Chronic ouabain infusion does not cause hypertension in sheep

1996 ◽  
Vol 270 (3) ◽  
pp. E386-E392 ◽  
Author(s):  
G. B. Pidgeon ◽  
A. M. Richards ◽  
M. G. Nicholls ◽  
C. J. Charles ◽  
M. T. Rademaker ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Urine Volume ◽  
Plasma Renin ◽  
Urinary Sodium Excretion ◽  
Dietary Sodium ◽  
High Dose ◽  
Urine Electrolytes ◽  
Conscious Sheep ◽  
Sodium And Potassium

Ouabain is claimed to be a hormone of adrenal origin, capable of raising arterial pressure in rats. We infused ouabain in conscious sheep under carefully controlled circumstances to determine its effects on blood pressure, urine electrolytes, and vasoactive hormones. Eight healthy ewes were studied while taking a constant intake of dietary sodium and potassium. Ouabain infusion at 0.25 mg daily over 22 days reduced heart rate and arterial pressure and had no effect on pressor responsiveness to incremental intravenous infusions of angiotensin II. Ouabain induced minor, but statistically significant, decrements in urine volume, urinary sodium excretion, plasma renin and angiotensin II concentrations, and a rise in plasma aldosterone and cortisol. Plasma ouabain levels averaged 1.37 +/- 0.28 nmol/l during ouabain infusion. In conclusion, high-dose chronic ouabain infusion in sheep did not elevate arterial pressure or alter pressor responsiveness to angiotensin II, was antidiuretic and antinatriuretic, and induced minor perturbations in circulating renin, angiotensin II, aldosterone, and cortisol.

Acute and chronic actions of bradykinin on renal function and arterial pressure

1985 ◽  
Vol 248 (1) ◽  
pp. F87-F92 ◽  
Author(s):  
J. P. Granger ◽  
J. E. Hall
Keyword(s):  
Arterial Pressure ◽  
Renal Plasma Flow ◽  
Urine Volume ◽  
Plasma Renin ◽  
Urinary Sodium Excretion ◽  
Renal Perfusion ◽  
Acute Effects ◽  
Plasma Aldosterone Concentration ◽  
Control Value ◽  
Renal Vascular

The present study was designed to examine the acute and chronic effects of increased levels of circulating bradykinin (BK) on control of renal hemodynamics, electrolyte excretion, and arterial pressure. Intrarenal infusion of BK (50 ng X kg-1 X min-1) for 60 min in five anesthetized dogs with renal perfusion pressure maintained at a constant level of 108 +/- 1 mmHg had no significant effect on glomerular filtration rate (GFR), whereas it increased renal blood flow (RBF) from a control value of 230 +/- 14 to 282 +/- 18, 266 +/- 15, and 253 +/- 17 ml/min after 15, 30, and 60 min of infusion, respectively. Acute intrarenal infusion of BK also increased urine volume (UV) from 0.255 +/- 0.044 to 0.523 +/- 0.103 ml/min and urinary sodium excretion (UNaV) from 5.72 +/- 1.5 to 13.7 +/- 3.4 mueq/min. To determine whether the potent acute effects of BK on RBF, UV, and UNaV lead to a chronic reduction in arterial pressure, BK (50 ng X kg-1 X min-1) was infused intrarenally for 7 days in conscious dogs. Intrarenal infusion of BK for 7 days had no significant effect on GFR, UNaV, UV, or arterial pressure. However, BK elevated renal plasma flow and decreased renal vascular resistance throughout the 7 days of infusion. Chronic intrarenal BK infusion caused no significant changes in plasma renin activity or plasma aldosterone concentration. Results from these studies indicate that although increased levels of bradykinin in the renal circulation can have potent acute effects on RBF, UV, and UNaV, these effects on UV and UNaV are not sustained and therefore do not result in long-term changes in arterial pressure.

Angiotensin Blockade in Studies of the Feedback Control of Renin Release in Rats and Rabbits

1974 ◽  
Vol 48 (s2) ◽  
pp. 33s-36s
Author(s):  
G. S. Stokes ◽  
Helen F. Oates ◽  
M. A. Weber
Keyword(s):  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Feedback Loop ◽  
Plasma Renin ◽  
Renin Secretion ◽  
Negative Feedback Loop ◽  
High Dose ◽  
Plasma Renin Concentration ◽  
Anaesthetized Rats ◽  
Angiotensin Blockade

1. In rabbits actively immunized against angiotensin II (AII), the appearance of anti-AII antibodies was associated with a rise in plasma renin activity (PRA), which did not occur in mock-immunized controls. 2. In conscious rabbits, infusion of the angiotensin inhibitor, Sar1-Ala8-angiotensin II (P-113), at rates of 0.055, 0.22 or 1.1 nmol min−1 kg−1 into the renal artery, caused dose-related increases in arterial PRA and renal arteriovenous PRA difference. Renal blood flow fell with the high dose, but not with the low or medium doses. A fall in arterial pressure, asynchronous with peak renin secretion, accompanied the medium- and high-dose infusions. 3. Intravenous infusion of inhibitor P-113, 5.5 nmol min−1 kg−1, into anaesthetized rats produced highly significant increases in PRA and plasma renin concentration without reduction in arterial pressure. There were no changes in PRA or plasma renin concentration in saline-infused control rats. 4. These findings suggest that AII blockade interrupts a negative feedback loop controlling renin secretion.

Brain angiotensinergic pathways mediate renal nerve inhibition by central hypertonic NaCl in conscious sheep

1997 ◽  
Vol 272 (2) ◽  
pp. R593-R600 ◽  
Author(s):  
C. N. May ◽  
R. M. McAllen
Keyword(s):  
Arterial Pressure ◽  
Hypertonic Saline ◽  
Diastolic Pressure ◽  
Venous Pressure ◽  
Chloride Concentration ◽  
Plasma Renin ◽  
Renal Nerve ◽  
Intracerebroventricular Infusion ◽  
Conscious Sheep ◽  
Renal Sympathetic

The renal sympathetic responses to infusion of hypertonic solutions into the lateral cerebral ventricles were investigated in conscious sheep. Intracerebroventricular infusion of artificial cerebrospinal fluid (CSF) containing 0.6 M NaCl, at 1 ml/h for 20 min, reduced renal sympathetic nerve activity (RSNA) by 81 +/- 5% (n = 6, P < 0.001). Plasma renin concentration also fell (P < 0.05), whereas arterial pressure increased by 6.4 +/- 0.7 mmHg (P < 0.01). Intracerebroventricular hypertonic sorbitol (0.9 M in CSF at 1 ml/h) had no effect. The AT1 receptor antagonist losartan (1 mg/h) abolished the plasma renin and arterial pressure responses to intracerebroventricular hypertonic saline and significantly reduced the fall in RSNA to 17 +/- 10% (P < 0.001). During intracerebroventricular hypertonic saline, the baroreflex relation of RSNA to diastolic pressure was shifted to the left and that to central venous pressure was abolished compared with control relations obtained by manipulating pressure with intravenous phenylephrine. These findings indicate that 1) RSNA is inhibited by a central mechanism that senses high sodium (or perhaps chloride) concentration rather than hypertonicity; 2) this inhibition occurs independently of reflexes from high- and low-pressure baroreceptors, although these may enhance the inhibition; and 3) inhibition of RSNA by hypertonic saline involves a central angiotensinergic pathway.

L-arginine analogues inhibit aldosterone secretion in rats

1995 ◽  
Vol 268 (5) ◽  
pp. R1137-R1142 ◽  
Author(s):  
J. C. Simmons ◽  
R. H. Freeman
Keyword(s):  
Blood Flow ◽  
Angiotensin Ii ◽  
Methyl Ester ◽  
Arterial Pressure ◽  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Renin Activity ◽  
Bilateral Nephrectomy ◽  
Aldosterone Secretion ◽  
Series Of Experiments

L-Arginine analogues, e.g., NG-nitro-L-arginine methyl ester (L-NAME), increase arterial pressure and suppress renin release in the rat. On the basis of these observations, it was hypothesized that L-arginine analogues also would attenuate aldosterone secretion. This hypothesis was tested in anesthetized rats treated with L-NAME or NG-nitro-L-arginine (L-NNA, 185 mumol/kg ip). The aldosterone secretion rate, plasma renin activity, and adrenal blood flow were attenuated in rats treated with L-NAME and L-NNA compared with control animals. Similar experiments were performed in anephric rats to examine the effects of L-NAME on aldosterone secretion independent of the circulating reninangiotensin system. The administration of L-NAME reduced adrenal blood flow but failed to reduce aldosterone secretion in these anephric rats. Bilateral nephrectomy reduced plasma renin activity essentially to undetectable levels in these animals. In a third series of experiments, two groups of anephric rats were infused with angiotensin II (3 micrograms/kg body wt iv) to provide a stimulus for aldosterone secretion. Aldosterone secretion and adrenal blood flow were markedly reduced in angiotensin II-infused rats pretreated with L-NAME compared with the control anephric animals infused with angiotensin II. Overall these results suggest that L-arginine analogues attenuate aldosterone secretion by inhibiting the adrenal steroidogenic effects of endogenous or exogenous angiotensin II and/or by reducing plasma levels of renin/angiotensin.

Steady-state arterial pressure-urinary output relationships during ovine pregnancy

1992 ◽  
Vol 263 (5) ◽  
pp. R1141-R1146
Author(s):  
E. W. Quillen ◽  
B. S. Nuwayhid
Keyword(s):  
Renal Function ◽  
Steady State ◽  
Arterial Pressure ◽  
Sodium Intake ◽  
Control Level ◽  
Urine Volume ◽  
Urinary Sodium Excretion ◽  
Pregnant Sheep ◽  
Plasma Angiotensin ◽  
Steady State Levels

To determine the effects of long-term changes in sodium intake on mean arterial pressure (MAP) regulation during pregnancy, nonpregnant (n = 16) and 110- to 140-day pregnant (n = 13) ewes received total daily sodium intakes of 10, 30, 100, 400, and 1,200 mmol for 7 days. The sheep were housed in metabolism cages and MAP was monitored 24 h/day. Urinary sodium excretion (UNaV) followed changes in sodium intake, with steady-state levels being achieved with similar degrees of rapidity (2-3 days) in nonpregnant and pregnant sheep. At 10 mmol/day sodium intake, MAP was lower (79 +/- 1 vs. 82 +/- 2 mmHg; P < 0.01) and water intake (2,275 +/- 494 vs. 3,286 +/- 725 ml/day; P < 0.001) and 24-h urine volume (1,454 +/- 279 vs. 2,299 +/- 496 ml/day; P < 0.01) were greater in pregnant sheep. All of these variables exhibited direct relationships with increases in sodium intake. Plasma angiotensin II (pANG II) was increased in pregnancy (10.6 +/- 1.6 vs. 24.5 +/- 6.3 pg/ml; P < 0.001) at 10 mmol/day. Elevation of sodium intake suppressed pANG II to minimal levels in nonpregnant sheep, but to only 25% of the control level in pregnant sheep. During pregnancy, the renal function curve representing the steady-state MAP-UNaV relationship was shifted to lower MAP setpoint, but the sodium sensitivity of MAP was unchanged. Also, the inverse relationship of sodium intake and pANG II was blunted, suggesting a reduced role for ANG II in the maintenance of renal function during pregnancy.

Natriuretic peptide analogues with distinct vasodilatory or renal activity: integrated effects in health and experimental heart failure

2020 ◽  
Author(s):  
Miriam T Rademaker ◽  
Nicola J A Scott ◽  
Cho Yeow Koh ◽  
R Manjunatha Kini ◽  
A Mark Richards
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Natriuretic Peptide ◽  
Acute Decompensated Heart Failure ◽  
Unmet Need ◽  
Urine Volume ◽  
Plasma Renin ◽  
Decompensated Heart Failure ◽  
Guanosine Monophosphate ◽  
High Dose

Abstract Aims Management of acute decompensated heart failure (ADHF) requires disparate treatments depending on the state of systemic/peripheral perfusion and the presence/absence of expanded body–fluid volumes. There is an unmet need for therapeutics that differentially treat each aspect. Atrial natriuretic peptide (ANP) plays an important role in blood pressure and volume regulation. We investigate for the first time the integrated haemodynamic, endocrine and renal effects of human ANP analogues, modified for exclusive vasodilatory (ANP-DRD) or diuretic (ANP-DGD) activities, in normal health and experimental ADHF. Methods and results We compared the effects of incremental infusions of ANP analogues ANP-DRD and ANP-DGD with native ANP, in normal (n = 8) and ADHF (n = 8) sheep. ANP-DRD administration increased plasma cyclic guanosine monophosphate (cGMP) in association with dose-dependent reductions in arterial pressure in normal and heart failure (HF) sheep similarly to ANP responses. In contrast to ANP, which in HF produced a diuresis/natriuresis, this analogue was without significant renal effect. Conversely, ANP-DGD induced marked stepwise increases in urinary cGMP, urine volume, and sodium excretion in HF comparable to ANP, but without accompanying vasodilatory effects. All peptides increased packed cell volume relative to control in both states, and in HF, decreased left atrial pressure. In response to ANP-DRD-induced blood pressure reductions, plasma renin activity rose compared to control only during the high dose in normals, and not at all in HF—suggesting relative renin inhibition, with no increase in aldosterone in either state, whereas renin and aldosterone were both significantly reduced by ANP-DGD in HF. Conclusion These ANP analogues exhibit distinct vasodilatory (ANP-DRD) and diuretic/natriuretic (ANP-DGD) activities, and therefore have the potential to provide precision therapy for ADHF patients with differing pathophysiological derangement of pressure–volume homeostasis.

Effects of blockade of brain angiotensin II receptors in conscious, sodium-deprived dogs

1983 ◽  
Vol 245 (6) ◽  
pp. R881-R887 ◽  
Author(s):  
V. L. Brooks ◽  
I. A. Reid
Keyword(s):  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Intravenous Infusion ◽  
Plasma Renin ◽  
Hypotensive Effect ◽  
Similar Degree ◽  
Central Action ◽  
Ang Ii ◽  
Sodium Deficiency ◽  
Low Sodium Diet

The present studies were designed to evaluate the physiological significance of the actions of angiotensin II (ANG II) on the brain. The effects of blockade of brain ANG II receptors by intracarotid or intravertebral infusions of saralasin were studied in conscious dogs with high circulating ANG II levels (142 +/- 16 pg/ml) due to a low-sodium diet. Three doses of saralasin were infused into each pair of arteries and intravenously: 0.1, 0.3, and 1.0 micrograms X kg-1 X min-1. Saralasin produced dose-related decreases in arterial pressure during infusion into the carotid or vertebral arteries, confirming that ANG II maintains arterial pressure during sodium deficiency. However, intravenous saralasin administration decreased pressure to a similar degree, suggesting that the hypotensive effect was due to recirculation of saralasin, rather than to blockade of a central action of circulating ANG II. Heart rate was not altered by infusion of saralasin by any route. Saralasin administration also caused a dose-dependent increase in plasma renin activity and plasma ANG II concentration. However, because the increases produced by intracarotid or intravertebral saralasin did not differ from the increase produced by intravenous infusion, these results do not provide evidence that renin release is modulated by a central action of ANG II during sodium deficiency. Plasma corticosteroid levels were reduced (2.4 +/- 0.5 to 1.4 +/- 0.2 micrograms/dl, P less than 0.05) by intravenous infusion of the highest dose of saralasin, but neither intracarotid nor intravertebral saralasin infusion altered plasma corticosteroid concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Lack of an effect of collecting duct-specific deletion of adenylyl cyclase 3 on renal Na+ and water excretion or arterial pressure

2014 ◽  
Vol 306 (6) ◽  
pp. F597-F607 ◽  
Author(s):  
Wararat Kittikulsuth ◽  
Deborah Stuart ◽  
Alfred N. Van Hoek ◽  
James D. Stockand ◽  
Vladislav Bugaj ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Adenylyl Cyclase ◽  
Collecting Duct ◽  
Urine Volume ◽  
Physiological Role ◽  
Plasma Renin ◽  
Water Restriction ◽  
Water Excretion ◽  
And Control

cAMP is a key mediator of connecting tubule and collecting duct (CD) Na+ and water reabsorption. Studies performed in vitro have suggested that CD adenylyl cyclase (AC)3 partly mediates the actions of vasopressin; however, the physiological role of CD AC3 has not been determined. To assess this, mice were developed with CD-specific disruption of AC3 [CD AC3 knockout (KO)]. Inner medullary CDs from these mice exhibited 100% target gene recombination and had reduced ANG II- but not vasopressin-induced cAMP accumulation. However, there were no differences in urine volume, urinary urea excretion, or urine osmolality between KO and control mice during normal water intake or varying degrees of water restriction in the presence or absence of chronic vasopressin administration. There were no differences between CD AC3 KO and control mice in arterial pressure or urinary Na+ or K+ excretion during a normal or high-salt diet, whereas plasma renin and vasopressin concentrations were similar between the two genotypes. Patch-clamp analysis of split-open cortical CDs revealed no difference in epithelial Na+ channel activity in the presence or absence of vasopressin. Compensatory changes in AC6 were not responsible for the lack of a renal phenotype in CD AC3 KO mice since combined CD AC3/AC6 KO mice had similar arterial pressure and renal Na+ and water handling compared with CD AC6 KO mice. In summary, these data do not support a significant role for CD AC3 in the regulation of renal Na+ and water excretion in general or vasopressin regulation of CD function in particular.

Lithium pretreatment affects renal and systemic responses to angiotensin II infusion in normal man

1992 ◽  
Vol 82 (5) ◽  
pp. 543-549 ◽  
Author(s):  
D. W. Eadington ◽  
S. Freestone ◽  
C. J. Waugh ◽  
C. P. Swainson ◽  
M. R. Lee
Keyword(s):  
Angiotensin Ii ◽  
Sodium Excretion ◽  
Plasma Renin ◽  
Lithium Carbonate ◽  
Urinary Sodium Excretion ◽  
Plasma Aldosterone Concentration ◽  
Normal Man ◽  
Normal Males ◽  
Renal Vascular ◽  
Systemic Responses

1. Renal and systemic responses to infusion of angiotensin II (1.25 and 2.5 ng min−1 kg−1 body weight) were examined in ten normal males 12 h after single doses of 750 mg of lithium carbonate, 250 mg of lithium carbonate (n = 6) or placebo. 2. Baseline mean arterial pressure [mean (sem)] was higher after 750 mg of lithium [93.1 (1.7) versus 89.5 (1.9) mmHg, P = 0.014], and the subsequent rise in blood pressure during angiotensin II infusion was lower [8.2 (1.8) versus 12.2 (2.4) mmHg, P < 0.02]. 3. Lithium at a dose of 750 mg increased overnight urinary sodium excretion before the study. The fall in fractional sodium excretion during angiotensin II infusion was reduced after pretreatment with 750 mg of lithium [750 mg of lithium, 2.73 (0.24) to 1.34 (0.08)%; placebo, 2.69 (0.26) to 1.01 (0.11)%; P=0.02]. The increases in effective filtration fraction [750 mg of lithium, 5.4 (1.0)%; placebo, 8.6 (0.7)%; P < 0.05] and total effective renal vascular resistance [750 mg of lithium, 3700 (390) dyn s cm−5; placebo 5100 (460) dyn s cm−5; P=0.03] during angiotensin II infusion were also attenuated after 750 mg of lithium. Responses after 250 mg of lithium did not differ from those after placebo. 4. The fall in plasma renin activity and the increase in plasma aldosterone concentration during angiotensin II infusion were similar on each study day. 5. Renal responses to exogenous angiotensin II are altered after pretreatment with a 750 mg dose of lithium in normal man. This dose of lithium is not an inert marker of sodium handling.

scholarly journals Increased thromboxane mediates the adverse renal effects of interleukin-2 in rats.

1994 ◽  
Vol 4 (9) ◽  
pp. 1701-1710
Author(s):  
D Rubinger ◽  
E Cohen ◽  
Y Haviv ◽  
J Bernheim ◽  
E Shiloni ◽  
...  
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Low Dose ◽  
Combined Therapy ◽  
Interleukin 2 ◽  
Chronic Administration ◽  
Urinary Sodium Excretion ◽  
Metabolic Effects ◽  
High Dose ◽  
Sodium And Potassium

The capillary leak syndrome with decreased GFR and renal water and sodium retention after recombinant interleukin-2 (IL-2) administration may arise from endothelial activation via an increase in prostaglandin synthesis. This study was undertaken to better define the role of the prostaglandin system in the renal and metabolic effects of IL-2 administration in rats. The chronic administration of IL-2 (100,000 U/kg, thrice daily, ip) resulted in a significant increase in body weight, a decrease in GFR and in the urinary excretion of sodium and potassium, and an increase in the urinary excretion of thromboxane (TXB2). After combined IL-2 and low-dose indomethacin (1.7 mg/kg per day po), a significant decrease in body weight with normalization of GFR, of the urinary excretion of Na, and of urinary TXB2 was noted in animals receiving combined therapy as compared with those receiving IL-2 alone. In contrast, high-dose indomethacin administration (33.3 mg/kg po for the last 3 days of the study) was associated with a further decrease in GFR, enhancement of the sodium and potassium retention, and suppression of prostaglandin E2 excretion. The administration of the thromboxane receptor antagonist SQ 29548 in IL-2-treated rats led to a reversal of the fall in GFR induced by the lymphokine without significant changes in urinary sodium excretion. These results support the hypothesis that thromboxane is an important mediator of the renal and systemic effects of IL-2. These effects are reversed at least partly by low-dose indomethacin, which selectively suppresses thromboxane A2 (TXA2) synthesis, or by TXA2 receptor antagonism.

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