the four cell lines with the highest levels of ANP were derived from patients who were not hyponatremic. Two other human tumor lines also produced ANP. Of the 69 patients with SCLC, 21 (30.4%) had elevated ANP levels, whereas 4 (6%) had elevated AVP levels. Fifteen of these patients were hyponatremic during their clinical course (21.7%). Of the eight patients who were hyponatremic when samples were collected, two had elevated ANP levels, and only one had elevated AVP levels. Six patients (8.7%) had symptoms of postural hypotension, possibly attributable in some cases of tumor secretion of ANP.. The majority of SCLC lines produce ANP, and a minority produce AVP. Secretion of ANP may result in hyponatremia and/or postural hypotension. However, secretion of either or both of these peptides does not account for all cases of hyponatremia in patients with SCLC and does not necessarily cause clinical manifestations.

Topics: Adenocarcinoma; Arginine Vasopressin; Atrial Natriuretic Factor; Carcinoma, Non-Small-Cell Lung; Carcinoma, Small Cell; Female; Humans; Hyponatremia; Hypotension, Orthostatic; Lung Neoplasms; Male; Sodium; Tumor Cells, Cultured

Plasma levels of atrial natriuretic peptide (ANP) increase with age. To test the hypothesis that the cardiovascular response to ANP is age dependent and to examine the role of the increased levels of ANP in the hypotensive response to orthostatic challenge, we compared the hemodynamic response of young and elderly subjects to ANP infusion and orthostatic challenge.. Blood pressure, heart rate, forearm cutaneous resistance, plasma ANP, and plasma norepinephrine were measured in the supine position and following upright tilt before and after a 60-minute infusion of atrial natriuretic peptide (0.05 microgram/kg/min) in 7 young (27 +/- 4 years) and 5 elderly (74 +/- 4 years) normotensive, healthy subjects.. Prior to ANP infusion, the response to upright tilt was similar in both groups. Infusion of ANP produced similar steady state plasma levels of ANP in both groups (young: 435 +/- 49 pg/ml; elderly: 429 +/- 32 pg/ml). Supine systolic blood pressure decreased by 4 +/- 2 mmHg in the young subjects and by 18 +/- 8 mmHg in the elderly subjects after infusion (p < .08). In contrast, changes in supine heart rate, forearm cutaneous resistance, and plasma norepinephrine were similar in both groups (delta heart rate: young +5 +/- 3 beats/min, elderly +4 +/- 2 beats/min; delta forearm cutaneous resistance: young -38 +/- 9%, elderly -40 +/- 6%; delta norepinephrine: young +55 +/- 11%, elderly: +43 +/- 13%). ANP infusion abolished the vasoconstrictor response normally associated with orthostatic challenge in both groups, despite a significant release of catecholemines and an enhanced heart rate response. This resulted in significant systolic blood pressure reduction in both young (-7 +/- 2 mmHg, p < .05) and elderly subjects (-16 +/- 4 mmHg, p < .05). The drop in systolic blood pressure in response to upright tilt and ANP infusion was four times larger in the elderly subjects (change from pre-ANP level: young -8 +/- 3 mmHg, elderly -32 +/- 5 mmHg, p < .005).

Topics: Adult; Aged; Aging; Atrial Natriuretic Factor; Blood Pressure; Heart Rate; Humans; Hypotension, Orthostatic; Norepinephrine; Skin; Vascular Resistance

To determine whether inappropriately secreted vasodilatory peptides have a role in the pathogenesis of orthostatic (postural) hypotension, a recognised paraneoplastic effect of bronchial malignancies usually attributed to immune mediated destruction of autonomic ganglia.. Serum concentrations of three vasodilatory peptides, atrial natriuretic peptide (ANP), vasoactive intestinal polypeptide (VIP) and calcitonin gene related peptide (CGRP), were measured in 111 patients with bronchial carcinoma and 35 controls prospectively screened for orthostatic hypotension (> 20 mmHg drop in systolic blood pressure on repeated occasions on standing from the supine position) and in whom other causes of this condition were excluded.. Twenty two (20%) patients with carcinoma and two (6%) controls had orthostatic hypotension according to the criteria used. Serum concentrations of ANP, VIP and CGRP were elevated above normal in, respectively, 25 (23%), 10 (9%) and eight (7%) patients with carcinoma and in six (18%), zero and three (9%) controls. There was no correlation between orthostatic hypotension and concentrations of any of the vasodilatory peptides.. Elevated serum concentrations of ANP and CGRP were no more frequent in subjects with bronchial carcinoma than in controls and could not be attributed to the tumour, although there was a possible association for VIP. Orthostatic hypotension was more common in patients with carcinoma, but there was no evidence that the peptides measured played a role in its pathogenesis.

Topics: Aged; Atrial Natriuretic Factor; Calcitonin Gene-Related Peptide; Case-Control Studies; Humans; Hypotension, Orthostatic; Lung Neoplasms; Middle Aged; Paraneoplastic Syndromes; Prospective Studies; Vasoactive Intestinal Peptide

Plasma atrial natriuretic factor (ANF) concentrations are increased in subjects with insulin-dependent diabetes mellitus (IDDM). A potential contribution of ANF to the maintenance of abnormalities in renal hemodynamic function has been considered but not proven in human diabetic subjects. The aim of these experiments was to determine the response of renal blood flow (RBF), glomerular filtration rate (GFR), filtration fraction (FF), and urinary sodium excretion (UNaV) to a reduction of plasma ANF concentrations induced by application of nonhypotensive lower body negative pressure (LBNP) in a group of subjects with early, uncomplicated, well-controlled IDDM compared with control subjects. Baseline supine measurements before LBNP revealed the diabetic subjects to have a significantly higher plasma ANF (31 +/- 2 vs. 24 +/- 2 pg/ml, P = 0.05). GFR tended to be higher (118 +/- 11 vs. 104 +/- 9 ml/min) and UNaV tended to be depressed (188 +/- 25 vs. 240 +/- 25 mumol/min) despite equal sodium intake, but not significantly so. In addition IDDM subjects exhibited significantly lower baseline plasma norepinephrine (PNE) concentrations (0.91 +/- 0.20 vs. 1.60 +/- 0.2 nmol/l, P = 0.03). Forearm vascular resistance (FVR) was not significantly different between the two groups (29 +/- 5 vs. 33 +/- 5 units). LBNP induced comparable decreases in ANF and central venous pressure (CVP) in both groups. The anticipated renal response to ANF reduction (declines in GFR, FF, and UNaV) occurred only in the normal control group. The percent decline in GFR (11% vs. 34.5%, P = 0.01) was markedly attenuated in IDDM subjects. The expected reflexive increase in PNE and FVR also did not occur in IDDM subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Aldosterone; Atrial Natriuretic Factor; Blood Pressure; Cyclic GMP; Diabetes Mellitus, Type 1; Diastole; Forearm; Glomerular Filtration Rate; Heart Rate; Humans; Hypotension, Orthostatic; Male; Muscles; Norepinephrine; Reference Values; Renal Circulation; Renin; Sodium; Supine Position; Systole; Time Factors; Vascular Resistance

The purpose of this investigation was to test the hypothesis that endurance exercise trained (ET) subjects would demonstrate a greater reduction in orthostatic tolerance as compared to untrained (UT) subjects following prior exposure to -6 degrees head-down tilt (HDT) because vasoactive hormone and enzyme responses to head-up tilt (HUT) would be decreased following HDT so as to predispose ET subjects to orthostatic intolerance. Six ET subjects (VO2peak = 4.52 +/- 0.20 L/min) were matched for age and height with six UT subjects (VO2peak = 3.26 +/- 0.22 L/min; p < 0.01). After 30 min of supine rest, subjects were exposed to 30 min of head-up tilt (HUT) at 70 degrees, then on a separate occasion, 4 h of HDT (-6 degrees) followed by 30 min of HUT. The HUT involved passive standing for 30 min or until subjects became presyncopal. Blood sampled from the antecubital vein at min 1, 15, and 30, or at presyncope was analyzed for atrial natriuretic peptide (ANP), aldosterone (PA), arginine vasopressin (AVP), plasma renin activity (PRA), and norepinephrine (NE), while BP and HR were continuously monitored. All subjects tolerating 30 min of HUT, after either condition, had significantly increased (p < 0.05) levels of PRA at the 30th min. Following 4 h of HDT, five of six UT subjects and only one of six ET subjects endured 30 min of HUT. The most marked difference during HUT after prior exposure to HDT was a significant increase in AVP (p < 0.05) at the onset of HUT observed only for the UT subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Analysis of Variance; Atrial Natriuretic Factor; Blood Volume; Exercise Tolerance; Hormones; Humans; Hypotension, Orthostatic; Lower Body Negative Pressure; Physical Fitness; Posture; Syncope

1. Overnight recumbent and upright plasma atrial natriuretic peptide (ANP) levels were markedly elevated (P less than 0.001) in patients with orthostatic hypotension (OH). 2. Overnight urinary clearance of ANP was significantly lower (P less than 0.01) in patients with OH, and was inversely correlated with plasma ANP levels (r = -0.94, P less than 0.01). The same negative correlation (r = -0.87, P less than 0.01) was seen in normal subjects. 3. Reduced urinary clearance of ANP may be associated with reduced filtered load and increased binding of ANP to the neutral endopeptidase 24.11 receptor binding sites in the proximal renal tubule. 4. ANP may be involved in the pathophysiology of orthostatic hypotension.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aldosterone; Atrial Natriuretic Factor; Blood Pressure; Humans; Hypotension, Orthostatic; Male; Middle Aged; Posture; Renin

The volume regulating hormones were studied during a 4-week head-down tilt (CNES HDT) in five subjects with and without (controls) lower body negative pressure (LBNP). LBNP was applied 3 times a day for 3 weeks, 4 times a day for 4 d, and 6 times a day for 3 d the last week. In both groups we observed a significant decrease in body weight (3% in controls, 0.8% in LBNP), a significant increase in plasma renin activity and aldosterone (with an amplification of their rhythms), and a significant decrease in norepinephrine with no difference between the two groups. The only major hormonal difference was observed for atrial natriuretic factor (ANF), which decreased significantly in the control group and increased in the LBNP group. These results are compared with the improvement in orthostatic tolerance (OT) after HDT in the LBNP group in the same protocol (17). We conclude that many factors could be involved in the improvement of OT. The results suggest that better conservation of plasma volume in the LBNP group might have prevented a decrease in ANF. Whether ANF plays a role in the regulation of baroreceptor reflex with an improvement in OT is currently unknown.

Topics: Aldosterone; Atrial Natriuretic Factor; Blood Volume; Body Fluids; Body Weight; Catecholamines; Exercise; Humans; Hypotension, Orthostatic; Lower Body Negative Pressure; Posture; Pressoreceptors; Renin; Sodium; Space Flight

Topics: Adaptation, Physiological; Atrial Natriuretic Factor; Bed Rest; Head; Humans; Hypotension, Orthostatic; Lower Body Negative Pressure; Posture; Weightlessness

To investigate whether excessive circulating levels of atrial natriuretic factor (ANF) are responsible for orthostatic hypotension and nocturnal polyuria in patients with autonomic failure, we determined the circadian variation in the plasma concentration of ANF as well as the response of this peptide to changes in posture and extracellular fluid volume in patients with autonomic failure. We found that the plasma concentration of ANF was significantly lower in patients with autonomic failure than in controls. Patients with autonomic failure had a significantly higher urinary sodium excretion during the night (8 PM to 8 AM) than during the day (8 AM to 8 PM), and the plasma concentration of ANF significantly decreased during the night in these patients, indicating that high circulating levels of ANF were not the cause of the nocturnal natriuresis. Furthermore, circulating levels of ANF responded appropriately to reductions in right atrial pressure induced by head-up tilt and extracellular fluid volume changes induced by mineralocorticoid administration. These results indicate that exaggerated circulating levels of ANF are not responsible for the orthostatic hypotension or nocturnal natriuresis in patients with autonomic failure, and that appropriate regulation of ANF occurs in patients with autonomic failure.

Topics: Adult; Aged; Atrial Natriuretic Factor; Autonomic Nervous System Diseases; Blood Pressure; Circadian Rhythm; Extracellular Space; Female; Heart Rate; Humans; Hypotension, Orthostatic; Male; Middle Aged; Posture

A patient with idiopathic orthostatic hypotension exhibited low activity of norepinephrine and renin in plasma which failed to respond to standing. Levels of atrial natriuretic factor were inappropriately elevated and failed to fall on standing. The possible role of the atrial natriuretic factor in idiopathic orthostatic hypotension is discussed.

Topics: Aged; Atrial Natriuretic Factor; Humans; Hypotension, Orthostatic; Male; Norepinephrine; Renin

Topics: Atrial Natriuretic Factor; Dopamine; Humans; Hypotension, Orthostatic

Atrial natriuretic factor (ANF) levels were ten times normal in hemodialysis patients before dialysis. ANF was not cleared by the dialyzer membrane but plasma levels decreased 47% by the end of dialysis. Patients undergoing peritoneal dialysis had plasma ANF levels four times normal and had detectable ANF in their dialysate. Hemodialysis patients with a marked fall in BP after dialysis had higher ANF levels (P less than 0.05) and lower norepinephrine (NE) levels (P less than 0.05) associated with a failure to increase NE in response to dialysis. Elevated ANF levels are associated with postdialysis hypotension in hemodialysis patients.

Topics: Adult; Aged; Atrial Natriuretic Factor; Female; Humans; Hypotension, Orthostatic; Kidney Failure, Chronic; Male; Metanephrine; Middle Aged; Norepinephrine; Normetanephrine; Peritoneal Dialysis; Renal Dialysis

We studied the influence of atrial natriuretic factor (ANF) infusion on the reflex increase in forearm vascular resistance in normotensive subjects. Reflex vasoconstriction was induced by cardiopulmonary receptor unloading [lower body negative pressure (LBNP), -20 mmHg for 15 min] or by carotid baroreceptor deactivation (+60 mmHg increase in external neck pressure by a pneumatic neck-chamber). Atrial natriuretic factor induced a significant increase in the reflex forearm vasoconstriction to LBNP, but did not modify systemic and regional reflex haemodynamic responses to carotid baroreceptor deactivation. These results suggest that ANF has important interactions with the neural control of peripheral circulation. In addition, the study shows that the peptide causes a selective potentiation of the reflex vasoconstrictor response evoked by cardiopulmonary receptor unloading.

Topics: Adult; Atrial Natriuretic Factor; Female; Forearm; Humans; Hypotension, Orthostatic; Male; Pressoreceptors; Reflex; Vascular Resistance; Vasoconstriction