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Renal and renal sinus fat volumes as quantified by magnetic resonance imaging in subjects with prediabetes, diabetes, and normal glucose tolerance. PLoS One 2020; 15:e0216635. [PMID: 32074103 PMCID: PMC7029849 DOI: 10.1371/journal.pone.0216635] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 02/03/2020] [Indexed: 12/17/2022] Open
Abstract
Purpose We hypothesize that MRI-based renal compartment volumes, particularly renal sinus fat as locally and potentially independently acting perivascular fat tissue, increase with glucose intolerance. We therefore analyze the distribution of renal volumes in individuals with normal glucose levels and prediabetic and diabetic individuals and investigate potential associations with other typical cardiometabolic biomarkers. Material and methods The sample comprised N = 366 participants who were either normoglycemic (N = 230), had prediabetes (N = 87) or diabetes (N = 49), as determined by Oral Glucose Tolerance Test. Other covariates were obtained by standardized measurements and interviews. Whole-body MR measurements were performed on a 3 Tesla scanner. For assessment of the kidneys, a coronal T1w dual-echo Dixon and a coronal T2w single shot fast spin echo sequence were employed. Stepwise semi-automated segmentation of the kidneys on the Dixon-sequences was based on thresholding and geometric assumptions generating volumes for the kidneys and sinus fat. Inter- and intra-reader variability were determined on a subset of 40 subjects. Associations between glycemic status and renal volumes were evaluated by linear regression models, adjusted for other potential confounding variables. Furthermore, the association of renal volumes with visceral adipose tissue was assessed by linear regression models and Pearson’s correlation coefficient. Results Renal volume, renal sinus volume and renal sinus fat increased gradually from normoglycemic controls to individuals with prediabetes to individuals with diabetes (renal volume: 280.3±64.7 ml vs 303.7±67.4 ml vs 320.6±77.7ml, respectively, p < 0.001). After adjustment for age and sex, prediabetes and diabetes were significantly associated to increased renal volume, sinus volume (e.g. βPrediabetes = 10.1, 95% CI: [6.5, 13.7]; p<0.01, βDiabetes = 11.86, 95% CI: [7.2, 16.5]; p<0.01) and sinus fat (e.g. βPrediabetes = 7.13, 95% CI: [4.5, 9.8]; p<0.001, βDiabetes = 7.34, 95% CI: [4.0, 10.7]; p<0.001). Associations attenuated after adjustment for additional confounders were only significant for prediabetes and sinus volume (ß = 4.0 95% CI [0.4, 7.6]; p<0.05). Hypertension was significantly associated with increased sinus volume (β = 3.7, 95% CI: [0.4, 7.0; p<0.05]) and absolute sinus fat volume (β = 3.0, 95% CI: [0.7, 5.3]; p<0.05). GFR and all renal volumes were significantly associated as well as urine creatinine levels and renal sinus volume (β = 1.6, 95% CI: [0.1, 2.9]; p<0.05). Conclusion Renal volume and particularly renal sinus fat volume already increases significantly in prediabetic subjects and is significantly associated with VAT. This shows, that renal sinus fat is a perivascular adipose tissue, which early undergoes changes in the development of metabolic disease. Our findings underpin that renal sinus fat is a link between metabolic disease and associated chronic kidney disease, making it a potential imaging biomarker when assessing perivascular adipose tissue.
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Lee CJ, Gardiner BS, Ngo JP, Kar S, Evans RG, Smith DW. Accounting for oxygen in the renal cortex: a computational study of factors that predispose the cortex to hypoxia. Am J Physiol Renal Physiol 2017; 313:F218-F236. [DOI: 10.1152/ajprenal.00657.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/24/2017] [Accepted: 04/05/2017] [Indexed: 12/21/2022] Open
Abstract
We develop a pseudo-three-dimensional model of oxygen transport for the renal cortex of the rat, incorporating both the axial and radial geometry of the preglomerular circulation and quantitative information regarding the surface areas and transport from the vasculature and renal corpuscles. The computational model was validated by simulating four sets of published experimental studies of renal oxygenation in rats. Under the control conditions, the predicted cortical tissue oxygen tension ([Formula: see text]) or microvascular oxygen tension (µPo2) were within ±1 SE of the mean value observed experimentally. The predicted [Formula: see text] or µPo2 in response to ischemia-reperfusion injury, acute hemodilution, blockade of nitric oxide synthase, or uncoupling mitochondrial respiration, were within ±2 SE observed experimentally. We performed a sensitivity analysis of the key model parameters to assess their individual or combined impact on the predicted [Formula: see text] and µPo2. The model parameters analyzed were as follows: 1) the major determinants of renal oxygen delivery ([Formula: see text]) (arterial blood Po2, hemoglobin concentration, and renal blood flow); 2) the major determinants of renal oxygen consumption (V̇o2) [glomerular filtration rate (GFR) and the efficiency of oxygen utilization for sodium reabsorption (β)]; and 3) peritubular capillary surface area (PCSA). Reductions in PCSA by 50% were found to profoundly increase the sensitivity of [Formula: see text] and µPo2 to the major the determinants of [Formula: see text] and V̇o2. The increasing likelihood of hypoxia with decreasing PCSA provides a potential explanation for the increased risk of acute kidney injury in some experimental animals and for patients with chronic kidney disease.
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Affiliation(s)
- Chang-Joon Lee
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Bruce S. Gardiner
- School of Engineering and Information Technology, Murdoch University, Perth, Western Australia, Australia; and
| | - Jennifer P. Ngo
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology, Monash University, Melbourne, Sydney, Australia
| | - Saptarshi Kar
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Roger G. Evans
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology, Monash University, Melbourne, Sydney, Australia
| | - David W. Smith
- Faculty of Engineering and Mathematical Sciences, The University of Western Australia, Perth, Western Australia, Australia
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Akbari M, Goodarzi N, Tavafi M. Stereological assessment of normal Persian squirrels (Sciurus anomalus) kidney. Anat Sci Int 2016; 92:267-274. [DOI: 10.1007/s12565-016-0332-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 02/03/2016] [Indexed: 10/22/2022]
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Bankir L, Roussel R, Bouby N. Protein- and diabetes-induced glomerular hyperfiltration: role of glucagon, vasopressin, and urea. Am J Physiol Renal Physiol 2015; 309:F2-23. [DOI: 10.1152/ajprenal.00614.2014] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 04/13/2015] [Indexed: 12/21/2022] Open
Abstract
A single protein-rich meal (or an infusion of amino acids) is known to increase the glomerular filtration rate (GFR) for a few hours, a phenomenon known as “hyperfiltration.” It is important to understand the factors that initiate this upregulation because it becomes maladaptive in the long term. Several mediators and paracrine factors have been shown to participate in this upregulation, but they are not directly triggered by protein intake. Here, we explain how a rise in glucagon and in vasopressin secretion, directly induced by protein ingestion, might be the initial factors triggering the hepatic and renal events leading to an increase in the GFR. Their effects include metabolic actions in the liver and stimulation of sodium chloride reabsorption in the thick ascending limb. Glucagon is not only a glucoregulatory hormone. It is also important for the excretion of nitrogen end products by stimulating both urea synthesis in the liver (along with gluconeogenesis from amino acids) and urea excretion by the kidney. Vasopressin allows the concentration of nitrogenous end products (urea, ammonia, etc.) and other protein-associated wastes in a hyperosmotic urine, thus allowing a very significant water economy characteristic of all terrestrial mammals. No hyperfiltration occurs in the absence of one or the other hormone. Experimental results suggest that the combined actions of these two hormones, along with the complex intrarenal handling of urea, lead to alter the composition of the tubular fluid at the macula densa and to reduce the intensity of the signal activating the tubuloglomerular feedback control of GFR, thus allowing GFR to raise. Altogether, glucagon, vasopressin, and urea contribute to set up the best compromise between efficient urea excretion and water economy.
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Affiliation(s)
- Lise Bankir
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Paris Diderot, Sorbonne-Paris-Cité, Paris, France; and
| | - Ronan Roussel
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Paris Diderot, Sorbonne-Paris-Cité, Paris, France; and
- Diabétologie Endocrinologie Nutrition, DHU FIRE, Hôpital Bichat, AP-HP, Paris, France
| | - Nadine Bouby
- INSERM UMRS 1138, Centre de Recherche des Cordeliers, Paris, France
- Université Paris Diderot, Sorbonne-Paris-Cité, Paris, France; and
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Lenihan CR, Busque S, Derby G, Blouch K, Myers BD, Tan JC. Longitudinal study of living kidney donor glomerular dynamics after nephrectomy. J Clin Invest 2015; 125:1311-8. [PMID: 25689253 DOI: 10.1172/jci78885] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/11/2014] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Over 5,000 living kidney donor nephrectomies are performed annually in the US. While the physiological changes that occur early after nephrectomy are well documented, less is known about the long-term glomerular dynamics in living donors. METHODS We enrolled 21 adult living kidney donors to undergo detailed long-term clinical, physiological, and radiological evaluation pre-, early post- (median, 0.8 years), and late post- (median, 6.3 years) donation. A morphometric analysis of glomeruli obtained during nephrectomy was performed in 19 subjects. RESULTS Donors showed parallel increases in single-kidney renal plasma flow (RPF), renocortical volume, and glomerular filtration rate (GFR) early after the procedure, and these changes were sustained through to the late post-donation period. We used mathematical modeling to estimate the glomerular ultrafiltration coefficient (Kf), which also increased early and then remained constant through the late post-donation study. Assuming that the filtration surface area (and hence, Kf) increased in proportion to renocortical volume after donation, we calculated that the 40% elevation in the single-kidney GFR observed after donation could be attributed exclusively to an increase in the Kf. The prevalence of hypertension in donors increased from 14% in the early post-donation period to 57% in the late post-donation period. No subjects exhibited elevated levels of albuminuria. CONCLUSIONS Adaptive hyperfiltration after donor nephrectomy is attributable to hyperperfusion and hypertrophy of the remaining glomeruli. Our findings point away from the development of glomerular hypertension following kidney donation. TRIAL REGISTRATION Not applicable. FUNDING. NIH (R01DK064697 and K23DK087937); Astellas Pharma US; the John M. Sobrato Foundation; the Satellite Extramural Grant Foundation; and the American Society of Nephrology.
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Lenihan CR, Busque S, Derby G, Blouch K, Myers BD, Tan JC. The association of predonation hypertension with glomerular function and number in older living kidney donors. J Am Soc Nephrol 2014; 26:1261-7. [PMID: 25525178 DOI: 10.1681/asn.2014030304] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 09/01/2014] [Indexed: 11/03/2022] Open
Abstract
The effect of preexisting hypertension on living donor nephron number has not been established. In this study, we determined the association between preexisting donor hypertension and glomerular number and volume and assessed the effect of predonation hypertension on postdonation BP, adaptive hyperfiltration, and compensatory glomerular hypertrophy. We enrolled 51 living donors to undergo physiologic, morphometric, and radiologic evaluations before and after kidney donation. To estimate the number of functioning glomeruli (NFG), we divided the whole-kidney ultrafiltration coefficient (Kf) by the single-nephron ultrafiltration coefficient (SNKf). Ten donors were hypertensive before donation. We found that, in donors ages >50 years old, preexisting hypertension was associated with a reduction in NFG. In a comparison of 10 age- and sex-matched hypertensive and normotensive donors, we observed more marked glomerulopenia in hypertensive donors (NFG per kidney, 359,499±128,929 versus 558,239±205,152; P=0.02). Glomerulopenia was associated with a nonsignificant reduction in GFR in the hypertensive group (89±12 versus 95±16 ml/min per 1.73 m(2)). We observed no difference in the corresponding magnitude of postdonation BP, hyperfiltration capacity, or compensatory renocortical hypertrophy between hypertensive and normotensive donors. Nevertheless, we propose that the greater magnitude of glomerulopenia in living kidney donors with preexisting hypertension justifies the need for long-term follow-up studies.
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Affiliation(s)
| | - Stephan Busque
- Department of Surgery, Stanford University School of Medicine, Palo Alto, California
| | | | | | | | - Jane C Tan
- Division of Nephrology, Department of Medicine and
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Bolat D, Bahar S, Tipirdamaz S, Selcuk ML. Comparison of the Morphometric Features of the Left and Right Horse Kidneys: A Stereological Approach. Anat Histol Embryol 2013; 42:448-52. [DOI: 10.1111/ahe.12036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 12/30/2012] [Indexed: 11/29/2022]
Affiliation(s)
- D. Bolat
- Department of Anatomy; Faculty of Veterinary Medicine; University of Kirikkale; Campus 71451 Yahsihan Kirikkale Turkey
| | - S. Bahar
- Department of Anatomy; Faculty of Veterinary Medicine; University of Selcuk; Campus 42075 Selcuklu Konya Turkey
| | - S. Tipirdamaz
- Department of Anatomy; Faculty of Veterinary Medicine; University of Selcuk; Campus 42075 Selcuklu Konya Turkey
| | - M. L. Selcuk
- Department of Anatomy; Faculty of Veterinary Medicine; University of Selcuk; Campus 42075 Selcuklu Konya Turkey
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Thelwall PE, Taylor R, Marshall SM. Non-invasive investigation of kidney disease in type 1 diabetes by magnetic resonance imaging. Diabetologia 2011; 54:2421-9. [PMID: 21533898 DOI: 10.1007/s00125-011-2163-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 03/23/2011] [Indexed: 12/15/2022]
Abstract
AIMS/HYPOTHESIS Pathophysiological abnormalities in early diabetic nephropathy are poorly understood. We employed MRI to characterise renal perfusion, tissue oxygenation and kidney size in non-diabetic volunteers and type 1 diabetic patients without and with early renal disease. METHODS We studied ten control participants (C; age 40.0 [range 31-54] years), nine longstanding normotensive type 1 diabetic patients (T1Normo; age 40.1 [31-50] years, estimated glomerular filtration rate [eGFR] 83.4 ± 10.6 ml min(-1) 1.73 m(-2)) and eight microalbuminuric type 1 diabetic patients (T1Micro; age 42.4 [33-52] years, eGFR 71.6 ± 13.7 ml min(-1) 1.73 m(-2)). Six microalbuminuric patients were restudied after 4 weeks without renin-angiotensin-aldosterone system inhibitors. Phase contrast angiography and kidney blood oxygen level dependent (BOLD) (R(2)(*)) MRI were performed, before and during water diuresis. Contrast-enhanced MRI was performed at baseline urine flow rate. Renal artery flow, renal vascular resistance (RVR), cortical and medullary volumes, and R(2)(*) were determined. RESULTS Renal cortical and medullary volumes were similar in all groups (cortex: C 108 ± 16, T1Normo 112 ± 21, T1Micro 111 ± 10 cm(3)/1.73 m(2); medulla: C 35 ± 14, T1Normo 29 ± 10, 33 ± 6 cm(3)/1.73 m(2)). RVR increased from control to normoalbuminuric to microalbuminuric type 1 diabetic patients (C 0.061 ± 0.018, T1Normo 0.077 ± 0.014, T1Micro 0.093 ± 0.024 mmHg ml(-1) min(-1) 1.73 m(-2), ANOVA p = 0.012). RVR correlated inversely with eGFR in normoalbuminuric, but not in microalbuminuric diabetic patients. Renal artery flow was lower in the whole diabetes cohort (control 740 ± 205 vs diabetes 591 ± 128 ml min(-1) 1.73 m(-2), p = 0.035). CONCLUSIONS/INTERPRETATION Cortical and medullary volumes remain normal in early diabetic nephropathy. Decreased renal flow in longstanding normoalbuminuric type 1 diabetic patients may reflect intrarenal vascular stiffening, whereas in the microalbuminuric patients it may also reflect increased intraglomerular pressure.
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Affiliation(s)
- P E Thelwall
- Newcastle Magnetic Resonance Centre, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne NE4 5PL, UK.
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Michell A, Debnam E, Unwin R. Regulation of Renal Function by the Gastrointestinal Tract: Potential Role of Gut-Derived Peptides and Hormones. Annu Rev Physiol 2008; 70:379-403. [DOI: 10.1146/annurev.physiol.69.040705.141330] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A.R. Michell
- Department of Biochemical Pharmacology, William Harvey Research Institute, St. Bartholomew's Hospital Medical School, London EC1M 6BQ, United Kingdom;
| | - E.S. Debnam
- Department of Physiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
| | - R.J. Unwin
- Department of Physiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
- Centre for Nephrology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
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Ming Z, Lautt WW. Intrahepatic adenosine-mediated activation of hepatorenal reflex is via A1 receptors in rats. Can J Physiol Pharmacol 2007; 84:1177-84. [PMID: 17218982 DOI: 10.1139/y06-063] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies have shown that intrahepatic adenosine is involved in activation of the hepatorenal reflex that regulates renal sodium and water excretion. The present study aims to determine which subtype of adenosine receptors is implicated in the process. Mean arterial pressure, portal venous pressure and flow, and renal arterial flow were monitored in pentobarbital anesthetized rats. Urine was collected from the bladder. Intraportal administration of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective adenosine A1 receptor antagonist, increased urine flow by 24%, 89%, and 143% at the dose of 0.01, 0.03, and 0.1 mg x kg(-1), respectively; in contrast, DPCPX, when administered intravenously at the same doses, only increased urine flow by 0%, 18%, and 36%. The increases in urine flow induced by intraportal administration of DPCPX were abolished in rats with liver denervation. Intrahepatic infusion of adenosine significantly decreased urine flow and this response was abolished by intraportal administration of DPCPX. Neither intraportal nor intravenous administration of 3,7-dimethyl-1-propargylxanthine, a selective adenosine A2 receptor antagonist, showed significant influence on urine flow. Systemic arterial pressure, renal blood flow and glomerular filtration rate were unaltered by the administration of any of the drugs. In conclusion, intrahepatic adenosine A1 receptors are responsible for the adenosine-mediated hepatorenal reflex that regulates renal water and sodium excretion.
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Affiliation(s)
- Zhi Ming
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, 753 McDermot Avenue, Winnipeg, MB R3E 0T6, Canada
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Topcu SO, Pedersen M, Nørregaard R, Wang G, Knepper M, Djurhuus JC, Nielsen S, Jørgensen TM, Frøkiaer J. Candesartan prevents long-term impairment of renal function in response to neonatal partial unilateral ureteral obstruction. Am J Physiol Renal Physiol 2007; 292:F736-48. [PMID: 17032940 DOI: 10.1152/ajprenal.00241.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Angiotensin II (ANG II) plays an important role in the development of obstructive nephropathy. Here, we examined the effects of the ANG II receptor type 1 (AT1R) blockade using candesartan on long-term renal molecular and functional changes in response to partial unilateral ureteral obstruction (PUUO). Newborn rats were subjected to severe PUUO or sham operation (Sham) within the first 48 h of life. Candesartan was provided in the drinking water (10 mg·kg−1·day−1) from day 21 of life until 10 wk of age. Renal blood flow (RBF) was evaluated by MRI, glomerular filtration rate (GFR) was measured using the renal clearance of51Cr-EDTA, and the renal expression of Na-K-ATPase and the collecting duct water channel aquaporin-2 (AQP2) was examined by immunoblotting and immunocytochemistry. At 10 wk of age, PUUO significantly reduced RBF (0.8 ± 0.1 vs. 1.6 ± 0.1 ml·min−1·100 g body wt−1; P < 0.05) and GFR (37 ± 16 vs. 448 ± 111 μl·min−1·100 g body wt−1; P < 0.05) compared with Sham. Candesartan prevented the RBF reduction (PUUO+CAN: 1.6 ± 0.2 vs. PUUO: 0.8 ± 0.1 ml·min−1·100 g body wt−1; P < 0.05) and attenuated the GFR reduction (PUUO+CAN: 265 ± 68 vs. PUUO: 37 ± 16 μl·min−1·100 g body wt−1; P < 0.05). PUUO was also associated with a significant downregulation in the expression of Na-K-ATPase (75 ± 12 vs. 100 ± 5%, P < 0.05) and AQP2 (52 ± 15 vs. 100 ± 4%, P < 0.05), which were also prevented by candesartan (Na-K-ATPase: 103 ± 8 vs. 100 ± 5% and AQP2: 74 ± 13 vs. 100 ± 4%). These findings were confirmed by immunocytochemistry. Consistent with this, candesartan treatment partly prevented the reduction in solute free water reabsorption and attenuated fractional sodium excretion in rats with PUUO. In conclusion, candesartan prevents or attenuates the reduction in RBF, GFR and dysregulation of AQP2 and Na-K-ATPase in response to congenital PUUO in rats, suggesting that AT1R blockade may protect the neonatally obstructed kidney against development of obstructive nephropathy.
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Affiliation(s)
- Sukru Oguzkan Topcu
- The Water and Salt Research Ctr., Institute of Clinical Medicine, University of Aarhus, DK-8200 Aarhus, Denmark
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Karstoft K, Lødrup AB, Dissing TH, Sørensen TS, Nyengaard JR, Pedersen M. Different strategies for MRI measurements of renal cortical volume. J Magn Reson Imaging 2007; 26:1564-71. [DOI: 10.1002/jmri.21121] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Lee YR, Lee KB. Reliability of magnetic resonance imaging for measuring the volumetric indices in autosomal-dominant polycystic kidney disease: correlation with hypertension and renal function. Nephron Clin Pract 2006; 103:c173-80. [PMID: 16636585 DOI: 10.1159/000092915] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Accepted: 12/30/2005] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The purpose of this study was to determine if renal volumetric indices can be accurately measured using MRI, and if these volumetric indices are associated with hypertension and renal function in patients with autosomal-dominant polycystic kidney disease (ADPKD). METHODS For testing the accuracy of the MRI-based volume measurements that we proposed for clinical trial, we designed phantoms to simulate cysts within the kidney. Fifty-six patients with ADPKD were included in this study, and their respiratory compensated T2-weighted fast spin-echo images were acquired. The total kidney volume (Vt), cyst volume (Vc), and noncystic parenchymal volume (Vp) were measured and the percent cyst volume (Pc) was calculated. These volumetric indices were compared with the disease progression in the ADPKD patients. RESULTS The MRI measures of the phantoms were accurate. The Vt, Vc and Pc were significantly greater in the hypertensive group (n = 35) than in the normotensive group (n = 21) (p < 0.01). The Vt, Vc and Pc were significantly greater in the renal failure group (n = 23) than in the normal renal function group (n = 33) (p < 0.01). The Vt, Vc, and Pc were inversely correlated with the creatinine clearance. CONCLUSION MRI is a reliable method to measure renal volumetric indices. The MRI-based volume measurements can be employed as useful markers for the progression of disease in ADPKD patients.
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Affiliation(s)
- Young Rae Lee
- Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Jong-no ku, Seoul, Korea
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Dickinson H, Walker DW, Cullen-McEwen L, Wintour EM, Moritz K. The spiny mouse (Acomys cahirinus) completes nephrogenesis before birth. Am J Physiol Renal Physiol 2005; 289:F273-9. [PMID: 15741606 DOI: 10.1152/ajprenal.00400.2004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The spiny mouse is relatively mature at birth. We hypothesized that like other organs, the kidney may be more developed in the spiny mouse at birth, than in other rodents. If nephrogenesis is complete before birth, the spiny mouse may provide an excellent model with which to study the effects of an altered intrauterine environment on renal development. Due to its desert adaptation, the spiny mouse may have a reduced cortex-to-medulla ratio but an equivalent total nephron number to the C57/BL mouse. Kidneys were collected from fetal and neonatal spiny mice and sectioned for gross examination of metanephric development. Kidneys were collected from adult spiny mice (10 wk of age), and glomerular number, volume, and cortex-to-medulla ratios were determined using unbiased stereology. Nephrogenesis is complete in spiny mouse kidneys before birth. Metanephrogenesis begins at ∼ day 18, and by day 38 of a 40-day gestation, the nephrogenic zone is no longer present. Spiny mice have a significantly ( P < 0.001) lower total nephron number compared with C57/BL mice, although the total glomerular volume is similar. The cortex-to-medulla ratio of the spiny mouse is significantly ( P < 0.01) smaller. The spiny mouse is the first rodent species shown to complete nephrogenesis before birth. This makes it an attractive candidate for the study of fetal and neonatal kidney development and function. The reduced total nephron number and cortex-to-medulla ratio in the spiny mouse may contribute to its ability to highly concentrate its urine under stressful conditions (i.e., dehydration).
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Affiliation(s)
- Hayley Dickinson
- Department of Physiology, Monash University, Clayton, Victoria, Australia.
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Rasch R, Lauszus F, Thomsen JS, Flyvbjerg A. Glomerular structural changes in pregnant, diabetic, and pregnant-diabetic rats. APMIS 2005; 113:465-72. [PMID: 16086816 DOI: 10.1111/j.1600-0463.2005.apm_587.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Kidneys enlarge both during pregnancy and in diabetes. The enlargement and morphology of glomeruli was studied during pregnancy and in diabetes in order to examine possible similarities, differences, and interactions in the growth in these conditions. Morphometric investigations were performed on glomeruli in pregnant rats, in rats with 2 weeks' diabetes, and in pregnant-diabetic rats. Kidneys were enlarged 22% in the midterm pregnant rats compared with controls, 74% in diabetic rats, and a further 21% in pregnant-diabetic rats. Glomerular volume was enlarged by 26% during midterm pregnancy in normal animals. Diabetes induced an enlargement in glomerular volume of 58% and a further 18% in midterm diabetic animals due to pregnancy. Within the glomerulus, pregnancy in normal animals induced minor non-significant changes. Diabetes induced significant increase in several parameters: mesangial volume and cell volume, capillary and glomerular basement membrane volume, capillary wall surface area, foot process width, filtration slit length, and nuclear number. Pregnancy in diabetic animals induced no significant additional changes. In conclusion, kidney enlargement in pregnancy shows very few glomerular changes in either normal or diabetic animals. Enlargement of glomeruli in diabetes involves hypertrophy and hyperplasia concurrent with several morphological changes within the glomerulus.
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Affiliation(s)
- Ruth Rasch
- Department of Cell Biology, Institute of Anatomy, University of Aarhus, Aarhus, Denmark.
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Ahloulay M, Bankir L, Lugnier C, Le Bec A, Poirel O, Moreau R, Lebrec D. Cyclic AMP-phosphodiesterases inhibitor improves sodium excretion in rats with cirrhosis and ascites. Liver Int 2005; 25:403-9. [PMID: 15780066 DOI: 10.1111/j.1478-3231.2005.01034.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
BACKGROUND The mechanisms responsible for renal dysfunction and sodium retention in cirrhosis remain unclear. Cyclic AMP (cAMP) regulates sodium reabsorption in the proximal nephron. This study investigates the role of cAMP metabolism in renal dysfunction in cirrhosis. METHODS Renal function was studied by the clearance technique in anesthetized control and cirrhotic rats with or without ascites. cAMP phosphodiesterase (PDE) activity was measured in the renal cortex in vitro. Moroever, the effects on renal function of the intravenous administration of cAMP and rolipram, a powerful and specific cAMP-PDE4 inhibitor, were evaluated. RESULTS In control and in non-ascitic cirrhotic rats, cAMP administration significantly increased sodium and phosphate excretions, but did not change these excretions in cirrhotic rats with ascites. cAMP-PDE activity was higher in ascitic than in control rats (P < 0.05). Rolipram infusion significantly increased sodium and phosphate excretion only in cirrhotic rats with ascites. CONCLUSION These results suggest that increased renal cAMP-PDE activity is responsible for resistance to the natriuretic effects of cAMP in cirrhosis and plays a role in the development of ascites.
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Affiliation(s)
- Mina Ahloulay
- Laboratoire d'Hémodynamique Splanchnique et de Biologie Vasculaire, INSERM U-481, Hôpital Beaujon, 92118 Clichy, France
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17
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Carey GB, Wotjukiewicz LJ, Goodman JM, Reineck KE, Overman KC. Extracellular cyclic AMP and adenosine appearance in adipose tissue of Sus scrofa: effects of exercise. Exp Biol Med (Maywood) 2004; 229:1026-32. [PMID: 15522838 DOI: 10.1177/153537020422901006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cyclic AMP (cAMP) appears extracellularly in a variety of tissues including brain, liver, and kidney; whether it appears in adipose tissue and responds to physiological perturbation is unknown. The purpose of this study was to examine adipose tissue extracellular cAMP appearance and metabolism in situ and in vitro in physiologically challenged animals. Littermate swine were either sedentary or exercise trained on a treadmill for 3 months and subjected to acute exercise on experiment day. In situ, microdialysis probes in subcutaneous back fat were perfused before, during, and after animals performed 20 mins of acute exercise, and dialysate was analyzed for cAMP and adenosine. In vitro, isolated adipocytes were hormonally stimulated to provoke cAMP synthesis and efflux, and plasma membrane phosphodiesterase and 5'-nucleotidase activities were measured. Extracellular cAMP and adenosine levels in adipose tissue of sedentary swine averaged 5.2 +/- 1.7 and 863 +/- 278 nM, respectively. Exercise training tended to increase extracellular cAMP (11.3 +/- 1.7 nM) and reduce extracellular adenosine (438 +/- 303 nM), although neither change was statistically significant. Acute exercise caused a significant 3-fold and 16-fold increase in extracellular cAMP and adenosine, respectively, compared to rest. These changes occurred despite a 2- to 3-fold increase in adipose tissue blood flow during acute exercise. In vitro, cAMP efflux from exercise-trained swine was 42% greater than that from adipocytes of sedentary swine, yet adipocyte plasma membranes from exercise-trained and sedentary swine did not differ in maximal phosphodiesterase and 5'-nucleotidase activities. We conclude that cAMP appears extracellularly in swine adipose tissue and that the levels of extracellular cAMP and adenosine in intact swine adipose tissue are influenced by both acute and chronic exercise. The subsequent impact of the changes in these biochemicals on local cellular metabolism and growth remains to be determined.
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Affiliation(s)
- Gale B Carey
- Department of Animal and Nutritional Sciences, 403 Kendall Hall, University of New Hampshire, Durham, NH 03824, USA.
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18
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Fulladosa X, Moreso F, Narváez JA, Grinyó JM, Serón D. Estimation of total glomerular number in stable renal transplants. J Am Soc Nephrol 2004; 14:2662-8. [PMID: 14514746 DOI: 10.1097/01.asn.0000088025.33462.b0] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Glomerular number (N(g)) is considered a major determinant of renal function and outcome. In the dog, it has been shown that Ng can be estimated with reasonable precision in vivo by means of a renal biopsy and magnetic resonance imaging (MRI). Thus, this method was applied to study anatomoclinical correlations in stable human renal transplants. Thirty-nine stable renal transplants were included. A protocol renal allograft biopsy was done at 4 mo. Biopsies were evaluated according to Banff criteria. Glomerular volume fraction (Vv(glom/cortex)) was measured by means of a point-counting method, and mean glomerular volume (V(g)) was estimated by means of Weibel and Gomez (V(g)-W&G) and maximal profile area (V(g)-MPA) methods. MRI was used to estimate renal cortical volume (V(cortex)). N(g) was calculated as (Vv(glom/cortex) x V(cortex))/V(g). GFR was estimated by the inulin clearance. Ten age-matched donor biopsies served as controls for V(g). Histologic diagnosis was as follows: normal (n = 20), borderline (n = 7), acute rejection (n = 1), and chronic allograft nephropathy (n = 11). Vv(glom/cortex) was 3.4 +/- 1.1%, V(cortex) was 167 +/- 46 cm(3), V(g)-W&G was 3.2 +/- 1.2 x 10(6) micro m(3), and V(g)-MPA was 3.3 +/- 1.0 x 10(6) micro m(3). V(g)-W&G in donor and recipient biopsies was not different (3.6 +/- 1.1 versus 3.2 +/- 1.2 x 10(6) micro m(3)). Total glomerular number estimated by means of V(g)-W&G (N(g)-W&G) was 0.73 +/- 0.33 x 10(6) and by V(g)-MPA (N(g)-MPA) was 0.74 +/- 0.31 x 10(6). A positive correlation between GFR and N(g)-W&G (r = 0.47, P = 0.002) was observed. Furthermore, the older the donor, the higher V(g)-W&G (r = 0.37, P = 0.01) and the lower N(g)-W&G (r = -0.40, P = 0.01). Total glomerular number can be estimated in stable renal allografts by means of a renal biopsy and MRI. Our data show that N(g) depends on donor age and positively correlates with GFR.
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Affiliation(s)
- Xavier Fulladosa
- Nephrology Department, Hospital Universitari de Bellvitge, Barcelona, Spain.
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19
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Abstract
This review comprises an overview of the current knowledge on experimental partial unilateral ureteral obstruction (PUUO) and a summary of our latest original experimental PUUO studies in rats. Neonatal PUUO is the type of obstruction that is most often encountered in pediatric clinical practice. However, the pathogenesis of PUUO is still incompletely understood. Most of our knowledge on PUUO has been derived from experimental studies in a variety of animal models. Although progress has been made, the natural history of congenital hydronephrosis is still incompletely described. The effects on kidney functions of long-term urinary tract obstruction, especially PUUO, have been less intensively studied. Recently, we created models with mild and severe PUUO in young rats by embedding the upper one fourth or the upper two thirds of the left ureter into the psoas muscle, respectively. Thereafter, the technique was used to create mild and severe PUUO in newborn rats and magnetic resonance imaging studies showed that both mild and severe obstruction caused a time-dependent decrease in renal blood flow. Compensatory increase in total kidney volume and renal vein blood flow in contralateral non-obstructed kidneys was not detectable when functional deterioration in the partially obstructed kidneys was present. Finally, we investigated the dynamic changes in renal relative signal intensity (RSI) of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) using magnetic resonance imaging in rats with partial, complete unilateral ureteral obstruction and sham-operated controls. The results showed that changes in Gd-DTPA RSI are compatible with the known physiological and anatomical changes in kidneys in response to ureteral obstruction and useful for distinguishing an obstructed from a non-obstructed collecting system and also for differentiating a partially obstructed from a completely obstructed collecting system.
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Affiliation(s)
- Jian Guo Wen
- First Teaching Hospital of Zhengzhou University, Zhengzhou City, P.R. China.
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Bankir L, Ahloulay M, Devreotes PN, Parent CA. Extracellular cAMP inhibits proximal reabsorption: are plasma membrane cAMP receptors involved? Am J Physiol Renal Physiol 2002; 282:F376-92. [PMID: 11832418 DOI: 10.1152/ajprenal.00202.2001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Glucagon binding to hepatocytes has been known for a long time to not only stimulate intracellular cAMP accumulation but also, intriguingly, induce a significant release of liver-borne cAMP in the blood. Recent experiments have shown that the well-documented but ill-understood natriuretic and phosphaturic actions of glucagon are actually mediated by this extracellular cAMP, which inhibits the reabsorption of sodium and phosphate in the renal proximal tubule. The existence of this "pancreato-hepatorenal cascade" indicates that proximal tubular reabsorption is permanently influenced by extracellular cAMP, the concentration of which is most probably largely dependent on the insulin-to-glucagon ratio. The possibility that renal cAMP receptors may be involved in this process is supported by the fact that cAMP has been shown to bind to brush-border membrane vesicles. In other cell types (i.e., adipocytes, erythrocytes, glial cells, cardiomyocytes), cAMP eggress and/or cAMP binding have also been shown to occur, suggesting additional paracrine effects of this nucleotide. Although not yet identified in mammals, cAMP receptors (cARs) are already well characterized in lower eukaryotes. The amoeba Dictyostelium discoideum expresses four different cARs during its development into a multicellular organism. cARs belong to the superfamily of seven transmembrane domain G protein-coupled receptors and exhibit a modest homology with the secretin receptor family (which includes PTH receptors). However, the existence of specific cAMP receptors in mammals remains to be demonstrated. Disturbances in the pancreato-hepatorenal cascade provide an adequate pathophysiological understanding of several unexplained observations, including the association of hyperinsulinemia and hypertension, the hepatorenal syndrome, and the hyperfiltration of diabetes mellitus. The observations reviewed in this paper show that cAMP should no longer be regarded only as an intracellular second messenger but also as a first messenger responsible for coordinated hepatorenal functions, and possibly for paracrine regulations in several other tissues.
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Affiliation(s)
- Lise Bankir
- Institut National de la Santé et de la Recherche Médicale Unité 367, Institut du Fer à Moulin, 75005 Paris, France.
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Bak M, Thomsen K, Flyvbjerg A. Effects of the somatostatin analogue octreotide on renal function in conscious diabetic rats. Nephrol Dial Transplant 2001; 16:2002-7. [PMID: 11572888 DOI: 10.1093/ndt/16.10.2002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Studies performed during the last decade have indicated that growth hormone (GH) and insulin-like growth factors (IGFs) may mediate the early renal changes in diabetes mellitus, i.e. hypertrophy and hyperfiltration. This and other observations have led to the suggestion that GH/IGF inhibitors, such as long-acting somatostatin analogue (e.g. octreotide and lanreotide), may be useful in order to inhibit or prevent development of long-term diabetic complications. METHODS The present study examined the acute and chronic effects of octreotide on renal function following induction of streptozotocin (STZ)-diabetes in rats. The studies were carried out in conscious, non-fasted diabetic animals. RESULTS Chronic administration of octreotide for 7 days, from onset of diabetes, prevented the decrease of effective renal vascular resistance (ERVR), and the increases in filtration fraction (FF), glomerular filtration rate (GFR), and absolute proximal tubular fluid reabsorption (APR) induced by diabetes. The renal hypertrophy was only partially prevented. In the acute study, similar changes were observed in effective renal plasma flow (ERPF) and ERVR but FF increased and GFR remained unaltered. CONCLUSIONS Chronic but not acute treatment with octreotide prevented the renal hyperfiltration caused by diabetes. This effect is most likely due to an increase in afferent arteriolar resistance.
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Affiliation(s)
- M Bak
- Institute for Basic Psychiatric Research, Department of Biological Psychiatry, Aarhus University Hospital, Skovagervej, Risskov, Denmark.
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22
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Gaschen L, Schuurman HJ, Bruttel K, Tanner M, Beckmann N. MRI and ultrasonographic detection of morphologic and hemodynamic changes in chronic renal allograft rejection in the rat. J Magn Reson Imaging 2001; 13:232-41. [PMID: 11169829 DOI: 10.1002/1522-2586(200102)13:2<232::aid-jmri1034>3.0.co;2-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study is to describe the sonographic, MRI, and histopathologic findings in a rat model of chronic renal allograft rejection. MATERIALS AND METHODS Allogeneic renal grafts (male DA kidney into male Lewis rat with unilateral nephrectomy, N = 27) and syngeneic renal grafts (male Lewis kidney into male Lewis rat, N = 19) were examined serially with ultrasound, MRI, and histology. RESULTS Nonparametric Spearman rank correlation showed significance between the histologic score and the following parameters: the MRI score (r(s) = 0.91, P < 0.01, N = 46), the ultrasound score (r(s) = 0.9, P < 0.01, N = 46), the power Doppler score (r(s) = 0.86, P < 0.01, N = 46), and the MRI perfusion (r(s) = -0.80, P < 0.01, N = 45). Positive correlations were also found between the MRI volume estimations (graft r(s) = 0.49, P < 0.01, N = 46; native r(s) = 0.59, P < 0.01, N = 46), and the ultrasound volume estimations (graft r(s) = 0.39, P < 0.01, N = 45; native r(s) = 0.64, P < 0.01, N = 46) as well as with actual graft weight. CONCLUSIONS This study shows that both MRI and ultrasound can provide complementary, accurate information compared to histology in regard to the alterations in anatomy and hemodynamic changes associated with chronic allograft nephropathy.
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Affiliation(s)
- L Gaschen
- Transplantation Research, Novartis Pharma Inc., Kohlenstrasse 35, WSJ-386.526, CH-4002 Basel, Switzerland.
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Bak M, Thomsen K, Christiansen T, Flyvbjerg A. Renal enlargement precedes renal hyperfiltration in early experimental diabetes in rats. J Am Soc Nephrol 2000; 11:1287-1292. [PMID: 10864585 DOI: 10.1681/asn.v1171287] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The order of appearance between renal hypertrophy and hyperfunction in early experimental diabetes is still disputed. The reason for previous discrepant results is believed to be methodologic problems, as most previous studies of renal function have been performed in anesthetized animals. In the present study in nondiabetic and streptozotocin-diabetic animals, renal volume was measured by a noninvasive magnetic resonance imaging technique, while renal function parameters were measured in conscious, chronically catheterized animals. To avoid artifacts caused by the procedures associated with induction of streptozotocin-diabetes (fasting, brief anesthesia, and transient hypoglycemia) on renal growth and function, diabetic animals were injected with insulin to obtain euglycemia for 4 d before study start. At day 0, insulin administration was withdrawn and all animals developed hyperglycemia within 12 h. Renal volume and kidney function were measured on days 0, 1, 2, 3, 5, and 7. Renal enlargement was detectable at day 1 (20%) and reached an increase of 40% at day 7. No changes were seen in effective renal plasma flow or effective renal vascular resistance within the first 7 d after development of hyperglycemia. GFR tended to rise on day 5 and was increased by 16% at day 7. The absolute proximal reabsorption showed a pronounced rise (30%) at day 7, whereas no change was seen in the proximal tubular fluid output. It is concluded that renal enlargement precedes renal hyperfunction in the early phase after onset of experimental diabetes.
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Affiliation(s)
- Martin Bak
- Medical Research Laboratories, Institute of Experimental Clinical Research, Aarhus University Hospital, Denmark
- Institute for Basic Psychiatric Research, Aarhus University Hospital, Denmark
| | - Klaus Thomsen
- Institute for Basic Psychiatric Research, Aarhus University Hospital, Denmark
| | | | - Allan Flyvbjerg
- Medical Research Laboratories, Institute of Experimental Clinical Research, Aarhus University Hospital, Denmark
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Contralateral compensatory kidney growth in rats with partial unilateral ureteral obstruction monitored by magnetic resonance imaging. J Urol 1999; 162:1084-9. [PMID: 10458437 DOI: 10.1016/s0022-5347(01)68076-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We studied dynamic changes in total volume and renal vein blood flow in the kidneys contralateral to partial ureteral obstruction induced in newborn rats. MATERIALS AND METHODS Using magnetic resonance imaging we investigated changes in total kidney volume and renal vein blood flow in 20 rats with mild and 18 with severe partial ureteral obstruction that was induced on the left side 2 days after birth. A total of 15 sham operated control rats were also studied. Total kidney volume and renal vein blood flow were monitored sequentially every 2 to 6 weeks for a total of 24 weeks. Renal parenchymal volume measured in vivo by magnetic resonance imaging was compared with that measured in vitro at week 24. RESULTS Total volume and renal vein blood flow increased significantly in contralateral nonobstructed kidneys from week 14 and thereafter in rats with severe partial unilateral ureteral obstruction. At week 24 volume had increased by 22% and blood flow had increased by 25%. Volume and flow did not increase significantly in contralateral nonobstructed kidneys in rats with mild partial unilateral ureteral obstruction (p = 0.09). Before changes occurred in volume and blood flow in the contralateral nonobstructed kidneys, renal vein blood flow had decreased significantly from week 8 and thereafter in severely obstructed kidneys. In rats with mild partial unilateral ureteral obstruction renal vein blood flow decreased significantly in obstructed kidneys from week 18 and thereafter. Good correlation was noted between MRI in vivo and in vitro kidney volume measurements (r = 0.972, p <0.001). CONCLUSIONS A significant increase in total volume and renal vein blood flow in contralateral nonobstructed kidneys did not develop immediately after the onset of detectable functional deterioration in partially obstructed kidneys. Therefore, caution should be used when incorporating compensatory growth into surgical decision making.
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Wen JG, Ringgaard S, Frøkiaer J, Jørgensen TM, Stødkilde-Jørgensen H, Djurhuus JC. Contralateral compensatory kidney growth in rats with partial unilateral ureteral obstruction monitored by magnetic resonance imaging. J Urol 1999; 162:1084-9. [PMID: 10458437 DOI: 10.1097/00005392-199909000-00038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE We studied dynamic changes in total volume and renal vein blood flow in the kidneys contralateral to partial ureteral obstruction induced in newborn rats. MATERIALS AND METHODS Using magnetic resonance imaging we investigated changes in total kidney volume and renal vein blood flow in 20 rats with mild and 18 with severe partial ureteral obstruction that was induced on the left side 2 days after birth. A total of 15 sham operated control rats were also studied. Total kidney volume and renal vein blood flow were monitored sequentially every 2 to 6 weeks for a total of 24 weeks. Renal parenchymal volume measured in vivo by magnetic resonance imaging was compared with that measured in vitro at week 24. RESULTS Total volume and renal vein blood flow increased significantly in contralateral nonobstructed kidneys from week 14 and thereafter in rats with severe partial unilateral ureteral obstruction. At week 24 volume had increased by 22% and blood flow had increased by 25%. Volume and flow did not increase significantly in contralateral nonobstructed kidneys in rats with mild partial unilateral ureteral obstruction (p = 0.09). Before changes occurred in volume and blood flow in the contralateral nonobstructed kidneys, renal vein blood flow had decreased significantly from week 8 and thereafter in severely obstructed kidneys. In rats with mild partial unilateral ureteral obstruction renal vein blood flow decreased significantly in obstructed kidneys from week 18 and thereafter. Good correlation was noted between MRI in vivo and in vitro kidney volume measurements (r = 0.972, p <0.001). CONCLUSIONS A significant increase in total volume and renal vein blood flow in contralateral nonobstructed kidneys did not develop immediately after the onset of detectable functional deterioration in partially obstructed kidneys. Therefore, caution should be used when incorporating compensatory growth into surgical decision making.
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Affiliation(s)
- J G Wen
- Institute of Experimental Clinical Research, Aarhus University, Denmark
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Abstract
Stereologic methods are used to obtain quantitative information about three-dimensional structures based on observations from section planes or--to a limited degree--projections. Stereologic methods, which are used in biologic research and especially in the research of normal and pathologic kidneys, will be discussed in this review. Special emphasis will be placed on modern stereologic methods, free of assumptions of the structure, size, and shape, etc., so-called UFAPP (unbiased for all practical purposes) stereologic methods. The basic foundation of all stereology, sampling, will be reviewed in relation to most of the methods discussed. Estimation of error variances and some of the basic problems in stereology will be reviewed briefly. Finally, a few comments will be made about the future directions for stereology in kidney research.
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Affiliation(s)
- J R Nyengaard
- Stereological Research Laboratory, University Institute of Pathology, University of Aarhus, Denmark.
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Ringgaard S, Christiansen T, Bak M, Pedersen EM, Stødkilde-Jørgensen H, Flyvbjerg A. Measurement of renal vein blood flow in rats by high-field magnetic resonance. Kidney Int 1997; 52:1359-63. [PMID: 9350659 DOI: 10.1038/ki.1997.461] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of the present study was to examine whether magnetic resonance imaging (MRI) based method for non-invasive in vivo measurement of vein blood flow in rats could be used to estimate renal blood flow (RBF). Measurements were performed using a high-field (7 Tesla) MRI scanner with a short echo time phase contrast velocity measurement pulse sequence. The method was evaluated in vitro by flow measurements in an acrylic pipe and in vivo by recording left renal vein blood flow in normal and unilaterally nephrectomized rats. In a subset of animals RBF was measured by a direct method using 14C-tetraethylammoniumbromide. In vitro a high accuracy was found between applied and MRI measured flow rates in the range from 0.5 to 33 ml/min (r = 0.997; P < 0.001). In vivo the MRI measured left renal vein blood flow was 70% higher in unilaterally nephrectomized animals compared to control animals (3.4 +/- 0.4 ml/min/ 100 g body wt vs. 2.0 +/- 0.1 ml/min/100 g body wt, P < 0.001). Direct measurements of RBF revealed comparable values (3.4 +/- 0.3 ml/min/100 g body wt vs. 2.3 +/- 0.4 ml/min/100 g body wt, P = 0.05). In addition, the left kidney volume was recorded by MRI with an increase amounting to 40% (1.18 +/- 0.05 ml vs. 0.84 +/- 0.02 ml; P < 0.001) in the nephrectomized group compared to controls. Finally, a positive correlation was seen between left renal vein blood flow and MRI measured renal volume (r = 0.91; P < 0.001). In summary, MRI is a non-invasive tool by which measurement of renal vein blood flow can be performed, and it is concluded that MRI-based renal vein flow measurements can be used to estimate RBF in small rodents.
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Affiliation(s)
- S Ringgaard
- Magnetic Resonance Research Centre, Aarhus University Hospital, Aarhus University, Denmark.
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