Vascular Type 1A Angiotensin II Receptors Control BP by Regulating Renal Blood Flow and Urinary Sodium Excretion

Intrarenal infusion of the natural prostaglandin PGE2 increases renal blood flow, renal interstitial hydrostatic pressure, and urinary sodium excretion. A newly synthesized prostaglandin analogue, 4-3-[3-[2-(1-hydroxycyclohexyl)- ethyl]-4-oxo-2-thiazolidinyl]propyl benzoic acid, increases renal blood flow without increasing sodium excretion. To investigate the role of renal interstitial hydrostatic pressure in this dissociation, comparisons were made between PGE2 and the prostaglandin analogue. Intrarenal infusion of PGE2 increased renal blood flow, renal interstitial hydrostatic pressure, and urinary sodium excretion. Following a similar increase in renal blood flow with intrarenal infusion of prostaglandin analogue, renal interstitial hydrostatic pressure and urinary sodium excretion were not changed. To determine whether increases in urinary sodium excretion due to PGE2 infusion are causally related to the increase in renal interstitial hydrostatic pressure rather than to the increase in renal blood flow, responses to PGE2 were obtained in the absence of increases in interstitial pressure. When renal interstitial hydrostatic pressure was held constant, urinary sodium excretion did not change although there was a marked increase in renal blood flow. We conclude that increased renal interstitial hydrostatic pressure is necessary to produce an increase in urinary sodium excretion with prostaglandin-mediated renal vasodilation.

Download Full-text

Role of renal alpha-adrenoceptors mediating renin secretion

AJP Renal Physiology ◽

10.1152/ajprenal.1982.242.6.f620 ◽

1982 ◽

Vol 242 (6) ◽

pp. F620-F626 ◽

Cited By ~ 2

Author(s):

J. L. Osborn ◽

G. F. DiBona ◽

M. D. Thames

Keyword(s):

Blood Flow ◽

Renal Blood Flow ◽

Sodium Excretion ◽

Urinary Sodium Excretion ◽

Urinary Sodium ◽

Renin Secretion ◽

Renal Nerve ◽

Alpha Adrenoceptors ◽

Alpha Adrenoceptor

The increase in renin secretion resulting from low-frequency renal nerve stimulation (0.5 Hz) occurs in the absence of changes in urinary sodium excretion or renal blood flow and is apparently derived from a direct effect of renal sympathetic nerves on juxtaglomerular granular cells. We sought to determine the role of renal alpha-adrenoceptors in this neurally evoked renin secretion. The neurally evoked renin secretion was unaffected by renal alpha-adrenoceptor blockade with phentolamine or prazosin; however, two dose levels of phenoxybenzamine equally inhibited the renin secretion. The renal vasoconstrictor response to graded renal nerve stimulation was similarly diminished by phentolamine, prazosin, and the higher phenoxybenzamine dose, whereas the lower phenoxybenzamine dose was significantly less effective. Renal alpha-adrenoceptor stimulation with methoxamine infusion at doses that were just subthreshold for altering renal blood flow and urinary sodium excretion or at doses that just reduced urinary sodium excretion also did not change renin secretion. Higher doses of methoxamine that decreased both renal blood flow and sodium excretion increased renin secretion. Based on the inability of phentolamine and prazosin to prevent neurally mediated renin secretion and on the dose-response relationship between methoxamine and changes in renin secretion, renal blood flow, and urinary sodium excretion, we conclude that renal alpha-adrenoceptors do not mediate renin secretion elicited by direct neural activation of the juxtaglomerular granular cells. The data suggest that phenoxybenzamine inhibits neurally mediated renin secretion by a mechanism other than renal alpha-adrenoceptor blockade.

Download Full-text

Vascular type 1A angiotensin II receptors regulate renal blood flow and natriuresis

Nature Reviews Nephrology ◽

10.1038/nrneph.2015.69 ◽

2015 ◽

Vol 11 (6) ◽

pp. 318-318 ◽

Cited By ~ 1

Author(s):

Ellen F. Carney

Keyword(s):

Blood Flow ◽

Angiotensin Ii ◽

Renal Blood Flow ◽

Angiotensin Ii Receptors ◽

Vascular Type

Download Full-text

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

Journal of the Renin-Angiotensin-Aldosterone System ◽

10.1177/1470320311408750 ◽

2011 ◽

Vol 12 (4) ◽

pp. 394-403 ◽

Cited By ~ 22

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.

Download Full-text

Sodium appetite elicited by intracerebroventricular infusion of angiotensin II in the rat: I. Relation to urinary sodium excretion.

Behavioral Neuroscience ◽

10.1037/0735-7044.97.5.738 ◽

1983 ◽

Vol 97 (5) ◽

pp. 738-745 ◽

Cited By ~ 40

Author(s):

Steven J. Fluharty ◽

Scott Manaker

Keyword(s):

Angiotensin Ii ◽

Sodium Excretion ◽

Urinary Sodium Excretion ◽

Urinary Sodium ◽

Sodium Appetite ◽

Intracerebroventricular Infusion

Download Full-text

Verapamil prevents insulin antinatriuresis in euglycemic rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1992.262.6.r1145 ◽

1992 ◽

Vol 262 (6) ◽

pp. R1145-R1148 ◽

Cited By ~ 2

Author(s):

A. K. Gupta ◽

R. Clark ◽

K. A. Kirchner

Keyword(s):

Angiotensin Ii ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Sodium Excretion ◽

Urinary Sodium Excretion ◽

Calcium Entry ◽

Urinary Sodium ◽

Inulin Clearance ◽

Insulin Administration ◽

Lower Baseline

To determine whether calcium entry is necessary for insulin antinatriuresis, urinary sodium excretion was determined before and during euglycemic insulin administration in rats receiving verapamil (10 micrograms.kg-1.min-1) or vehicle. In vehicle rats, insulin reduced sodium excretion from 2.7 +/- 0.5 to 0.98 +/- 0.2 mu eq/min (P less than 0.05) without altering arterial pressure or inulin clearance. Insulin did not reduce sodium excretion in rats receiving verapamil. Baseline mean arterial pressure was lower in verapamil rats than in vehicle rats. To exclude the possibility that lower baseline arterial pressures prevented insulin antinatriuresis, insulin's effect on sodium excretion was determined in rats receiving captopril at a dose that reduced arterial pressure to the level observed in verapamil rats, and in verapamil rats with angiotensin II levels fixed to maintain arterial pressure equivalent to vehicle rats. In captopril rats, insulin reduced (P less than 0.05) sodium excretion from 1.07 +/- 0.3 to 0.3 +/- 0.01 mu eq/min, even though arterial pressure was not different from that in verapamil rats. Insulin failed to reduce sodium excretion in verapamil rats receiving angiotensin II. Thus verapamil prevents insulin antinatriuresis by renal mechanisms related to inhibition of calcium entry. Additionally, insulin antinatriuresis is independent of angiotensin II.

Download Full-text

Effect of a kinin antagonist on renal function and haemodynamics during alterations in sodium balance in conscious normotensive rats

Clinical Science ◽

10.1042/cs0780165 ◽

1990 ◽

Vol 78 (2) ◽

pp. 165-168 ◽

Cited By ~ 6

Author(s):

Paolo Madeddu ◽

Nicola Glorioso ◽

Aldo Soro ◽

Paolo Manunta ◽

Chiara Troffa ◽

...

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Renal Function ◽

Glomerular Filtration Rate ◽

Glomerular Filtration ◽

Renal Blood Flow ◽

Sodium Excretion ◽

Filtration Rate ◽

Sodium Intake ◽

Urinary Sodium Excretion

1. To evaluate whether sodium intake can modulate the action of endogenous kinins on renal function and haemodynamics, a receptor antagonist of bradykinin was infused in conscious normotensive rats maintained on either a normal or a low sodium diet. 2. The antagonist inhibited the hypotensive effect of exogenously administered bradykinin. It did not change the vasodepressor effect of acetylcholine, dopamine or prostaglandin E2. 3. The antagonist did not affect mean blood pressure, glomerular filtration rate, renal blood flow or urinary sodium excretion, in rats on sodium restriction. It did not change mean blood pressure, glomerular filtration rate or urinary sodium excretion, but decreased renal blood flow, in rats on a normal sodium intake. 4. The kallikrein–kinin system has a role in the regulation of renal blood flow in rats on a normal sodium diet.

Download Full-text

Angiotensin II and Not Sodium Status is the Major Determinant of the Agonistic/Antagonistic Balance of Saralasin's Actions

Clinical Science ◽

10.1042/cs059075s ◽

1980 ◽

Vol 59 (s6) ◽

pp. 75s-78s ◽

Cited By ~ 3

Author(s):

R. Fagard ◽

A. Amery ◽

P. Lijnen

Keyword(s):

Angiotensin Ii ◽

Sodium Excretion ◽

Sodium Intake ◽

Plasma Renin ◽

Urinary Sodium Excretion ◽

Urinary Sodium ◽

Plasma Angiotensin ◽

Group 3 ◽

Group 2 ◽

Group 1

1. To study which factors determine the balance between the antagonistic and agonistic effects of the angiotensin II analogue [Sar1,Ala8]-angiotensin II (saralasin) in man, saralasin was infused in subjects on a ‘normal’ sodium intake (group 1) during sodium restriction with appropriately elevated plasma angiotensin II levels (group 2) and in sodium-restricted subjects in whom plasma angiotensin II was suppressed by converting enzyme inhibition with captopril (group 3). 2. The action of saralasin was agonistic in group 3, antagonistic in group 2 and variable in group 1. 3. For groups 1 and 2 together the saralasin-induced changes of arterial pressure, of plasma aldosterone and of plasma renin were significantly related to control plasma angiotensin II but also to the 24 h urinary sodium excretion. When group 3 was included the changes remained significantly related to plasma angiotensin II but not to the urinary sodium excretion. 4. The results indicate that angiotensin II and not sodium status determines the agonistic/antagonistic balance of saralasin's actions.

Download Full-text

Relaxin-induced changes in renal sodium excretion in the anesthetized male rat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00509.2004 ◽

2005 ◽

Vol 288 (1) ◽

pp. R322-R328 ◽

Cited By ~ 20

Author(s):

Alsadek H. Bogzil ◽

Rachel Eardley ◽

Nick Ashton

Keyword(s):

Blood Flow ◽

Renal Blood Flow ◽

Sodium Excretion ◽

Plasma Osmolality ◽

Urinary Sodium Excretion ◽

Male Rats ◽

Male Rat ◽

Short Term ◽

Induced Changes

Pregnancy is associated with profound changes in renal hemodynamics and electrolyte handling. Relaxin, a hormone secreted by the corpus luteum, has been shown to induce pregnancy-like increases in renal blood flow and glomerular filtration rate (GFR) and alter osmoregulation in nonpregnant female and male rats. However, its effects on renal electrolyte handling are unknown. Accordingly, the influence of short (2 h)- and long-term (7 day) infusion of relaxin on renal function was determined in the male rat. Short term infusion of recombinant human relaxin (rhRLX) at 4 μg·h−1·100 g body wt−1 induced a significant increase in effective renal blood flow (ERBF) within 45 min, which peaked at 2 h of infusion (vehicle, n = 6, 2.1 ± 0.4 vs. rhRLX, n = 7, 8.1 ± 1.1 ml·min−1·100 g body wt−1, P < 0.01). GFR and urinary excretion of electrolytes were unaffected. After a 7-day infusion of rhRLX at 4 μg/h, ERBF (1.4 ± 0.2 vs. 2.5 ± 0.4 ml·min−1·100 g body wt−1, P < 0.05), urine flow rate (3.1 ± 0.3 vs. 4.3 ± 0.4 μl·min−1·100 g body wt−1, P < 0.05) and urinary sodium excretion (0.8 ± 0.1 vs. 1.2 ± 0.1 μmol·min−1·100 g body wt−1, P < 0.05) were significantly higher; plasma osmolality and sodium concentrations were lower in rhRLX-treated rats. These data show that long-term relaxin infusion induces a natriuresis and diuresis in the male rat. The mechanisms involved are unclear, but they do not involve changes in plasma aldosterone or atrial natriuretic peptide concentrations.

Download Full-text