EFFECTS OF PROLONGED INFUSIONS OF POTASSIUM CHLORIDE, ADRENOCORTICOTROPHIN OR ANGIOTENSIN II UPON SERUM ALDOSTERONE CONCENTRATION AND THE CONVERSION OF CORTICOSTERONE TO ALDOSTERONE IN RATS

1979 ◽  
Vol 90 (4) ◽  
pp. 680-691 ◽  
Author(s):  
Jan Komor ◽  
Jürg Müller
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Potassium Chloride ◽  
Conversion Rate ◽  
Potassium Deficiency ◽  
The Other ◽  
Serum Aldosterone ◽  
Acth Treatment ◽  
Sodium And Potassium

ABSTRACT The temporal relation between alterations in serum aldosterone and in the conversion of labelled corticosterone to aldosterone by incubated adrenal tissue was studied in conscious rats receiving long-term infusions of KCl, ACTH or angiotensin II. When potassium-deficient rats were given KCl, a marked increase in serum aldosterone was observed only after 12 h, i.e. at a time when the conversion of corticosterone to aldosterone had become normal. After 24 h of ACTH infusion into sodiumand potassium-replete rats the serum aldosterone was markedly elevated, whereas the conversion of corticosterone to aldosterone was significantly decreased. After 48 h of continued ACTH infusion the serum aldosterone returned to normal and there was a further decrease in the conversion rate. A 24-h angiotensin II infusion into sodium- and potassium-replete rats induced significant increases in both the serum aldosterone and the conversion. After 48 h of continued angiotensin infusion the serum aldosterone returned to normal while the conversion and the blood pressure remained elevated. These results indicate that the activity of the enzymes involved in the final steps of aldosterone biosynthesis may become ratelimiting for the secretion of aldosterone during potassium deficiency and during prolonged ACTH treatment. On the other hand, the observed transiency of aldosterone stimulation by exogenous angiotensin II was not due to a suppression of the final steps of aldosterone biosynthesis and remains unexplained.

Abstract 39: Adrenal ßArrestin1 Raises Serum Aldosterone Levels And Blood Pressure, Both Significant Stroke Risk Factors, In Experimental Rats And Mice

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Anastasios Lymperopoulos ◽  
Ashley Bathgate ◽  
Norma C Salazar
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Gene Delivery ◽  
Adrenal Cortex ◽  
Stroke Risk ◽  
Fluorescent Protein ◽  
Serum Aldosterone ◽  
Increased Risk ◽  
In Vivo Gene Delivery

Introduction: It is widely accepted nowadays that elevation of serum levels of aldosterone, a mineralocorticoid hormone with toxic effects in several cardiovascular tissues, including the heart and cerebral blood vessels, can significantly raise stroke risk. The success of mineralocorticoid receptor blockers, such as eplerenone, at preventing stroke attacks attests to this. Aldosterone is normally produced and secreted by the adrenal cortex in response to angiotensin II. We recently reported that adrenal βarrestin1 (βarr1) plays a crucial role in the physiological angiotensin II-stimulated aldosterone production in the adrenal cortex, leading to marked elevation of circulating serum aldosterone levels in vivo (Lymperopoulos A. et al., Proc. Natl. Acad. Sci. USA. 2009;106:5825-5830). Hypothesis: Herein, we examined the potential impact of this adrenal βarr1-dependent aldosterone elevation on stroke risk in experimental animals in vivo. Methods: We used the βarr1 knockout (βarr1KO) mouse model, studying it alongside wild type (WT) control mice, and also adult male Sprague-Dawley rats, in which adrenal βarr1 was overexpressed in vivo via adrenal-targeted adenoviral-mediated βarr1 gene transfer. Serum aldosterone was measured by ELISA and blood pressure via telemetry. Results: Serum aldosterone at 7 days post-in vivo gene delivery was markedly elevated in adrenal βarr1-overexpressing rats (536+50 pg/ml), compared to control rats receiving the green fluorescent protein (GFP) adenoviral transgene (235+40 pg/ml, p<0.05, n=5). This translated to a significant increase in mean arterial pressure of the βarr1-overexpressing rats (155+5 mmHg) compared to control GFP-expressing rats (137+8 mmHg, p<0.05, n=5), again at 7 days post-in vivo gene delivery, which was prevented by concurrent eplerenone treatment. In contrast, βarr1KO mice had significantly lower serum aldosterone levels (270+20 pg/ml) compared to WT controls (498+35 pg/ml, p<0.05, n=5), at 4 weeks post-experimental myocardial infarction. Conclusions: Adrenal βarr1 up-regulation can dramatically increase circulating aldosterone levels and systemic blood pressure, thus conferring increased risk for stroke in experimental rodents.

scholarly journals Impact of angiotensin II-mediated stimulation of sodium transporters in the nephron assessed by computational modeling

2019 ◽  
Vol 317 (6) ◽  
pp. F1656-F1668 ◽  
Author(s):  
Aurélie Edwards ◽  
Alicia A. McDonough
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Ang Ii ◽  
Sodium Transporters ◽  
Short And Long Term ◽  
Physiological Impact ◽  
Pressure Natriuresis ◽  
Excretion Rates ◽  
Volume Output

Angiotensin II (ANG II) raises blood pressure partly by stimulating tubular Na+ reabsorption. The effects of ANG II on tubular Na+ transporters (i.e., channels, pumps, cotransporters, and exchangers) vary between short-term and long-term exposure. To better understand the physiological impact, we used a computational model of transport along the rat nephron to predict the effects of short- and long-term ANG II-induced transporter activation on Na+ and K+ reabsorption/secretion, and to compare measured and calculated excretion rates. Three days of ANG II infusion at 200 ng·kg−1·min−1 is nonpressor, yet stimulates transporter accumulation. The increase in abundance of Na+/H+ exchanger 3 (NHE3) or activated Na+-K+-2Cl− cotransporter-2 (NKCC2-P) predicted significant reductions in urinary Na+ excretion, yet there was no observed change in urine Na+. The lack of antinatriuresis, despite Na+ transporter accumulation, was supported by Li+ and creatinine clearance measurements, leading to the conclusion that 3-day nonpressor ANG II increases transporter abundance without proportional activation. Fourteen days of ANG II infusion at 400 ng·kg−1·min−1 raises blood pressure and increases Na+ transporter abundance along the distal nephron; proximal tubule and medullary loop transporters are decreased and urine Na+ and volume output are increased, evidence for pressure natriuresis. Simulations indicate that decreases in NHE3 and NKCC2-P contribute significantly to reducing Na+ reabsorption along the nephron and to pressure natriuresis. Our results also suggest that differential regulation of medullary (decrease) and cortical (increase) NKCC2-P is important to preserve K+ while minimizing Na+ retention during ANG II infusion. Lastly, our model indicates that accumulation of active Na+-Cl− cotransporter counteracts epithelial Na+ channel-induced urinary K+ loss.

scholarly journals Long-term exercise attenuates blood pressure responsiveness and modulates kidney angiotensin II signalling and urinary sodium excretion in SHR

2011 ◽  
Vol 12 (4) ◽  
pp. 394-403 ◽  
Author(s):  
Silmara Ciampone ◽  
Rafael Borges ◽  
Ize P de Lima ◽  
Flávia F Mesquita ◽  
Elizabeth C Cambiucci ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Exercise Training ◽  
Sodium Excretion ◽  
Urinary Sodium Excretion ◽  
Urinary Sodium ◽  
Receptor Expression ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto

Observations have been made regarding the effects of long-term exercise training on blood pressure, renal sodium handling and renal renin–angiotensin–aldosterone (RAS) intracellular pathways in conscious, trained Okamoto–Aoki spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKy) normotensive rats, compared with appropriate age-matched sedentary SHR and WKy. To evaluate the influence of exercise training on renal function and RAS, receptors and intracellular angiotensin II (AngII) pathway compounds were used respectively, and lithium clearance and western blot methods were utilised. The current study demonstrated that increased blood pressure in SHR was blunted and significantly reduced by long-term swim training between the ages of 6 and 16 weeks. Additionally, the investigators observed an increased fractional urinary sodium excretion in trained SHR (SHRT) rats, compared with sedentary SHR (SHRS), despite a significantly decreased creatinine clearance (CCr). Furthermore, immunoblotting analysis demonstrated a decreased expression of AT1R in the entire kidney of TSHR rats, compared with SSHR. Conversely, the expression of the AT2R, in both sedentary and trained SHR, was unchanged. The present study may indicate that, in the kidney, long-term exercise exerts a modulating effect on AngII receptor expression. In fact, the present study indicates an association of increasing natriuresis, reciprocal changes in renal AngII receptors and intracellular pathway proteins with the fall in blood pressure levels observed in TSHR rats compared with age-matched SSHR rats.

Changes in blood pressure and body sodium of rats fed sodium and potassium chloride

1961 ◽  
Vol 8 (4) ◽  
pp. 527-532 ◽  
Author(s):  
George R. Meneely ◽  
Janet Lemley-Stone ◽  
William J. Darby
Keyword(s):  
Blood Pressure ◽  
Potassium Chloride ◽  
Body Sodium ◽  
Sodium And Potassium

Effect of [Sar1, Ala8]-angiotensin II and hypophysectomy on the intestinal resistance vessels and blood pressure following furosemide-induced volume depletion

1976 ◽  
Vol 54 (3) ◽  
pp. 373-380 ◽  
Author(s):  
J. Robert McNeill ◽  
William C. Wilcox ◽  
Raoul Regnault
Keyword(s):  
Blood Pressure ◽  
Control System ◽  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Adrenal Glands ◽  
The Other ◽  
Volume Depletion ◽  
Competitive Antagonist ◽  
Vasoconstrictor Response ◽  
Resistance Vessels

Intravenous administration of furosemide (2 mg/kg) caused intestinal vasoconstriction in various groups of pentobarbital-anesthetized cats. [Sar1, Ala8]-angiotensin II, a specific competitive antagonist of angiotensin II, was infused 60 min after administration of furosemide, a time when the intestinal vasoconstrictor response to the diuretic was maximal or near maximal. In hypophysectomized animals, infusion of the antagonist abolished the intestinal vasoconstriction and caused a significant fall in arterial pressure even when the intestinal nerves and adrenal glands remained intact. In contrast, the antagonist had little effect when the pituitary gland remained intact. The results suggest that endogenous angiotensin and vasopressin are overlapping mechanisms which constrict the intestinal resistance vessels and support arterial pressure following furosemide-induced volume depletion. In the absence of one control system, the other compensates to maintain the responses.

Effect of Sodium Depletion on the Steroidogenic and Pressor Actions of Angiotensin in the Rat

1979 ◽  
Vol 56 (4) ◽  
pp. 325-333 ◽  
Author(s):  
W. B. Campbell ◽  
J. M. Schmitz ◽  
H. D. Itskovitz
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Sodium Depletion ◽  
Angiotensin I ◽  
Arterial Blood ◽  
Serum Aldosterone ◽  
Pressor Responses ◽  
Angiotensin Iii

1. To investigate the relative roles of angiotensin II (AII) and des-Asp1-angiotensin II (angiotensin III) in the control of blood pressure and aldosterone release, the effects of seven angiotensin agonists on mean arterial blood pressure and serum aldosterone concentrations were compared in normal and sodium-depleted, conscious rats. 2. In normal rats, angiotensin I, α-Asp1-angiotensin II, β-Asp1-angiotensin II, and angiotensin II-amide were equipotent in elevating mean arterial blood pressure. Angiotensin III, des-Asp1-angiotensin I, and poly-O-acetylserine-angiotensin II were 25%, 25%, and 41% as potent as angiotensin II, respectively. After sodium depletion, pressor responses to these angiotensin peptides were reduced approximately 60–80% when compared with control responses. In contrast, pressor responses to noradrenaline were not significantly affected by sodium depletion. 3. Angiotensin II, β-Asp1-angiotensin II, angiotensin II-amide, and angiotensin III were equipotent in increasing serum aldosterone concentrations in normal animals. Angiotensin I was 59% and des-Asp1-angiotensin I only 5% as potent as angiotensin II in their abilities to release aldosterone. After sodium depletion, control serum aldosterone concentrations increased as did the slope of the dose—response curve for each angiotensin peptide. Angiotensin II was the most potent steroidogenic peptide in sodium-depleted rats with angiotensin III and β-Asp1-angiotensin II being 27%, angiotensin I 7%, angiotensin II-amide 3%, and des-Asp1-angiotensin I 1% as potent as angiotensin II in releasing aldosterone. Poly-O-acetylserine-angiotensin II has less steroidogenic effect than angiotensin II or III in both normal and sodium-depleted animals. 4. Infusions of the angiotensin II antagonist, Sar1-Ile8-angiotensin II, and the angiotensin III antagonist, Ile7-angiotensin III, enhanced aldosterone release in normal rats without altering blood pressure. After sodium depletion, Sar1-Ile8-angiotensin II decreased blood pressure without affecting aldosterone release whereas Ile7-angiotensin III diminished aldosterone release without altering blood pressure. 5. These data suggest that angiotensin II, independent of its conversion into angiotensin III, is an important regulator of steroidogenesis in the rat in normal sodium states. In sodium depletion, the octapeptide retains significant steroidogenic activity; however, the contribution of angiotensin III to its steroidogenic effects is increased.

Abstract 76: Effects of Long-term Angiotensin-II Infusion on Cardiac and Renal Fibrosis are Blunted in TNFR1-deficient Mice

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Magdalena Mayr ◽  
Clemens Duerrschmid ◽  
Dorellyn B Lee ◽  
Guillermo Medrano ◽  
George E Taffet ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Systolic Blood Pressure ◽  
Renal Fibrosis ◽  
Cardiac Fibrosis ◽  
Ang Ii ◽  
Fibrotic Response ◽  
2D Echocardiography ◽  
Collagen Iii

Background: Brief systemic infusion of Angiotensin-II (Ang-II) to wild-type (WT) mice initiates the development of cardiac interstitial fibrosis. Genetic deletion of tumor necrosis factor receptor 1 (TNFR1) obviates this development and concurrently inhibits Ang-II-induced cardiac remodeling and dysfunction. We now investigated long-term effects of Ang-II on the heart, kidney, and cardiorenal function. Methods: WT and TNFR1-KO mice were infused with 1.5 ug/kg/min Ang-II for 1 and 6 weeks (no uninephrectomy or high-salt diet). Heart, kidney, and serum were isolated and evaluated by histology, cytometry, qPCR, and ELISA techniques. Cardiac function was determined by 2D-echocardiography, systolic blood pressure by tail-cuff plethysmography. Results: Brief infusion of Ang-II to WT mice did not evoke a fibrotic response in the kidney. However, after 6 weeks, WT kidneys developed minimal, but significant interstitial collagen deposition which was supported by upregulation of collagen-I, collagen-III, and alpha-smooth muscle actin gene activation. This fibrotic development was associated with the appearance of myeloid fibroblast precursors, pro-inflammatory M1 and pro-fibrotic M2 cells, and myofibroblasts. Transcriptional expression of pro-inflammatory and pro-fibrotic genes was also increased. These changes were not seen in Ang-II-infused TNFR1-KO kidneys. In WT hearts, despite the disappearance of myeloid cells, cardiac fibrosis persisted throughout the 6-week infusion. WT hearts developed clear evidence of accelerated cardiac hypertrophy and remodeling associated with impaired systolic function. Again, these changes were not seen in Ang-II-infused TNFR1-KO hearts. By contrast, both WT and TNFR1-KO mice responded identically with similar elevations of systolic blood pressure, and serum blood urea nitrogen and creatinine levels. Conclusions: Ang-II-infusion induced an immediate fibrotic response in the heart while fibrosis in the kidney developed slowly. The cardiac fibrosis was accompanied by progressive adverse remodeling and worsening of function over time. TNFR1-KO mice were protected from the Ang-II-induced cardiac and renal fibrosis, despite similar increases in blood pressure and renal dysfunction.

Long-term effects of ACTH combined with angiotensin II on steroidogenesis and adrenal zona glomerulosa morphology in the rat

1987 ◽  
Vol 114 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Anne M. Riondel ◽  
Piera Rebuffat ◽  
Giuseppina Mazzochi ◽  
Gastone G. Nussdorfer ◽  
Rolf C. Gaillard ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Morphological Changes ◽  
Zona Glomerulosa ◽  
Zona Fasciculata ◽  
Homogeneous Population ◽  
Long Term Treatment ◽  
Acth Treatment ◽  
Glomerulosa Cells ◽  
Zona Glomerulosa Cells

Abstract. To test the hypothesis that the trophic action of angiotensin II on the adrenal zona glomerulosa may allow a sustained stimulation of aldosterone by ACTH by preventing the morphological changes of the zona glomerulosa cells into zona fasciculata-like elements we investigated the effects in rats of a 6-day treatment with ACTH (100 μg/kg/day) alone or combined with angiotensin II (300 ng/kg/day) on corticosterone and aldosterone production and adrenal morphology. The responsiveness of both steroids to an acute ACTH dose was also studied on the last day of long-term treatment. Morphologic data showed that prolonged ACTH treatment stimulated the growth of zona glomerulosa cells, though it transformed the tubulo-lamellar cristae of mitochondria into a homogeneous population of vesicles. Angiotensin II furthered the trophic effects of ACTH but prevented the mitochondrial transformation. Despite its ability to conserve the well differentiated aspect of the zona glomerulosa cells, the administration of angiotensin II was unable to prevent the fall in the secretion of aldosterone caused by chronic ACTH treatment and its subsequent unresponsiveness to ACTH stimulation.

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