Reduced autoregulatory effectiveness in adenosine 1 receptor-deficient mice

2006 ◽  
Vol 290 (4) ◽  
pp. F888-F891 ◽  
Author(s):  
S. Hashimoto ◽  
Y. Huang ◽  
J. Briggs ◽  
J. Schnermann
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Blood Pressure Reduction ◽  
Renal Perfusion ◽  
Renal Vascular Resistance ◽  
Tubuloglomerular Feedback ◽  
Wild Type ◽  
Before And After ◽  
Renal Vascular ◽  
Deficient Mice

Adjustments of renal vascular resistance in response to changes in blood pressure are mediated by an interplay between the myocyte-inherent myogenic and the kidney-specific tubuloglomerular feedback (TGF) mechanisms. Using mice with deletion of the A1 adenosine receptor (A1AR) gene, we tested the prediction that the absence of TGF, previously established to result from A1AR deficiency, is associated with a reduction in the efficiency of autoregulation. In anesthetized wild-type (A1AR+/+) and A1AR-deficient mice (A1AR−/−), glomerular filtration rate (GFR) and renal blood flow (RBF) were determined before and after reducing renal perfusion pressure through a suprarenal aortic clamp. In response to a blood pressure reduction by 15.9 ± 1.34 mmHg in A1AR−/− ( n = 9) and by 14.2 ± 0.9 mmHg in A1AR+/+ mice ( n = 8; P = 0.31), GFR fell by 187.9 ± 37 μl/min and by 72.3 ± 10 μl/min in A1AR−/− and A1AR+/+ mice, respectively ( P = 0.013). Similarly, with pressure reductions of 14.8 ± 1.1 and 13.3 ± 1.5 mmHg in A1AR−/− ( n = 9) and wild-type mice ( n = 8), respectively ( P = 0.43), RBF fell by 0.17 ± 0.02 ml/min in A1AR−/− mice and by only 0.08 ± 0.02 ml/min in wild-type animals ( P = 0.0039). Autoregulatory indexes for both GFR and RBF were significantly higher in A1AR−/− compared with A1AR+/+ mice, indicating reduced regulatory responsiveness in the knockout animals. We conclude that autoregulation of renal vascular resistance is less complete in A1AR-deficient mice, an effect that is presumably related to absence of TGF regulation in these animals.

scholarly journals Angiotensin II blockade causes acute renal failure in eNOS-deficient mice

2001 ◽  
Vol 2 (1_suppl) ◽  
pp. S199-S203 ◽  
Author(s):  
Jürgen Schnermann ◽  
Yuning G Huang ◽  
Josie P Briggs
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Glomerular Filtration ◽  
Vascular Resistance ◽  
Knockout Mice ◽  
Renal Vascular Resistance ◽  
Wild Type ◽  
Arteriolar Tone ◽  
Renal Vascular ◽  
Deficient Mice

Compared with wild-type mice, adult endothelial nitric oxide synthase (eNOS) knockout mice (eight months of age) have increased blood pressure (BP) (126±9 mmHg vs. 100±4 mmHg), and an increased renal vascular resistance (155±16 vs. 65±4 mmHg.min/ml). Renal vascular resistance responses to i.v. administration of noradrenaline were markedly enhanced in eNOS knockout mice. Glomerular filtration rate (GFR) of anaesthetised eNOS -/- mice was 324±57 µl/min gKW, significantly lower than the GFR of 761±126 µl/min.gKW in wild-type mice. AT1-receptor blockade with i.v. candesartan (1—1.5 mg/kg) reduced arterial blood pressure and renal vascular resistance, and increased renal blood flow (RBF) to about the same extent in wild-type and eNOS -/- mice. Candesartan did not alter GFR in wild-type mice (761±126 vs. 720±95 µl/min.gKW), but caused a marked decrease in GFR in eNOS -/- mice (324.5±75.2 vs. 77±18 µl/min.gKW). A similar reduction in GFR of eNOS deficient mice was also caused by angiotensin-converting enzyme (ACE) inhibition. Afferent arteriolar granularity, a measure of renal renin expression, was found to be reduced in eNOS -/- compared with wild-type mice. In chronically eNOS-deficient mice, angiotensin II (Ang II) is critical for maintaining glomerular filtration pressure and GFR, presumably through its effect on efferent arteriolar tone.

Inhibition of ROMK blocks macula densa tubuloglomerular feedback yet causes renal vasoconstriction in anesthetized rats

2017 ◽  
Vol 312 (6) ◽  
pp. F1120-F1127 ◽  
Author(s):  
Magali Araujo ◽  
William J. Welch ◽  
Xiaoyan Zhou ◽  
Kathleen Sullivan ◽  
Shawn Walsh ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Renal Vascular Resistance ◽  
Tubuloglomerular Feedback ◽  
Volume Depletion ◽  
Renal Vasoconstriction ◽  
Compound C ◽  
Altered Blood ◽  
Renal Vascular ◽  
Dose Dependent

The Na+-K+-2Cl− cotransporter (NKCC2) on the loop of Henle is the site of action of furosemide. Because outer medullary potassium channel (ROMK) inhibitors prevent reabsorption by NKCC2, we tested the hypothesis that ROMK inhibition with a novel selective ROMK inhibitor (compound C) blocks tubuloglomerular feedback (TGF) and reduces vascular resistance. Loop perfusion of either ROMK inhibitor or furosemide caused dose-dependent blunting of TGF, but the response to furosemide was 10-fold more sensitive (IC50 = 10−6 M for furosemide and IC50 = 10−5 M for compound C). During systemic infusion, both diuretics inhibited TGF, but ROMK inhibitor was 10-fold more sensitive (compound C: 63% inhibition; furosemide: 32% inhibition). Despite blockade of TGF, 1 h of constant systemic infusion of both diuretics reduced the glomerular filtration rate (GFR) and renal blood flow (RBF) by 40–60% and increased renal vascular resistance (RVR) by 100–200%. Neither diuretic altered blood pressure or hematocrit. Proximal tubule hydrostatic pressures (PPT) increased transiently with both diuretics (compound C: 56% increase; furosemide: 70% increase) but returned to baseline. ROMK inhibitor caused more natriuresis (3,400 vs. 1,600% increase) and calciuresis (1,200 vs. 800% increase) but less kaliuresis (33 vs. 167% increase) than furosemide. In conclusion, blockade of ROMK or Na+-K+-2Cl− transport inhibits TGF yet increases renal vascular resistance. The renal vasoconstriction was independent of volume depletion, blood pressure, TGF, or PPT.

Determinants of renal vasoconstriction after systemic inhibition of nitric oxide synthesis in rats

1996 ◽  
Vol 270 (6) ◽  
pp. R1203-R1207
Author(s):  
E. Brand-Schieber ◽  
M. Pucci ◽  
A. Nasjletti
Keyword(s):  
Nitric Oxide ◽  
Vascular Resistance ◽  
Perfusion Pressure ◽  
Renal Perfusion ◽  
Renal Vascular Resistance ◽  
Tubuloglomerular Feedback ◽  
Nitric Oxide Synthesis ◽  
Renal Vasoconstriction ◽  
Renal Perfusion Pressure ◽  
Renal Vascular

The effects of NG-nitro-L-arginine (L-NNA, 10 mg/kg i.v.) on renal hemodynamics were examined in control rats, rats in which renal perfusion pressure was prevented from rising after L-NNA by constricting the abdominal aorta, and rats in which tubuloglomerular feedback was inhibited by furosemide pretreatment, ureteral ligation, or both interventions combined. In control rats, L-NNA increased (P < 0.05) renal vascular resistance (274 +/- 27%) along with systemic arterial (54 +/- 4%) and renal perfusion (54 +/- 5%) pressures and decreased (P < 0.05) renal blood flow (57 +/- 4%). In rats in which renal perfusion pressure was prevented from increasing along with systemic arterial pressure (54 +/- 4%), the L-NNA-induced elevation of renal vascular resistance (173 +/- 27%) was less intense (P < 0.05). In another study, where renal perfusion pressure was fixed at pre-L-NNA levels, L-NNA-induced increases in renal vascular resistance (130 +/- 20%) were attenuated (P < 0.05) further with furosemide pretreatment (52 +/- 12%), with ureteral ligation (75 +/- 10%), and with furosemide pretreatment and ureteral ligation combined (32 +/- 8%). These data suggest that vasoconstrictor mechanisms linked to tubuloglomerular feedback and perfusion pressure elevation contribute to renal vasoconstriction after systemic inhibition of nitric oxide synthesis with L-NNA.

Limb tourniquet and intramuscular clostridial toxin effects on renal function

1962 ◽  
Vol 17 (1) ◽  
pp. 83-86 ◽  
Author(s):  
James F. Nickel ◽  
John A. Gagnon ◽  
Leonard Levine
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Sodium Excretion ◽  
Renal Vascular Resistance ◽  
Arterial Blood ◽  
Hind Limbs ◽  
Renal Changes ◽  
Anesthetized Dogs ◽  
Peripheral Trauma ◽  
Renal Vascular

Eight anesthetized dogs, given Clostridium perfringens type A toxic filtrate into the hind-limb muscles, showed severe spreading edema, hemoconcentration, marked reduction in para-aminohippurate (PAH) and creatinine clearances, and a rise in the renal vascular resistance. In the first 4 hr sodium excretion fell sharply, and mean arterial blood pressure, slightly. In eight similar dogs venous-occlusive pneumatic tourniquets were applied high on both hind limbs for 90 min. Edema was localized and minimal. Hematocrit was unchanged. PAH and creatinine clearances were extremely low in the second 30-min period of the occlusion but had risen somewhat in the last 30-min period. Sodium excretion was greatly reduced. Arterial pressure and vascular resistance rose very significantly. Upon removal of the tourniquets, PAH and creatinine clearances, blood pressure, and renal vascular resistance returned toward normal. Sodium excretion continued to fall. In many respects the renal changes resulting from two different forms of peripheral trauma are similar. Submitted on August 14, 1959

Renal vasodilatation after inhibition of renin or converting enzyme in marmoset

1986 ◽  
Vol 251 (5) ◽  
pp. H897-H902
Author(s):  
D. Neisius ◽  
J. M. Wood ◽  
K. G. Hofbauer
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Angiotensin Ii ◽  
Renal Blood Flow ◽  
Vascular Resistance ◽  
Enzyme Inhibitor ◽  
Renal Vascular Resistance ◽  
Converting Enzyme ◽  
Renin Inhibition ◽  
Renal Vascular

The relative importance of angiotensin II for the renal vasodilatory response after converting-enzyme inhibition was evaluated by a comparison of the effects of converting-enzyme and renin inhibition on renal vascular resistance. Renal, mesenteric, and hindquarter blood flows were measured with chronically implanted ultrasonic-pulsed Doppler flow probes in conscious, mildly volume-depleted marmosets after administration of a converting-enzyme inhibitor (enalaprilat, 2 mg/kg iv), a synthetic renin inhibitor (CGP 29,287, 1 mg/kg iv), or a renin-inhibitory monoclonal antibody (R-3-36-16, 0.1 mg/kg iv). Enalaprilat reduced blood pressure (-16 +/- 4 mmHg, n = 6) and induced a selective increase in renal blood flow (27 +/- 8%, n = 6). CGP 29,287 and R-3-36-16 induced comparable reductions in blood pressure (-16 +/- 4 mmHg, n = 6 and -20 +/- 4 mmHg, n = 5, respectively) and selective increases in renal blood flow (36 +/- 12%, n = 6 and 34 +/- 16%, n = 4, respectively). The decrease in renal vascular resistance was of similar magnitude for all of the inhibitors (enalaprilat -28 +/- 3%, CGP 29,287 -32 +/- 6%; and R-3-36-16 -33 +/- 7%). These results indicate that the renal vasodilatation induced after converting-enzyme or renin inhibition is mainly due to decreased formation of angiotensin II.

Effects of renal perfusion pressure on the natriuresis induced by atrial natriuretic factor

1987 ◽  
Vol 253 (2) ◽  
pp. F234-F238
Author(s):  
A. A. Seymour ◽  
S. G. Smith ◽  
E. K. Mazack
Keyword(s):  
Vascular Resistance ◽  
Atrial Natriuretic Factor ◽  
Perfusion Pressure ◽  
Renal Perfusion ◽  
Renal Vascular Resistance ◽  
Base Line ◽  
Renal Perfusion Pressure ◽  
Natriuretic Factor ◽  
Renal Vascular ◽  
Atrial Natriuretic

Synthetic atrial natriuretic factor (ANF 101-126) was infused at 1, 5, 25, and 125 pmol X kg-1 X min-1 into the renal artery of anesthetized, one-kidney dogs. During administration of 25 and 125 pmol X kg-1 X min-1 of ANF 101-126, fractional sodium excretion (FENa) rose from 1.4 +/- 0.3 to 6.6 +/- 1.1 and 5.6 +/- 1.3% when renal perfusion pressure (RPP) was at its basal level (112 +/- 5 mmHg). When base-line RPP was lowered to 101 +/- 5 mmHg by tightening a suprarenal aortic constriction, the same doses raised FENa to only 5.6 +/- 1.6 and 5.1 +/- 1.6%. A larger reduction of beginning RPP to 82 +/- 4 mmHg suppressed the natriuretic responses to 25 and 125 pmol X kg-1 X min-1 of ANF 101-126 to only 1.4 +/- 0.8 and 0.8 +/- 0.3%, respectively.During the peak natriuretic dose of 25 pmol X kg-1 X min-1, renal vascular resistance (RVR) fell from 0.88 +/- 0.10 to 0.68 +/- 0.07, from 0.78 +/- 0.10 to 0.68 +/- 0.12, and from 0.60 +/- 0.06 to 0.61 +/- 0.06 mmHg X ml-1 X min-1 at RPP = RPP = 112, 101, and 82 mmHg, respectively. ANF 101-126 did not affect glomerular filtration rate (GFR) at any level of RPP tested. In conclusion, the natriuretic responses to ANF 101-126 occurred without changes in GFR and were modulated by the prevailing levels of renal perfusion pressure and renal vascular resistance.

Differences in ouabain-induced natriuresis between isolated kidneys of Milan hypertensive and normotensive rats

1992 ◽  
Vol 82 (2) ◽  
pp. 185-190 ◽  
Author(s):  
Roland Foulkes ◽  
Romana G. Ferrario ◽  
Patricia Salvati ◽  
Giuseppe Bianchi
Keyword(s):  
Vascular Resistance ◽  
Receptor Occupancy ◽  
Renal Vascular Resistance ◽  
The Other ◽  
Hypertensive Rats ◽  
Other Hand ◽  
Before And After ◽  
Renal Vascular ◽  
Isolated Kidneys

1. Several observations support the hypothesis that in rats of the Milan hypertensive strain elevated levels of a circulating ouabain-like factor might normalize the elevated Na+ reabsorption, but, on the other hand, might contribute to the development of hypertension. 2. As the receptor occupancy of this endogenous factor seems to be reversible, the aim of our study was to test, in vitro, the hypothesis of its presence in isolated kidneys from Milan hypertensive rats by studying the response to exogenous ouabain before and after prolonged washing. 3. The kidneys were isolated from adult Milan hypertensive rats and from age-matched normotensive controls and ouabain was given at two different experimental time intervals: shortly (15 min) after washout or after a further 60 min of washout (75 min in total). Comparative experiments with the diuretic hydrochlorothiazide were performed using the same protocol. 4. Ouabain given after 15 min of perfusion caused an increase in renal vascular resistance, diuresis and natriuresis; these haemodynamic and tubular responses were similar in kidneys from both Milan hypertensive and Milan normotensive rats. If given after the washout period, ouabain caused a comparable increase in renal vascular resistance, but a significantly greater natriuresis in kidneys from Milan hypertensive rats as compared with kidneys from Milan normotensive rats. On the other hand, hydrochlorothiazide caused similar natriuresis in kidneys from both strains after washout. 5. These results support the hypothesis that a factor, capable of interacting with the ouabain receptor on the Na+/K+−ATPase of tubular cells, is present in the kidney of adult Milan hypertensive rats and that it can be removed by prolonged washout.

Abnormal Renal Haemodynamics and Renin Suppression in Hypertensive Patients

1970 ◽  
Vol 38 (1) ◽  
pp. 101-110 ◽  
Author(s):  
M. A. D. H. Schalekamp ◽  
M. P. A. Schalekamp-Kuyken ◽  
W. H. Birkenhäger
Keyword(s):  
Blood Pressure ◽  
Vascular Resistance ◽  
Renal Plasma Flow ◽  
Plasma Renin ◽  
Renal Vascular Resistance ◽  
Hypertensive Disease ◽  
Filtration Fraction ◽  
Plasma Renin Concentration ◽  
Renal Vascular ◽  
Intravascular Pressure

1. Intra-arterial pressure, renal plasma flow and glomerular filtration rate were estimated in thirty-two patients with benign essential hypertension. In twenty cases plasma renin concentrations were also determined. Variability of blood pressure was estimated by automatic indirect pressure recording. 2. There was an even distribution between high and low values of renal vascular resistance and filtration fraction. Variability of blood pressure was inversely related to renal vascular resistance. 3. In five patients plasma renin concentration was found to be abnormally low both in the recumbent and in the 45° tilt position. 4. Plasma renin concentration was related to renal blood flow, renal vascular resistance, filtration fraction and variability of blood pressure. 5. The results suggest that in hypertension renin release is suppressed by an increase in intravascular pressure at the level of the juxtaglomerularcells. The extent of renin suppression seems to be related to the stage of hypertensive disease.

Sign in / Sign up

Export Citation Format

Share Document