The increase in renal sodium excretion in response to Angiotensin II infusion in exercised female rats is dependent on a rise in renal perfusion pressure.

An adaptation of the in vitro perfused hydronephrotic rat kidney model allowing in situ measurement of arteriolar membrane potentials is described. At a renal perfusion pressure of 80 mmHg, resting membrane potentials of interlobular arteries (22 +/- 2 microns) and afferent (14 +/- 1 microns) and efferent arterioles (12 +/- 1 microns) were -40 +/- 2 (n = 8), -40 +/- 1 (n = 45), and -38 +/- 2 mV (n = 22), respectively (P = 0.75). Using a dual-pipette system to stabilize the impalement site, we measured afferent and efferent arteriolar membrane potentials during angiotensin II (ANG II)-induced vasoconstriction. ANG II (0.1 nM) reduced afferent arteriolar diameters from 13 +/- 1 to 8 +/- 1 microns (n = 8, P = 0.005) and membrane potentials from -40 +/- 2 to -29 +/- mV (P = 0.012). ANG II elicited a similar vasoconstriction in efferent arterioles, decreasing diameters from 13 +/- 1 to 8 +/- 1 microns (n = 8, P = 0.004), but failed to elicit a significant depolarization (-39 +/- 2 for control; -36 +/- 3 mV for ANG II; P = 0.27). Our findings thus indicate that resting membrane potentials of pre- and postglomerular arterioles are similar and lie near the threshold activation potential for L-type Ca channels. ANG II-induced vasoconstriction appears to be closely coupled to membrane depolarization in the afferent arteriole, whereas mechanical and electrical responses appear to be dissociated in the efferent arteriole.

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Renal perfusion pressure and renin secretion in bilaterally renal denervated sheep

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y94-111 ◽

1994 ◽

Vol 72 (7) ◽

pp. 782-787 ◽

Cited By ~ 10

Author(s):

L. Fan ◽

S. Mukaddam-Daher ◽

J. Gutkowska ◽

B. S. Nuwayhid ◽

E. W. Quillen Jr.

Keyword(s):

Angiotensin Ii ◽

Atrial Natriuretic Factor ◽

Perfusion Pressure ◽

Excretion Rate ◽

Plasma Renin ◽

Renal Perfusion ◽

Renin Secretion ◽

Renal Nerves ◽

Renal Perfusion Pressure ◽

Plasma Angiotensin

To further investigate the influence of renal nerves on renin secretion, the renin secretion responses to step reductions of renal perfusion pressure (RPP) were studied in conscious sheep with innervated kidneys (n = 5) and with bilaterally denervated kidneys (n = 5). The average basal level of RPP in sheep with denervated kidneys (82 ± 4 mmHg; 1 mmHg = 133.3 Pa) was similar to that in sheep with innervated kidneys (83 ± 3 mmHg). RPP was reduced in four sequential 15-min steps, to a final level of 54 ± 2 mmHg in sheep with innervated kidneys and to 57 ± 1 mmHg in denervated sheep. The renin secretion rate was increased as RPP was reduced in sheep with innervated kidneys. Baseline peripheral plasma renin activity was reduced and there was almost no response of renin secretion rate to reduction of RPP in sheep with denervated kidneys. Also, baseline renal blood flow, urine flow rate, sodium excretion rate, and potassium excretion rate were higher in sheep with denervated kidneys than those with innervated kidneys. Baseline plasma angiotensin II was similar in both groups of sheep. As RPP was decreased, plasma angiotensin II was increased in sheep with innervated kidneys, but was not significantly altered in sheep with denervated kidneys. Plasma atrial natriuretic factor was unaltered by either reduction of RPP or renal denervation. In conclusion, hormonal factors, such as angiotensin II and atrial natriuretic factor, do not account for the dramatic suppression of renin secretion in response to the reduction of RPP in sheep with bilateral renal denervation. Renal nerves are a necessary component in the control of renin secretion during reduction of RPP and may contribute to the regulation of baseline plasma renin activity and sodium excretion rate in conscious ewes.Key words: renin secretion, renal perfusion pressure, renal nerves, denervation, sheep.

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ACE inhibition prevents Na and water retention and MABP increase during reduction of renal perfusion pressure

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.269.3.r481 ◽

1995 ◽

Vol 269 (3) ◽

pp. R481-R489 ◽

Cited By ~ 3

Author(s):

W. Boemke ◽

E. Seeliger ◽

L. Rothermund ◽

M. Corea ◽

R. Pettker ◽

...

Keyword(s):

Angiotensin Ii ◽

Angiotensin Converting Enzyme ◽

Water Retention ◽

Perfusion Pressure ◽

Renal Perfusion ◽

Plasma Aldosterone ◽

Angiotensin Converting Enzyme Inhibition ◽

Converting Enzyme ◽

Renal Perfusion Pressure ◽

Arterial Blood

Two groups of six dogs were studied during 4 control days and 4 days of reduced renal perfusion pressure (rRPP) servo controlled at 20% below the individual dog's 24-h mean arterial blood pressure (MABP) during control days, i.e., below the threshold for renin release. On rRPP days, endogenous activation of plasma aldosterone and angiotensin II was inhibited by the angiotensin-converting enzyme inhibitor captopril. The dogs were kept on a high-Na and high-water intake. Unlike studies during rRPP alone, there was no Na and water retention during rRPP+captopril. Glomerular filtration rate dropped by approximately 9%, and MABP remained in the range of control days. Plasma renin activity rose to values 14 times greater than control, whereas plasma aldosterone decreased by approximately 60%. Atrial natriuretic peptide remained in the range of controls. In conclusion, angiotensin-converting enzyme inhibition can prevent the otherwise obligatory Na and water retention and systemic MABP increase during a 20% reduction in renal perfusion pressure. This is achieved most likely via the captopril-induced fall in angiotensin II and plasma aldosterone levels.

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Modulation of natriuresis by sympathetic nerves and angiotensin II in conscious dogs

AJP Renal Physiology ◽

10.1152/ajprenal.1989.256.3.f485 ◽

1989 ◽

Vol 256 (3) ◽

pp. F485-F489

Author(s):

P. B. Persson ◽

H. Ehmke ◽

U. Kogler ◽

H. Kirchheim

Keyword(s):

Angiotensin Ii ◽

Sodium Excretion ◽

Perfusion Pressure ◽

Recovery Period ◽

Sympathetic Nerves ◽

Renal Perfusion ◽

Ang Ii ◽

Sympathetic Nerve Stimulation ◽

Converting Enzyme Inhibition ◽

Pressure Independent

The effects of renal perfusion pressure and reflex sympathetic nerve stimulation on sodium excretion were studied in six conscious foxhounds on a normal sodium diet. This was done before, during common carotid occlusion (CCO), and during a recovery period following CCO. Three protocols were used 1) control (n = 6), 2) converting-enzyme inhibition (CEI, n = 6), and 3) CEI combined with a constant renal artery pressure (RAP, n = 5). In protocol 1, CCO increased RAP markedly (140.5 +/- 5.1 vs. 103.0 +/- 4.4 mmHg; P less than 0.001) along with a considerable natriuresis (128.4 +/- 20.1 vs. 86.3 +/- 15.1 mumol Na+/min; P less than 0.05). In protocol 2, CEI increased control sodium excretion but did not impair the natriuresis by CCO. Maintaining RAP at control levels in protocol 3 lead to an antinatriuresis (53.1 +/- 16.8 vs. 128.3 +/- 32.2 mumol Na+/min; P less than 0.05). Creatinine clearance was unaffected by all procedures. In conclusion, a change in ANG II formation shifts but does not impair the natriuretic response to CCO. A moderate sympathetic activation has a pronounced pressure-independent antinatriuretic effect, which is not mediated by angiotensin II.

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Interaction of renal beta 1-adrenoceptors and prostaglandins in reflex renin release

AJP Renal Physiology ◽

10.1152/ajprenal.1983.244.4.f418 ◽

1983 ◽

Vol 244 (4) ◽

pp. F418-F424 ◽

Cited By ~ 3

Author(s):

U. Kopp ◽

G. F. DiBona

Keyword(s):

Sodium Excretion ◽

Perfusion Pressure ◽

Carotid Sinus ◽

Urinary Sodium Excretion ◽

Renal Perfusion ◽

Prostaglandin Synthesis ◽

Urinary Sodium ◽

Secretion Rate ◽

Renin Secretion ◽

Renal Perfusion Pressure

Anesthetized dogs with isolated carotid sinus preparation were used to examine the mechanisms involved in the increase in renin secretion rate produced by carotid baroreceptor reflex renal nerve stimulation (RNS) at constant renal perfusion pressure. Lowering carotid sinus pressure by 41 +/- 5 mmHg for 10 min increased mean arterial pressure and heart rate, caused no or minimal renal hemodynamic changes, decreased urinary sodium excretion, and increased renin secretion rate. Metoprolol, a beta 1-adrenoceptor antagonist, given in the renal artery, did not affect the decrease in urinary sodium excretion but attenuated the increase in renin secretion rate, from 1,764 +/- 525 to 412 +/- 126 ng/min (70 +/- 8%). Indomethacin or meclofenamate, prostaglandin synthesis inhibitors, did not affect the decrease in urinary sodium excretion but attenuated the increase in renin secretion rate, from 1,523 +/- 416 to 866 +/- 413 ng/min (51 +/- 18%). Addition of metoprolol to indomethacin-pretreated dogs attenuated the increase in renin secretion rate from 833 +/- 327 to 94 +/- 60 ng/min (86 +/- 10%). These results indicate that reflex RNS at constant renal perfusion pressure results in an increase in renin secretion rate that is largely mediated by renal beta 1-adrenoceptors and is partly dependent on intact renal prostaglandin synthesis. The beta 1-adrenoceptor-mediated increase in renin secretion rate is independent of and not in series with renal prostaglandins.

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Role of Renal Perfusion Pressure Versus Angiotensin II on Renal Oxidative Stress in Angiotensin II–Induced Hypertensive Rats

Hypertension ◽

10.1161/hypertensionaha.110.151332 ◽

2010 ◽

Vol 55 (6) ◽

pp. 1425-1430 ◽

Cited By ~ 22

Author(s):

Aaron J. Polichnowski ◽

Chunhua Jin ◽

Chun Yang ◽

Allen W. Cowley

Keyword(s):

Oxidative Stress ◽

Angiotensin Ii ◽

Perfusion Pressure ◽

Renal Perfusion ◽

Hypertensive Rats ◽

Renal Perfusion Pressure

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Role of renal interstitial hydrostatic pressure in the pressure diuresis response

AJP Renal Physiology ◽

10.1152/ajprenal.1989.256.1.f63 ◽

1989 ◽

Vol 256 (1) ◽

pp. F63-F70 ◽

Cited By ~ 19

Author(s):

J. Garcia-Estan ◽

R. J. Roman

Keyword(s):

Hydrostatic Pressure ◽

Sodium Excretion ◽

Perfusion Pressure ◽

Renal Perfusion ◽

Renal Capsule ◽

Interstitial Pressure ◽

Renal Perfusion Pressure ◽

Residual Response

The present study examines the role of renal interstitial hydrostatic pressure (RIHP) in the pressure-diuretic and -natriuretic response. The relationships between RIHP, sodium excretion, and renal perfusion pressure (RPP) were determined in antidiuretic and volume-expanded (VE) rats with an intact or decapsulated kidney. RIHP was measured by use of the implanted capsule technique. RIHP increased significantly from 7.5 +/- 0.8 to 12.0 +/- 1.4 mmHg in VE animals and from 3.3 +/- 0.4 to 5.2 +/- 0.7 mmHg in antidiuretic rats after RPP was varied from 100 to 150 mmHg. The pressure-natriuretic response of the antidiuretic rats was blunted compared with that observed in the VE rats. Decapsulation of the kidney in VE rats lowered RIHP and reduced, but did not eliminate, the pressure-natriuretic response. To determine whether this residual response was related to changes in interstitial pressure in the medulla, cortical (CIHP) and medullary interstitial hydrostatic pressures (MIHP) were simultaneously measured in VE rats with an intact or decapsulated kidney. In control rats CIHP and MIHP were similar at all levels of RPP studied. In rats with the renal capsule removed MIHP was higher than CIHP and rose significantly from 6.7 +/- 0.8 to 9.2 +/- 0.8 mmHg when RPP was varied from 100 to 150 mmHg. These results indicate that pressure diuresis and natriuresis is accompanied by changes in RIHP and the response is modulated by the basal level of RIHP. These findings suggest that changes in MIHP may serve as an intrarenal signal for this response.

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Purinergic P2X1 receptor, purinergic P2X7 receptor, and angiotensin II type 1 receptor interactions in the regulation of renal afferent arterioles in angiotensin II-dependent hypertension

AJP Renal Physiology ◽

10.1152/ajprenal.00602.2019 ◽

2020 ◽

Vol 318 (6) ◽

pp. F1400-F1408 ◽

Cited By ~ 1

Author(s):

Supaporn Kulthinee ◽

Weijian Shao ◽

Martha Franco ◽

L. Gabriel Navar

Keyword(s):

Angiotensin Ii ◽

Perfusion Pressure ◽

Renal Perfusion ◽

Ang Ii ◽

Renal Perfusion Pressure ◽

Arteriolar Resistance ◽

Purinergic P2x7 Receptor ◽

Afferent Arterioles ◽

Purinergic P2x Receptors

In ANG II-dependent hypertension, ANG II activates ANG II type 1 receptors (AT1Rs), elevating blood pressure and increasing renal afferent arteriolar resistance (AAR). The increased arterial pressure augments interstitial ATP concentrations activating purinergic P2X receptors (P2XRs) also increasing AAR. Interestingly, P2X1R and P2X7R inhibition reduces AAR to the normal range, raising the conundrum regarding the apparent disappearance of AT1R influence. To evaluate the interactions between P2XRs and AT1Rs in mediating the increased AAR elicited by chronic ANG II infusions, experiments using the isolated blood perfused juxtamedullary nephron preparation allowed visualization of afferent arteriolar diameters (AAD). Normotensive and ANG II-infused hypertensive rats showed AAD responses to increases in renal perfusion pressure from 100 to 140 mmHg by decreasing AAD by 26 ± 10% and 19 ± 4%. Superfusion with the inhibitor P2X1Ri (NF4490; 1 μM) increased AAD. In normotensive kidneys, superfusion with ANG II (1 nM) decreased AAD by 16 ± 4% and decreased further by 19 ± 5% with an increase in renal perfusion pressure. Treatment with P2X1Ri increased AAD by 30 ± 6% to values higher than those at 100 mmHg plus ANG II. In hypertensive kidneys, the inhibitor AT1Ri (SML1394; 1 μM) increased AAD by 10 ± 7%. In contrast, treatment with P2X1Ri increased AAD by 21 ± 14%; combination with P2X1Ri plus P2X7Ri (A438079; 1 μM) increased AAD further by 25 ± 8%. The results indicate that P2X1R, P2X7R, and AT1R actions converge at receptor or postreceptor signaling pathways, but P2XR exerts a dominant influence abrogating the actions of AT1Rs on AAR in ANG II-dependent hypertension.

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Atrial appendectomy reduces ANF but not sodium excretion in acute vasopressin hypertension

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1990.258.1.r77 ◽

1990 ◽

Vol 258 (1) ◽

pp. R77-R81

Author(s):

R. S. Zimmerman ◽

R. W. Barbee ◽

A. Martinez ◽

A. A. MacPhee ◽

N. C. Trippodo

Keyword(s):

Glomerular Filtration Rate ◽

Glomerular Filtration ◽

Sodium Excretion ◽

Filtration Rate ◽

Perfusion Pressure ◽

Renal Perfusion ◽

Sprague Dawley ◽

Renal Perfusion Pressure ◽

Sprague Dawley Rats ◽

Circulating Levels

The present study was designed to determine whether atrial appendectomy would decrease the sodium excretion associated with pressor doses of arginine vasopressin (AVP) infusion in rats by decreasing circulating levels of atrial natriuretic factor (ANF). Ten to 21 days after either sham (n = 9) or bilateral atrial appendectomy (n = 13) AVP (19 ng.kg-1.min-1) was infused for 90 min in anesthetized Sprague-Dawley rats. Atrial appendectomy decreased circulating ANF levels from 469 +/- 70 pg/ml in sham-operated animals to 259 +/- 50 pg/ml (P less than 0.05) in atrial-appendectomized animals after 90 min of AVP infusion. Despite a reduction in circulating levels of ANF, sodium excretion, potassium excretion, and urine flow increased and were not affected by bilateral atrial appendectomy. Glomerular filtration rate and mean arterial pressure significantly increased in both groups of rats. The present study supports non-ANF factors such as increases in renal perfusion pressure and/or glomerular filtration rate as potential mechanisms in AVP-induced natriuresis.

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