Effects of hypoxia and atrial natriuretic peptide on aldosterone secretion in healthy subjects

1993 ◽  
Vol 75 (2) ◽  
pp. 534-539 ◽  
Author(s):  
R. G. Westendorp ◽  
A. N. Roos ◽  
M. Simons ◽  
W. Wertheim ◽  
F. H. Bosch ◽  
...  

To evaluate the inhibitory effect of hypoxia and atrial natriuretic peptide (ANP) on aldosterone secretion, 11 healthy male subjects were infused with 5 ng.kg-1 x min-1 ANP or placebo. The subjects were exposed in a stepwise fashion to incremental hypobaric hypoxia, which decreased arterial oxygen saturation to 79 +/- 2% in the placebo and 84 +/- 2% in the ANP condition (P < 0.05). In the placebo condition, the plasma ANP concentration increased from 13.8 +/- 1.0 to 19.6 +/- 2.3 pmol/l (P < 0.01) at the lowest barometric pressure. Plasma renin activity did not change, whereas the plasma aldosterone levels increased consequent to the increase of plasma adrenocorticotropic hormone (ACTH). Continuous infusion of ANP increased the plasma levels twofold (P < 0.001) and the level of guanosine 3',5'-cyclic monophosphate threefold (P < 0.001). However, the plasma aldosterone concentrations were not different in the two experimental conditions. Administration of supplementary oxygen significantly decreased ACTH to baseline values (P < 0.01) together with a decrease in aldosterone. Free water clearance (P = 0.05) but not sodium excretion (P = NS) increased during continuous ANP infusion. The data indicate that the aldosterone secretion in hypoxia is not inhibited by (patho)physiological plasma ANP levels. The inhibition of aldosterone secretion may well be explained by a direct effect of hypoxia on the adrenal cells. ACTH is a major stimulus of aldosterone secretion in hypoxia, which overrides the natriuretic effect of ANP.

1987 ◽  
Vol 72 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Lynn Chartier ◽  
Ernesto L. Schiffrin

1. Previous studies have shown that atrial natriuretic peptide (ANP) inhibits the secretion of aldosterone by isolated adrenal glomerulosa cells stimulated by angiotensin II, adrenocorticotropic hormone and potassium in vitro. We have also demonstrated that this inhibitory effect of ANP on plasma aldosterone induced by angiotensin II and adrenocorticotropic hormone can be reproduced in vivo in conscious unrestrained rats. In this study, we have investigated the effect of an intravenous infusion of ANP on plasma aldosterone in conscious unrestrained sodium-depleted rats. 2. During sodium depletion, the rise in plasma renin activity which determines an increment in the circulating concentration of angiotensin II was accompanied by a rise in aldosterone secretion as expected. ANP infused intravenously at a dose which increased the plasma concentration of the peptide three- to five-fold, produced a significant decrement in the concentration of aldosterone in plasma after an infusion period of 120 min. There was no significant effect of ANP on plasma renin activity and plasma corticosterone concentration. 3. Since the increase in plasma aldosterone levels in sodium-depleted rats is mainly dependent on the activation of the renin–angiotensin system, we conclude that ANP may modulate the effect of endogenous as well as exogenous angiotensin II on plasma aldosterone secretion.


1991 ◽  
Vol 261 (4) ◽  
pp. F706-F719 ◽  
Author(s):  
P. Q. Barrett ◽  
C. M. Isales ◽  
W. B. Bollag ◽  
R. T. McCarthy

Two populations of voltage-dependent Ca2+ channels, T-type and L-type, are present in bovine adrenal glomerulosa cells. Activation of these channels by cell depolarization with the resultant increase in Ca2+ influx may be one way in which agonists regulate aldosterone secretion. In addition, these channels may be the site of antagonist action. In the present study, we have demonstrated that atrial natriuretic peptide (ANP), an antagonist of aldosterone secretion, alters only the voltage dependence of inactivation of the T-type channel while enhancing the voltage dependence of activation of a subpopulation of L-type channels. These patch-clamp data, which demonstrated contrasting effects of ANP on the activity of T- and L-type Ca2+ channels correlated with changes induced in cytosolic calcium [( Ca2+]i). In the weakly depolarized cell, ANP (greater than 30 pM) lowered [Ca2+]i, in contrast to the strongly depolarized cell, in which ANP (greater than 10 pM) raised [Ca2+]i. Similar alterations in the level of [Ca2+]i in the stimulated cell were induced by the Ca(2+)-channel blocker nitrendipine and the L-type channel agonist, (-)BAY K 8644. With increasing concentrations of extracellular K+ (3.5-60 mM) the rate of aldosterone secretion rose nonmonotonically. ANP inhibited secretion over this broad range of K+ concentrations; however, its potency as an inhibitor of secretion was diminished in the strongly depolarized cell. These data are discussed in the context of a model that proposes a role for sustained Ca2+ influx in cell activation.


1988 ◽  
Vol 65 (5) ◽  
pp. 1929-1937 ◽  
Author(s):  
P. Bartsch ◽  
S. Shaw ◽  
M. Franciolli ◽  
M. P. Gnadinger ◽  
P. Weidmann

To test the hypothesis that elevated atrial natriuretic peptide (ANP) may be involved in altered fluid homeostasis at high altitude, we examined 25 mountaineers at an altitude of 550 m and 6, 18, and 42 h after arrival at an altitude of 4,559 m, which was climbed in 24 h starting from 3,220 m. In 14 subjects, symptoms of acute mountain sickness (AMS) were absent or mild (group A), whereas 11 subjects had severe AMS (group B). Fluid intake was similar in both groups. In group B, urine flow decreased from 61 +/- 8 (base line) to 36 +/- 3 (SE) ml/h (maximal decrease) (P less than 0.05) and sodium excretion from 7.9 +/- 0.9 to 4.6 +/- 0.7) mmol.l-1.h-1 (P less than 0.05); ANP increased from 31 +/- 4 to 87 +/- 26 pmol/l (P less than 0.001), plasma aldosterone from 191 +/- 27 to 283 +/- 55 pmol/l (P less than 0.01 compared with group A), and antidiuretic hormone (ADH) from 1.0 +/- 0.1 to 2.9 +/- 1.2 pmol/l (P = 0.08 compared with group A). These variables did not change significantly in group A, with the exception of a decrease in plasma aldosterone from 189 +/- 19 to 111 +/- 17 pmol/l (P less than 0.01). There were no measurable effects of elevated ANP on natriuresis, cortisol, or blood pressure. The reduced diuresis in AMS may be explained by increased plasma aldosterone and ADH overriding the expected renal action of ANP. The significance of elevated ANP in AMS remains to be established.(ABSTRACT TRUNCATED AT 250 WORDS)


The Lancet ◽  
1985 ◽  
Vol 325 (8437) ◽  
pp. 1101 ◽  
Author(s):  
E. Jungmann ◽  
H.J.C. Wenisch ◽  
S. Abdelhamid ◽  
C. Timm ◽  
K. Schöffling

1987 ◽  
Vol 65 (10) ◽  
pp. 2076-2080 ◽  
Author(s):  
W. M. Leung ◽  
A. G. Logan ◽  
P. J. Campbell ◽  
T. E. Debowski ◽  
S. B. Bull ◽  
...  

The response of plasma atrial natriuretic peptide (ANP) and urinary cGMP excretion to central hypervolemia induced by water immersion was assessed twice in five healthy male subjects, once while immersed in water to the neck for 3 h and again on a control day. Plasma ANP and urinary cGMP were measured by radioimmunoassay. Compared with the control day, overall change in plasma ANP on the immersion day was significant (p < 0.05). In response to water immersion, plasma ANP increased from a base-line level of 13.2 ± 3.1 (mean ± SEM) to 24.2 ± 5.5 pg/mL by 0.5 h of immersion and was sustained at that level throughout the immersion period. Plasma ANP returned to the base-line level at 1 h postimmersion. Urinary cGMP excretion increased significantly by 1 h of immersion and was sustained at that level throughout water immersion and 1 h postimmersion (p < 0.05). During water immersion urine flow, urinary sodium and potassium excretion, free water clearance, and osmolar clearance increased while plasma renin activity, serum aldosterone, and blood pressure fell; all changes were significant (p < 0.05). Creatinine clearance and hematocrit did not show any significant changes. These data suggest that an increase in plasma ANP may contribute to the natriuretic and diuretic response to central hypervolemia, and that the measurement of urinary cGMP may be a valuable marker of ANP biological responsiveness.


1992 ◽  
Vol 47 (6) ◽  
pp. B214-B219 ◽  
Author(s):  
P. Cugini ◽  
P. Lucia ◽  
L. D. Palma ◽  
M. Re ◽  
R. Canova ◽  
...  

1995 ◽  
Vol 88 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Robert I. Cargill ◽  
Allan D. Struthers ◽  
Brian J. Lipworth

1. Atrial natriuretic peptide and brain natriuretic peptide have similar vasodilator and natriuretic properties, although little information is available regarding their relative effects as antagonists of the renin—angiotensin—aldosterone system. We have therefore compared how atrial natriuretic peptide and brain natriuretic peptide affect the systemic pressor and aldosterone responses to angiotensin II in eight male subjects. 2. Each subject was studied on three separate occasions, when they received a 60-min infusion of placebo, atrial natriuretic peptide (10 pmol min−1 kg−1) or brain natriuretic peptide (10 pmolmin−1 kg−1), with a concomitant infusion of angiotensin II (6 ng min−1 kg−1) given for the final 30 min of the infusion period. The change in haemodynamic parameters and plasma aldosterone induced by angiotensin II was measured. Plasma concentrations of atrial natriuretic peptide (182 ± 23 pmol/l) and brain natriuretic peptide (193 ± 25 pmol/l) achieved at steady-state during the infusion on each study day were not significantly different. 3. Increases in mean arterial pressure in response to angiotensin II were significantly lowered by concomitant infusion of atrial natriuretic peptide (21.0 ± 1.7 mmHg) and brain natriuretic peptide (20.1 ± 1.9 mmHg) compared with placebo (29.0 ± 4.1 mmHg). There were similar effects on systolic and diastolic blood pressure. Cardiac output was decreased on each study day to the same extent by angiotensin II infusion. Total systemic vascular resistance showed a non-significant trend towards an attenuated response to angiotensin II when atrial natriuretic peptide or brain natriuretic peptide was infused concomitantly in comparison with placebo. 4. Plasma aldosterone increased by 326 ± 49 pmol/l when angiotensin II was infused with placebo. Both atrial natriuretic peptide and brain natriuretic peptide significantly blunted this response, although the increase with atrial natriuretic peptide (19 ± 35 pmol/l) was significantly lower than the increase with brain natriuretic peptide (133 ± 19 pmol/l). 5. Atrial natriuretic peptide and brain natriuretic peptide were therefore equally effective in blunting the systemic pressor response to angiotensin II. It was apparent, however, in view of similar plasma concentrations at steady state, that on a molar basis atrial natriuretic peptide was a more potent inhibitor of angiotensin II-induced aldosterone secretion than brain natriuretic peptide. These results suggest a dissociation between the haemodynamic and hormonal effects of atrial natriuretic peptide and brain natriuretic peptide in terms of antagonism of the renin—angiotensin—aldosterone system.


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