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Hypertension Research : Official... Aug 2022Elevated arterial pulsatility is a common risk factor for cerebrovascular disease and chronic kidney disease (CKD), which suggests that the brain and kidneys may have...
Elevated arterial pulsatility is a common risk factor for cerebrovascular disease and chronic kidney disease (CKD), which suggests that the brain and kidneys may have similar hemodynamic profiles. The objectives of this study were twofold: 1) to compare and contrast the cerebral and renal blood flow parameters in adults without CKD (hereafter, non-CKD adults) and CKD patients and 2) to determine the common predictor(s) of cerebral and renal hemodynamics among pressure pulsatility and several cardiovascular risk factors. In 110 non-CKD adults and 66 CKD patients, cerebral and renal blood flow velocity (BFV) were measured by transcranial Doppler and Duplex ultrasonography, respectively. Pulsatile hemodynamics were assessed by the pulsatility (PI) and resistive (RI) indices. Aortic pulse pressure was measured by tonometry. Compared with non-CKD adults, CKD patients showed greater pulsatility of the BFV (i.e., systolic minus diastolic BFV), PI, and RI in the kidneys but not the brain. However, the cerebral and renal PI and RI values were strongly correlated in both non-CKD adults (both PI and RI values: r = 0.695) and CKD patients (both PI and RI values: r = 0.640) (all P < 0.001). Multiple linear regression analysis further demonstrated that the cerebral and renal PI and RI associations remained significant after adjustment for potential covariates (e.g., age, sex, the presence of CKD). The aortic pulse pressure was a significant predictor for both cerebral and renal PI and RI values. Collectively, our findings suggest that CKD patients have higher renal flow pulsatility, which is strongly and independently associated with cerebral flow pulsatility and aortic hemodynamics.
Topics: Adult; Blood Flow Velocity; Hemodynamics; Humans; Kidney; Renal Circulation; Renal Insufficiency, Chronic
PubMed: 35665784
DOI: 10.1038/s41440-022-00944-x -
Birth Defects Research Oct 2017The developing kidney is sensitive to both morphological and functional disturbances during the gestational and postnatal phases of growth and differentiation. Exposure... (Review)
Review
The developing kidney is sensitive to both morphological and functional disturbances during the gestational and postnatal phases of growth and differentiation. Exposure to drugs or chemicals during these critical windows of renal development can result in aplasia, dysplasia, polycystic kidney disease, hydronephrosis, or other features characteristic of nephrotoxicity, including tubule dilation, necrosis, or mineralization. Functional effects can occur without associated morphological abnormalities. Differences in the timing of nephrogenesis and morphologic renal development among species help to explain specific phenotypes of various gestational and postnatal teratogens and nephrotoxins. Functional maturation follows anatomical maturation, but important differences in maximally achieved glomerular filtration rate, concentrating ability and acid-base equilibrium between species makes comparison of these timings critical for accurate and consistent translation of laboratory animal toxicity data to the human clinical experience. Species and age dependent differences in the maturation of kidney transporters, renal xenobiotic metabolism and renal blood flow can have a profound effect on the toxicity profiles of agents and marked differences in the tolerability based on age. Advances in the understanding of the genetics of inherited renal diseases and the underlying cellular and molecular pathogenesis of renal developmental anomalies has helped provide mechanistic understanding of many teratogenic and perinatal nephrotoxic agents. Investigative studies have provided important translational and mechanistic information for assessing human pediatric nephrotoxic potential. Birth Defects Research 109:1243-1256, 2017. © 2017 Wiley Periodicals, Inc.
Topics: Acid-Base Equilibrium; Animals; Carcinogenesis; Female; Glomerular Filtration Rate; Humans; Kidney; Kidney Diseases; Pregnancy; Renal Circulation; Species Specificity; Teratogenesis; Teratogens; Xenobiotics
PubMed: 28766875
DOI: 10.1002/bdr2.1088 -
The Veterinary Clinics of North... Apr 2022Regulation of renal blood flow is by both extrinsic and intrinsic systems. Intrinsic regulation occurs via the afferent and efferent arterioles and tubuloglomerular... (Review)
Review
Regulation of renal blood flow is by both extrinsic and intrinsic systems. Intrinsic regulation occurs via the afferent and efferent arterioles and tubuloglomerular feedback mechanisms with activation of the juxtaglomerular apparatus. Mechanisms of acute kidney injury are frequently associated with changes in renal blood flow. Acute tubular necrosis and apoptosis are common in horses following ischemic or toxic insults and in sepsis-associated acute kidney injury. Sepsis-associated renal injury often has a complex mechanism of disease involving both functional and obstructive changes in intrarenal circulation. Acute interstitial nephritis may occur following Leptospira sp infection or can be secondary to tubular necrosis.
Topics: Acute Kidney Injury; Animals; Horse Diseases; Horses; Kidney; Nephritis, Interstitial; Renal Circulation
PubMed: 35282956
DOI: 10.1016/j.cveq.2021.11.001 -
Autonomic Neuroscience : Basic &... May 2017Thermal stress is a profound sympathetic stress in humans; kidney responses involve altered renal sympathetic nerve activity (RSNA), renal blood flow, and renal... (Review)
Review
Thermal stress is a profound sympathetic stress in humans; kidney responses involve altered renal sympathetic nerve activity (RSNA), renal blood flow, and renal epithelial transport. During mild cold stress, RSNA spectral power but not total activity is altered, renal blood flow is maintained or decreased, and epithelial transport is altered consistent with a sympathetic stress coupled with central volume loaded state. Hypothermia decreases RSNA, renal blood flow, and epithelial transport. During mild heat stress, RSNA is increased, renal blood flow is decreased, and epithelial transport is increased consistent with a sympathetic stress coupled with a central volume unloaded state. Hyperthermia extends these directional changes, until heat illness results. Because kidney responses are very difficult to study in humans in vivo, this review describes and qualitatively evaluates an in vivo human skin model of sympathetically regulated epithelial tissue compared to that of the nephron. This model utilizes skin responses to thermal stress, involving 1) increased skin sympathetic nerve activity (SSNA), decreased skin blood flow, and suppressed eccrine epithelial transport during cold stress; and 2) increased SSNA, skin blood flow, and eccrine epithelial transport during heat stress. This model appears to mimic aspects of the renal responses. Investigations of skin responses, which parallel certain renal responses, may aid understanding of epithelial-sympathetic nervous system interactions during cold and heat stress.
Topics: Animals; Biological Transport; Epithelium; Humans; Kidney; Models, Biological; Renal Circulation; Skin Physiological Phenomena; Stress, Physiological; Sympathetic Nervous System
PubMed: 28043810
DOI: 10.1016/j.autneu.2016.12.007 -
Current Opinion in Nephrology and... May 2015Over the past decade, a variety of MRI methods have been developed and applied to many kidney diseases. These MRI techniques show great promise, enabling the noninvasive... (Review)
Review
PURPOSE OF REVIEW
Over the past decade, a variety of MRI methods have been developed and applied to many kidney diseases. These MRI techniques show great promise, enabling the noninvasive assessment of renal structure, function and injury in individuals. This review will highlight the current applications of functional MRI techniques for the assessment of renal disease and discuss future directions.
RECENT FINDINGS
Many pathological (functional and structural) changes or factors in renal disease can be assessed by advanced MRI techniques. These include renal vascular structure and function (contrast-enhanced MRI, arterial spin labelling), tissue oxygenation (blood oxygen level dependent MRI), renal tissue injury and fibrosis (diffusion or magnetization transfer imaging, magnetic resonance elastography), renal metabolism (chemical exchange saturation transfer, spectroscopic imaging), nephron endowment (cationic-contrast imaging), sodium concentration (23Na-MRI) and molecular events (targeted-contrast imaging).
SUMMARY
Current advances in MRI techniques have enabled the noninvasive investigation of renal disease. Further development, evaluation and application of the MRI techniques should facilitate better understanding and assessment of renal disease, and the development of new imaging biomarkers, enabling the intensified treatment of high-risk populations and a more rapid interrogation of novel therapeutic agents and protocols.
Topics: Animals; Humans; Kidney; Kidney Diseases; Magnetic Resonance Imaging; Oxygen Consumption; Renal Circulation; Risk Assessment
PubMed: 26066472
DOI: 10.1097/MNH.0000000000000122 -
Physiological Reports Mar 2023The present study was to examine sex and strain differences in glomerular filtration rate (GFR) and renal blood flow (RBF) in C57BL6, 129/Sv, and C57BLKS/J mice, three...
The present study was to examine sex and strain differences in glomerular filtration rate (GFR) and renal blood flow (RBF) in C57BL6, 129/Sv, and C57BLKS/J mice, three commonly used mouse strains in renal research. GFR was measured by transdermal measurement of FITC-sinitrin clearance in conscious mice. RBF was measured by a flow probe placed in the renal artery under an anesthetic state. In C57BL6 mice, there were no sex differences in both GFR and RBF. In 129/Sv mice, females had significantly greater GFR than males at age of 24 weeks, but not at 8 weeks. However, males had higher RBF and lower renal vascular resistance (RVR). Similar to 129/Sv, female C57BLKS/J had significantly greater GFR at both 8 and 24 weeks, lower RBF, and higher RVR than males. Across strains, male 129/Sv had lower GFR and higher RBF than male C57BL6, but no significant difference in GFR and greater RBF than male C57BLKS/J. No significant difference in GFR or RBF was observed between C57BL6 and C57BLKS/J mice. Deletion of eNOS in C57BLKS/J mice reduced GFR in both sexes, but decreased RBF in males. Furthermore, there were no sex differences in the severity of renal injury in eNOS dbdb mice. Taken together, our study suggests that sex differences in renal hemodynamics in mice are strain and age dependent. eNOS was not involved in the sex differences in GFR, but in RBF. Furthermore, the sexual dimorphism did not impact the severity of renal injury in diabetic nephropathy.
Topics: Mice; Male; Animals; Female; Mice, Inbred C57BL; Kidney; Hemodynamics; Renal Circulation; Vascular Resistance; Glomerular Filtration Rate
PubMed: 36946063
DOI: 10.14814/phy2.15644 -
Hypertension (Dallas, Tex. : 1979) Feb 2020Impaired renal autoregulation permits more transmission of disturbance in systemic blood pressure, which initiates barotrauma in intrarenal microvasculatures such as...
Impaired renal autoregulation permits more transmission of disturbance in systemic blood pressure, which initiates barotrauma in intrarenal microvasculatures such as glomerular and tubulointerstitial capillaries, contributing to the development of kidney damage and deterioration in renal function, especially under the conditions with high blood pressure. Although it has been postulated that autoregulatory efficiency is attenuated in the aging kidney, direct evidence remains lacking. In the present study, we measured the autoregulation of renal blood flow, myogenic response of afferent arteriole (Af-Art), tubuloglomerular feedback in vivo with micropuncture, as well as tubuloglomerular feedback in vitro in isolated perfused juxtaglomerular apparatus in young and aged C57BL/6 mice. We found that renal blood flow was not significantly changed in response to a defined elevation of renal arterial pressure in young mice but significantly increased in aged mice. Additionally, myogenic response of Af-Art measured by microperfusion with a stepwise increase in perfusion pressure was significantly blunted in the aging kidney, which is associated with the attenuation of intraluminal pressure-induced intracellular calcium increases, as well as the reduced expression of integrin α5 (Itga5) in Af-Art. Moreover, both tubuloglomerular feedback in vivo and in vitro were nearly inactive in the aging kidney, which is associated with the significantly reduced expression of adenosine A1 receptor (A1AR) and suppressed vasoconstrictor response to adenosine in Af-Art. In conclusion, this study demonstrates that aging impairs renal autoregulation with blunted myogenic response and inhibited tubuloglomerular feedback response. The underlying mechanisms involve the downregulations of integrin α5 and A1AR in the Af-Art.
Topics: Aging; Animals; Blood Pressure; Disease Models, Animal; Glomerular Filtration Rate; Homeostasis; Hypertension; Kidney; Male; Mice; Mice, Inbred C57BL; Renal Circulation; Vasoconstriction
PubMed: 31838907
DOI: 10.1161/HYPERTENSIONAHA.119.13588 -
La Clinica Terapeutica 2020The aim of the present study was to demonstrate the relationship between hypertension stages according to JNC-8 classification and mean renal frame count (RFC), which is...
OBJECTIVE
The aim of the present study was to demonstrate the relationship between hypertension stages according to JNC-8 classification and mean renal frame count (RFC), which is an indicator of renal perfusion.
METHODS
In this retrospective study, 100 hypertensive patients without obstructive renal artery disease, who had been evaluated with renal artery angiography for hypertension, were allocated into 2 groups (Stage 1 and Stage 2 hypertension). During coronary angiography, the patients were evaluated by selective renal angiography using 6F Judkins catheter. Cineangiographic images were evaluated by the same clinician and mean RFC was estimated for both renal arteries. Injections during renal angiography were performed with power injector and same amount of radiopaque media with same speed was used for all patients.
RESULTS
There was no significant difference between the groups in terms of age, sex, duration of hypertension, and laboratory markers. Stage 2 hypertensive patients (Group 2) had a significantly higher mean RFC than Stage 1 hypertensive patients (Group 1) (p<0.001). The mean RFC of both kidneys in Group 2 was significantly higher than that of Group 1 (p<0.001 and p=0.023, respectively).
CONCLUSIONS
This study showed that the mean RFC increased with increases in hypertension levels and it could be used as an indicator of renal perfusion, which is an indirect marker of renal function. If renal artery flow gets slower, blood pressure levels increase and there is a proportional relationship between these two variables (mean RFC and blood pressure levels). This study also demonstrated that there was a statistically significant correlation between mean RFC and JNC-8 hypertension stages.
Topics: Aged; Contrast Media; Coronary Angiography; Female; Humans; Hypertension; Kidney; Kidney Function Tests; Male; Middle Aged; Renal Circulation; Retrospective Studies
PubMed: 32141485
DOI: 10.7417/CT.2020.2203 -
Seminars in Nephrology Nov 2019The kidneys receive approximately 20% of cardiac output and have a low fractional oxygen extraction. Quite paradoxically, however, the kidneys are highly susceptible to... (Review)
Review
The kidneys receive approximately 20% of cardiac output and have a low fractional oxygen extraction. Quite paradoxically, however, the kidneys are highly susceptible to ischemic injury (injury associated with inadequate blood supply), which is most evident in the renal medulla. The predominant proposal to explain this susceptibility has been a mismatch between oxygen supply and metabolic demand. It has been proposed that unlike the well-perfused renal cortex, the renal medulla normally operates just above the threshold for hypoxia and that further reductions in renal perfusion cause hypoxic injury in this metabolically active region. An alternative proposal is that the true cause of ischemic injury is not a simple mismatch between medullary metabolic demand and oxygen supply, but rather the susceptibility of the outer medulla to vascular congestion. The capillary plexus of the renal outer medullary region is especially prone to vascular congestion during periods of ischemia. It is the failure to restore the circulation to the outer medulla that mediates complete and prolonged ischemia to much of this region, leading to injury and tubular cell death. We suggest that greater emphasis on developing clinically useful methods to help prevent or reverse the congestion of the renal medullary vasculature may provide a means to reduce the incidence and cost of acute kidney injury.
Topics: Acute Kidney Injury; Animals; Humans; Ischemia; Kidney Cortex; Kidney Medulla; Oxygen Consumption; Prognosis; Regional Blood Flow; Renal Artery; Renal Circulation; Vasoconstriction
PubMed: 31836035
DOI: 10.1016/j.semnephrol.2019.10.002 -
Radiographics : a Review Publication of... 2016The kidneys and perinephric tissues can be affected by a variety of hematologic disorders, which usually occur in the setting of multisystem involvement. In many of... (Review)
Review
The kidneys and perinephric tissues can be affected by a variety of hematologic disorders, which usually occur in the setting of multisystem involvement. In many of these disorders, imaging is used to evaluate the extent of disease, guide biopsy, and/or monitor disease activity and patient response to therapy. Lymphoma, leukemia, and multiple myeloma commonly manifest as multiple parenchymal or perinephric lesions. Erdheim-Chester disease and Rosai-Dorfman disease, rare forms of multisystemic histiocytosis, are often identified as perinephric and periureteral masses. Renal abnormalities depicted at imaging in patients with sickle cell disease include renal enlargement, papillary necrosis, and renal medullary carcinoma. Sickle cell disease, along with other causes of intravascular hemolysis, can also lead to hemosiderosis of the renal cortex. Thrombosis of renal veins is sometimes seen in patients with coagulation disorders but more often occurs in association with certain malignancies and nephrotic syndrome. Immunoglobulin G4-related sclerosing disease is another multisystem process that often produces focal renal lesions, seen along with involvement of more characteristic organs such as the pancreas. Perinephric lesions with calcifications should raise the possibility of secondary amyloidosis, especially in patients with a history of lymphoma and multiple myeloma. Although the imaging patterns of renal and perinephric involvement are usually not specific for a single entity, and the same entity can manifest with different or overlapping patterns, familiarity with these patterns and key clinical and histopathologic features may help to narrow the differential diagnosis and determine the next step of care. (©)RSNA, 2016.
Topics: Diagnosis, Differential; Hematologic Diseases; Humans; Kidney Diseases; Renal Circulation
PubMed: 27257766
DOI: 10.1148/rg.2016150213