Renal Blood Flow

Hura, Claudia; Stein, Janice Gross

doi:10.1002/cphy.cp080125

Cited by 13 publications

(17 citation statements)

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“…First, PC MRI measurements of RBF were performed in the right renal artery only and assumed equal perfusion of both kidneys. However, this can be justified since kidney perfusion should amount to ≈20% of CO in healthy individuals and we measured a baseline RBF of 19±4.4% of CO. Secondly, we studied healthy volunteers and this limits the generalizability of our findings to CKD patients. Further studies in kidney disease require validation of the combined BOLD and PC MRI measurements.…”

Section: Discussionmentioning

confidence: 99%

“…After correction for background phase‐offset errors and aliasing, mean RBF (mL/s) was calculated in the right proximal renal artery using manual vessel segmentation in each cardiac phase (Figure D through F). Further RBF analysis assumed equal perfusion of both right and left kidneys . To make direct comparison between the radioisotope ERPF‐ and MRI‐derived RBF measurements possible, MR RBF was corrected for body surface area (according to Haycock) and hematocrit (Ht) to calculate a PC MRI‐based renal plasma flow (PC‐RPF).…”

Section: Methodsmentioning

confidence: 99%

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Magnetic Resonance Imaging–Derived Renal Oxygenation and Perfusion During Continuous, Steady‐State Angiotensin‐II Infusion in Healthy Humans

Bel

Coolen

Nederveen

et al. 2016

JAHA

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BackgroundThe role of kidney hypoxia is considered pivotal in the progression of chronic kidney disease. A widely used method to assess kidney oxygenation is blood oxygen level dependent (BOLD)–magnetic resonance imaging (MRI), but its interpretation remains problematic. The BOLD‐MRI signal is the result of kidney oxygen consumption (a proxy of glomerular filtration) and supply (ie, glomerular perfusion). Therefore, we hypothesized that with pharmacological modulation of kidney blood flow, renal oxygenation, as assessed by BOLD‐MRI, correlates to filtration fraction (ie, glomerular filtration rate/effective renal plasma flow) in healthy humans.Methods and ResultsEight healthy volunteers were subjected to continuous angiotensin‐II infusion at 0.3, 0.9, and 3.0 ng/kg per minute. At each dose, renal oxygenation and blood flow were assessed using BOLD and phase‐contrast MRI. Subsequently, “gold standard” glomerular filtration rate/effective renal plasma flow measurements were performed under the same conditions. Renal plasma flow decreased dose dependently from 660±146 to 467±103 mL/min per 1.73 m2 (F[3, 21]=33.3, P<0.001). Glomerular filtration rate decreased from 121±23 to 110±18 mL/min per 1.73 m2 (F[1.8, 2.4]=6.4, P=0.013). Cortical transverse relaxation rate (R2*; increases in R2* represent decreases in oxygenation) increased by 7.2±3.8% (F[3, 21]=7.37, P=0.001); medullar R2* did not change. Cortical R2* related to filtration fraction (R 2 0.46, P<0.001).ConclusionsBy direct comparison between “gold standard” kidney function measurements and BOLD MRI, we showed that cortical oxygenation measured by BOLD MRI relates poorly to glomerular filtration rate but is associated with filtration fraction. For future studies, there may be a need to include renal plasma flow measurements when employing renal BOLD‐MRI.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Magnetic Resonance Imaging–Derived Renal Oxygenation and Perfusion During Continuous, Steady‐State Angiotensin‐II Infusion in Healthy Humans

Bel

Coolen

Nederveen

et al. 2016

JAHA

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“…22 In this setting, there is also an increased renal prostaglandin release that may counteract the effects of vasoconstrictors in the renal circulation, because the inhibition of prostaglandin synthesis accentuates renal vasoconstriction in these experimental models. 22 Therefore, it can be suggested that the activation of vasoconstrictor systems in the setting of gastrointestinal bleeding in humans may be more harmful to the cirrhotic kidneys compared with the normal kidneys be- Abbreviations: NSAIDs, nonsteroidal anti-inflammatory drugs; GIB, gastrointestinal bleeding.…”

Section: Discussionmentioning

confidence: 99%

Renal failure after upper gastrointestinal bleeding in cirrhosis: Incidence, clinical course, predictive factors, and short-term prognosis

Cárdenas

2001

Hepatology

276

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Patients with advanced cirrhosis commonly develop disturbances in renal function, such as sodium retention, water retention, and renal failure. 1-4 Among them, renal failure is the most relevant in clinical practice, because its appearance usually entails a very poor prognosis. 1-4 Several factors predisposing to the development of renal failure in patients with cirrhosis have been identified, including spontaneous bacterial peritonitis, large-volume paracentesis without intravenous administration of albumin, and treatment with several drugs, such as nonsteroidal anti-inflammatory drugs or aminoglycosides. [3][4][5] Despite the high frequency and clinical importance of gastrointestinal bleeding in cirrhosis, no studies have so far been reported aimed at specifically assessing the relationship between bleeding and renal failure in patients with cirrhosis. Several factors related with gastrointestinal bleeding may have a deleterious effect on kidney function. First, the reduced intravascular volume caused by the blood loss may cause renal hypoperfusion and lead to a reduction in glomerular filtration rate. Second, renal function may also be adversely affected by bacterial infections, which develop frequently in the setting of gastrointestinal bleeding. 5,6 Finally, it has been proposed that small losses of blood volume not sufficient by themselves to cause a reduction in renal perfusion in patients without liver disease would aggravate the already-reduced effective arterial blood volume present in advanced cirrhosis and trigger the development of hepatorenal syndrome. 7 The current study was undertaken to assess the incidence, clinical course, predictive factors, and short-term prognosis of renal failure after gastrointestinal bleeding in a large series of consecutive patients with cirrhosis seen in a specialized gastrointestinal unit of a tertiary referral center. Moreover, to investigate whether cirrhosis per se is a predisposing factor for the development of renal failure after gastrointestinal bleeding, the incidence of renal failure in patients with cirrhosis was compared with that of a group of noncirrhotic patients matched by age and intensity of the bleeding episode. PATIENTS AND METHODS Study PopulationThe clinical records of 192 consecutive episodes of upper-gastrointestinal bleeding in 178 patients with cirrhosis admitted to the liver unit of Hospital Clínic of Barcelona during a 2-year period were reviewed. Patients with a hospital stay or survival of less than 48 hours after bleeding (8 and 9 patients, respectively) were excluded from the analysis. Therefore, the study was performed in a total of 175 episodes of upper-gastrointestinal bleeding in 161 patients. Of them, 104 patients were receiving diuretics before admisssion, and 21 patients were receiving ␤-blockers (10 of these latter patients were treated with a combination of ␤-blockers and nitrates).Abbreviations: PRBC, packed red blood cell; ATN, acute tubular necrosis.

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“…At relatively high concentrations, Ang 1-7 and Ang IV exert modest renal vasodilation and natriuresis [967,[1060][1061][1062] . Although the putative receptors have not been cloned, recent studies indicate that the Ang [1][2][3][4][5][6][7] receptor is encoded by the MAS protooncogene [1068] . Although the putative receptors have not been cloned, recent studies indicate that the Ang [1][2][3][4][5][6][7] receptor is encoded by the MAS protooncogene [1068] .…”

Section: Intrarenal Angiotensin Receptorsmentioning

confidence: 99%

The Renal Microcirculation

et al. 2008

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Renal Blood Flow

Abstract: The sections in this article are: Measurement of Renal Blood Flow Total Renal Blood Flow Regional Cortical Blood Flow Medullary Blood Flow Renal Microcirculation Control of Renal Circulation Intrinsic Factors Extrinsic Control … Show more

Cited by 13 publications

References 534 publications

Magnetic Resonance Imaging–Derived Renal Oxygenation and Perfusion During Continuous, Steady‐State Angiotensin‐II Infusion in Healthy Humans

Magnetic Resonance Imaging–Derived Renal Oxygenation and Perfusion During Continuous, Steady‐State Angiotensin‐II Infusion in Healthy Humans

Renal failure after upper gastrointestinal bleeding in cirrhosis: Incidence, clinical course, predictive factors, and short-term prognosis

The Renal Microcirculation

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