Plasma vasopressin and renin activity in women exposed to bed rest and +Gz acceleration

1976 ◽  
Vol 40 (6) ◽  
pp. 911-914 ◽  
Author(s):  
L. C. Keil ◽  
S. Ellis

To study the effect of prolonged recumbency on plasma vasopressin and renin activity, eight women (23–34 yr) were subjected to 17 days of absolute bed rest. The +3 Gz tolerance of the subjects was tested before and after 14 days of bed rest. From day 2 and through day 17 of bed rest, plasma arginine vasopressin (AVP) levels were reduced 33%. Plasma renin activity (PRA) increased 91% (P less than 0.05) above ambulatory control values from days 10 through 15 of bed rest. When compared to precentrifuge values, exposure to +3 Gz prior to bed rest provoked a 20-fold rise (P less than 0.05) in mean plasma AVP but resulted in only a slight increase in PRA. After bed rest, acceleration increased plasma AVP 7-fold (P less than 0.02); however, the magnitude of this increase was less than the post +3Gz value obtained prior to bed rest. After bed rest, no significant rise was noted in PRA following +3 Gz. This study demonstrates that prolonged bed rest leads to a significant rise in the PRA of female subjects, while exposure to +Gz acceleration provokes a marked rise in plasma AVP.

1993 ◽  
Vol 85 (4) ◽  
pp. 465-470 ◽  
Author(s):  
M. Sutters ◽  
D. J. S. Carmichael ◽  
S. L. Lightman ◽  
W. S. Peart

1. A diuresis occurs within the first 36 h of salt restriction. A decline in plasma arginine vasopressin concentration may contribute to both the diuresis and antinatriuresis. 2. We have studied six normal human subjects during 36 h of dietary sodium restriction. In one study subjects received an intravenous infusion of D-glucose, and in the other an infusion of arginine vasopressin (6 fmol min−1 kg−1). 3. In the D-glucose phase plasma arginine vasopressin concentration fell (1.77 +034 to 1.02 +0.13 pg/ml), urine flow increased (67.9 +113 to 89.8 + 17.1 ml/h), haemoconcentration occurred (packed cell volume 40.8 +0.3 to 42.8 +03%, protein concentration 71.6 +03 to 74.5 + 0.6 g/l), plasma sodium concentration fell (140 +0.2 to 138 +0.2 mmol/l) and plasma renin activity increased (1600+153 to 3700 + 356 pg of angiotensin I h−1 ml−1). 4. In the arginine vasopressin phase plasma arginine vasopressin concentration remained constant (13 + 0.13 to 134 +0.11 pg/ml), the diuresis was reversed (65.7 +9.9 to 52.1 +8.9 ml/h), plasma sodium concentration fell further (139.8 +0.4 to 136.1 +0.4 mmol/l), the rise in plasma renin activity was reduced (arginine vasopressin 2552 + 292; D-glucose, 3700 + 356 pg of angiotensin I h−1 ml−1) and creatinine clearance was lower in the last 12 h of salt restriction (arginine vasopressin, 96.1 +6.9; D-glucose 116.5 + 6.8 ml/min). Renal sodium excretion was unaffected by arginine vasopressin infusion. 5. We conclude that the fall in plasma arginine vasopressin concentration during dietary salt restriction, whilst not affecting renal sodium excretion, may be important in the regulation of plasma sodium concentration, plasma renin activity and glomerular filtration.


1982 ◽  
Vol 63 (2) ◽  
pp. 121-125 ◽  
Author(s):  
S. Swart ◽  
R. F. Bing ◽  
J. D. Swales ◽  
H. Thurston

1. Plasma renin activity, body weight and blood pressure were measured before and after 7 days' treatment with bendrofluazide in ten hypertensive subjects. They were then treated with bendrofluazide alone (5 mg daily) for a minimum of 3 years. The diuretic was then discontinued and the measurements were repeated before and again after 7 days with bendrofluazide. The results were compared with those obtained before chronic treatment with the diuretic. 2. Chronic diuretic treatment was associated with a persistent and progressive rise in plasma renin activity, that fell promptly to pretreatment levels when diuretics were discontinued. This was associated with significant weight gain but no immediate significant rise in blood pressure. 3. When acutely challenged with bendrofluazide the patients showed a greater increase in plasma renin activity on the second occasion than on the first. Three out of five patients with an initially subnormal response had normal responses after chronic diuretic treatment. 4. Chronic diuretic treatment increased the responsiveness of the juxtaglomerular apparatus in some hypertensive patients. 5. Classification of hypertensive patients into renin subgroups may be influenced by previous therapy, even when that therapy has been discontinued for 4 weeks. In particular ‘low renin hypertension’ may be masked by recent use of diuretics, as shown by three of the five patients in this subgroup in the present study.


1984 ◽  
Vol 247 (6) ◽  
pp. R968-R971 ◽  
Author(s):  
G. Geelen ◽  
L. C. Keil ◽  
S. E. Kravik ◽  
C. E. Wade ◽  
T. N. Thrasher ◽  
...  

To study the effects of nonosmotic and nonvolumetric factors that may influence secretion of vasopressin, serum Na+, K+, and osmolality (Osm), hemoglobin, hematocrit, plasma arginine vasopressin (AVP), aldosterone (PA), and renin activity (PRA) were measured in five men and three women (26–50 yr, 73 +/- 4 kg) before and after 24 h of mild dehydration (food but no fluid) and seven times during the 1st h after rehydration with 10 ml/kg of tap water (17.5 +/- 0.5 degrees C) consumed in 105 s (range 35-240 s). Dehydration increased mean serum Na+ 3.7 +/- 0.7 meq/l (P less than 0.05), osmolality 9.1 +/- 1.1 mosmol/kg (P less than 0.05), and AVP from a hydrated level of 1.7 +/- 0.2 to 3.3 +/- 0.5 pg/ml (delta = 1.6 pg/ml, P less than 0.05). After rehydration AVP fell to 2.4 +/- 0.3 pg/ml (P less than 0.05) within 3 min and reached the water-replete level of 1.8 +/- 0.3 pg/ml 9 min after drinking started. Serum Na+ and Osm did not change until 30–60 min after drinking. No significant changes occurred in PRA, hemogloblin, hematocrit, or calculated delta in plasma volume, but PA increased from 11.1 +/- 1.5 ng/dl after dehydration to 15.6 +/- 2.6 ng/dl (P less than 0.05) between 30 and 60 min after drinking. The rapid fall in plasma AVP after rehydration took place in the absence of the expected changes in the primary regulators of plasma AVP (i.e., osmolality and plasma volume), with no change in blood pressure. The results suggest that oropharyngeal factors, alone or combined with gastric stimuli, are implicated.


1981 ◽  
Vol 61 (4) ◽  
pp. 407-415 ◽  
Author(s):  
S. Moss ◽  
D. Gordon ◽  
Mary L. Forsling ◽  
W. S. Peart ◽  
V. H. T. James ◽  
...  

1. The electrolyte and water composition of urine and ileal fluid was studied in six patients with ileostomies during dietary sodium deprivation and at the same time measurements were made of plasma renin activity, plasma aldosterone concentration, renal aldosterone excretion and plasma arginine vasopressin concentration. 2. In each subject there was a reduction in renal sodium excretion within 24 h of sodium deprivation. Significant rises in plasma renin activity, plasma aldosterone concentration and renal aldosterone excretion occurred by day 2 of sodium deprivation. 3. There was only modest conservation of sodium by the ileum during sodium deprivation, but ileal potassium concentration rose progressively. There were significant associations between ileal-fluid potassium concentration and plasma renin activity or renal aldosterone excretion. 4. Under the conditions of the experiment a diuresis was observed in each subject during dietary sodium deprivation. This did not appear to depend on changes in plasma arginine vasopressin concentration.


1976 ◽  
Vol 51 (3) ◽  
pp. 267-274 ◽  
Author(s):  
Roy Davies ◽  
J. D. H. Slater ◽  
Mary L. Forsling ◽  
Nadia Payne

1. Fourteen mildly hydropenic normal volunteers were slowly tilted at a constant rate from the horizontal to the 85° head-up position in order to study the interrelationship between plasma arginine vasopressin concentration, plasma renin activity and the change of plasma volume. 2. Nine subjects did not develop vaso-vagal symptoms and were studied for 45–60 min. Arginine vasopressin rose biphasically in all subjects: a small initial rise, which was seen at 3 min and persisted for 30 min, was followed by a striking rise between 30 and 45 min, when the fall of plasma volume had reached its maximum (17%). 3. Plasma renin activity reached a maximum at 30 min but fell by 45 min, as plasma concentration of arginine vasopressin rose. 4. Five subjects developed vaso-vagal symptoms 4–24 min after reaching 85° when the study was terminated. A striking increase of arginine vasopressin concentration was seen within 4 min of syncope, but there was no change of plasma osmolality, cortisol concentration or renin activity.


1991 ◽  
Vol 261 (1) ◽  
pp. R223-R230 ◽  
Author(s):  
M. Keller-Wood ◽  
C. E. Wood

The gonadal axis is thought to modulate adrenocorticotropic hormone (ACTH), arginine vasopressin (AVP), and plasma renin activity (PRA) responses to stimuli in several species. These experiments were designed to compare the responses to hypotension in chronically ovariectomized ewes and intact ewes. The ewes were infused with nitroprusside at rates of 5, 10, or 15 micrograms.kg-1.min-1 or infused with vehicle for 10 min. The response to 15 micrograms.kg-1.min-1 was also tested with or without treatment with 10 mg of dexamethasone 2 h before nitroprusside. Blood samples were collected before and at 5, 10, 15, 20, and 30 min after the start of the infusion for measurement of plasma ACTH, AVP, and PRA. In both groups of animals there were significant responses to hypotension. There was a significant effect of ovariectomy on ACTH, AVP, and PRA responses. ACTH and PRA responses were lower in the ovariectomized ewes; AVP responses were increased in the ovariectomized ewes. Administration of dexamethasone inhibited ACTH responses and did not inhibit PRA responses in both groups of ewes. Administration of dexamethasone did not inhibit the AVP response in the intact ewes but did reduce the response in the ovariectomized ewes.


1986 ◽  
Vol 250 (4) ◽  
pp. R633-R637
Author(s):  
J. E. Szilagyi ◽  
J. Chelly ◽  
M. F. Doursout

The influence of blockade of endogenous opioids on the release of renin due to partial renal arterial constriction was determined acutely and chronically in unilaterally nephrectomized dogs. In acute preparations changes in plasma renin activity, arterial blood pressure, and heart rate were determined after 15 min of 60% renal arterial constriction before and after administration of either a saline vehicle, the opiate antagonist naloxone (0.05 mg/kg), or morphine (2 mg/kg). Acute antagonism of endogenous opiates abolished the increase in plasma renin activity and mean arterial pressure associated with renal arterial constriction. Repeated renal arterial constrictions in saline- or morphine-treated animals did not alter the humoral or hemodynamic responses. In chronic preparations long-term naloxone infusion attenuated the development of renovascular hypertension and diminished the increase in plasma renin activity. These data suggest that endogenous opioid peptides are modulators in the control of renin release and may be important participants in the pathogenesis of hypertension.


2000 ◽  
Vol 88 (1) ◽  
pp. 300-307 ◽  
Author(s):  
Takeshi Nishiyasu ◽  
Kei Nagashima ◽  
Ethan R. Nadel ◽  
Gary W. Mack

We examined the hypothesis that activation of the muscle metaboreflex during dynamic exercise would augment influences tending to cause a rise in arginine vasopressin, plasma renin activity, and catecholamines during dynamic exercise in humans. Ten healthy adults performed 30 min of supine cycle ergometer exercise at ∼50% of peak oxygen consumption with or without moderate muscle metaboreflex activation by application of 35 mmHg lower body positive pressure (LBPP). Application of LBPP during the first 15 or last 15 min of exercise increased mean arterial blood pressure, plasma lactate concentration, and minute ventilation, indicating an activation of the muscle metaboreflex. These changes were rapidly reversed when LBPP was removed. During exercise at this intensity, LBPP augmented the release of arginine vasopressin and catecholamines but not of plasma renin activity. These results suggest that, although in humans hormonal responses are induced by moderate activation of the muscle metaboreflex during dynamic exercise, the thresholds for these responses may not be uniform among the various glands and hormones.


1979 ◽  
Vol 57 (s5) ◽  
pp. 229s-231s ◽  
Author(s):  
W. Januszewicz ◽  
M. Sznajderman ◽  
B. Wocial ◽  
T. Feltynowski ◽  
T. Klonowicz

1. Ten patients with essential hypertension and ten healthy men were submitted to mental stress consisting of Kraepelin's arithmetic test combined with noise. Concentrations of plasma and urine catecholamines and of their metabolites as well as plasma renin activity before and after the test were studied. 2. In both groups a significant increase of noradrenaline and adrenaline in blood and noradrenaline in urine was observed. The urinary excretion of dopamine fell significantly in both groups after stress. 3. After mental stress a significant increase in urinary excretion of 3-methoxy-4-hydroxyphenylglycol was observed in both groups. The excretion of vanillylmandelic acid decreased significantly only in healthy subjects. 4. The plasma renin activity rose significantly in both groups but the increase was more pronounced in healthy subjects.


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