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van de Burgt A, van Velden FHP, Kwakkenbos K, Smit F, de Geus-Oei LF, Dekkers IA. Dynamic rubidium-82 PET/CT as a novel tool for quantifying hemodynamic differences in renal blood flow using a one-tissue compartment model. Med Phys 2024; 51:4069-4080. [PMID: 38709908 DOI: 10.1002/mp.17080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/01/2024] [Accepted: 04/04/2024] [Indexed: 05/08/2024] Open
Abstract
PURPOSE Assessing renal perfusion in-vivo is challenging and quantitative information regarding renal hemodynamics is hardly incorporated in medical decision-making while abnormal renal hemodynamics might play a crucial role in the onset and progression of renal disease. Combining physiological stimuli with rubidium-82 positron emission tomography/computed tomography (82Rb PET/CT) offers opportunities to test the kidney perfusion under various conditions. The aim of this study is: (1) to investigate the application of a one-tissue compartment model for measuring renal hemodynamics with dynamic 82Rb PET/CT imaging, and (2) to evaluate whether dynamic PET/CT is sensitive to detect differences in renal hemodynamics in stress conditions compared to resting state. METHODS A one-tissue compartment model for the kidney was applied to cardiac 82Rb PET/CT scans that were obtained for ischemia detection as part of clinical care. Retrospective data, collected from 17 patients undergoing dynamic myocardial 82Rb PET/CT imaging in rest, were used to evaluate various CT-based volumes of interest (VOIs) of the kidney. Subsequently, retrospective data, collected from 10 patients (five impaired kidney functions and five controls) undergoing dynamic myocardial 82Rb PET/CT imaging, were used to evaluate image-derived input functions (IDIFs), PET-based VOIs of the kidney, extraction fractions, and whether dynamic 82Rb PET/CT can measure renal hemodynamics differences using the renal blood flow (RBF) values in rest and after exposure to adenosine pharmacological stress. RESULTS The delivery rate (K1) values showed no significant (p = 0.14) difference between the mean standard deviation (SD) K1 values using one CT-based VOI and the use of two, three, and four CT-based VOIs, respectively 2.01(0.32), 1.90(0.40), 1.93(0.39), and 1.94(0.40) mL/min/mL. The ratio between RBF in rest and RBF in pharmacological stress for the controls were overall significantly lower compared to the impaired kidney function group for both PET-based delineation methods (region growing and iso-contouring), with the smallest median interquartile range (IQR) of 0.40(0.28-0.66) and 0.96(0.62-1.15), respectively (p < 0.05). The K1 of the impaired kidney function group were close to 1.0 mL/min/mL. CONCLUSIONS This study demonstrated that obtaining renal K1 and RBF values using 82Rb PET/CT was feasible using a one-tissue compartment model. Applying iso-contouring as the PET-based VOI of the kidney and using AA as an IDIF is suggested for consideration in further studies. Dynamic 82Rb PET/CT imaging showed significant differences in renal hemodynamics in rest compared to when exposed to adenosine. This indicates that dynamic 82Rb PET/CT has potential to detect differences in renal hemodynamics in stress conditions compared to the resting state, and might be useful as a novel diagnostic tool for assessing renal perfusion.
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Affiliation(s)
- Alina van de Burgt
- Department of Nuclear Medicine, Alrijne hospital, Leiderdorp, The Netherlands
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Koen Kwakkenbos
- Department of Nuclear Medicine, Alrijne hospital, Leiderdorp, The Netherlands
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Frits Smit
- Department of Nuclear Medicine, Alrijne hospital, Leiderdorp, The Netherlands
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Lioe-Fee de Geus-Oei
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
- Biomedical Photonic Imaging Group, University of Twente, Enschede, The Netherlands
- Department of Radiation Science & Technology, Delft University of Technology, Delft, The Netherlands
| | - Ilona A Dekkers
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
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Rasmussen CW, Bøgh N, Ringgaard S, Birn H, Vaeggemose M, Schulte RF, Laustsen C. Daytime Variation in Kidney Perfusion, Oxygenation, and Sodium Concentration Assessed by Multiparametric MRI in Healthy Volunteers. J Magn Reson Imaging 2024; 59:1603-1611. [PMID: 37656067 DOI: 10.1002/jmri.28983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/14/2023] [Accepted: 08/15/2023] [Indexed: 09/02/2023] Open
Abstract
BACKGROUND MRI can provide information on kidney structure, perfusion, and oxygenation. Furthermore, it allows for the assessment of kidney sodium concentrations and handling, allowing multiparametric evaluation of kidney physiology. Multiparametric MRI is promising for establishing prognosis and monitoring treatment responses in kidney diseases, but its intraindividual variation during the day is unresolved. PURPOSE To investigate the variation in multiparametric MRI measurements from the morning to the evening. STUDY TYPE Prospective. POPULATION Ten healthy volunteers, aged 29 ± 5 without history of kidney disease. FIELD STRENGTH/SEQUENCE 3 T/T1 mapping, blood-oxygen level dependent imaging, arterial spin labeling perfusion imaging, diffusion weighted imaging, and sodium imaging. ASSESSMENT A multiparametric MRI protocol, yielding T1, R2*, ADC, renal blood flow and renal sodium levels, was acquired in the morning, noon, and evening. The participants were fasting prior to the first examination. Urine biochemical analyses were performed to complement MRI data. The cortex and medulla were analyzed separately in a semi-automatic fashion, and gradients of total sodium concentration (TSC) and R2* gradients were calculated from outer cortex to inner medulla. STATISTICAL TEST Analyses of variance and mixed-effects models to estimate differences from time of day. Coefficients of variation to assess variability within and between participants. A P-value <0.05 was considered statistically significant. RESULTS The coefficients of variation varied from 5% to 18% for proton-based parametric sequences, while it was 38% for TSC over a day. DATA CONCLUSION Multiparametric MRI is stable over the day. The coefficients of variation over a day were lower for proton multiparametric MRI, but higher for sodium MRI. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Camilla W Rasmussen
- The MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Nikolaj Bøgh
- The MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Steffen Ringgaard
- The MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Henrik Birn
- Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Michael Vaeggemose
- The MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- GE HealthCare, Broendby, Denmark
| | | | - Christoffer Laustsen
- The MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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Alhummiany B, Sharma K, Buckley DL, Soe KK, Sourbron SP. Physiological confounders of renal blood flow measurement. MAGMA (NEW YORK, N.Y.) 2023:10.1007/s10334-023-01126-7. [PMID: 37971557 DOI: 10.1007/s10334-023-01126-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/26/2023] [Accepted: 10/12/2023] [Indexed: 11/19/2023]
Abstract
OBJECTIVES Renal blood flow (RBF) is controlled by a number of physiological factors that can contribute to the variability of its measurement. The purpose of this review is to assess the changes in RBF in response to a wide range of physiological confounders and derive practical recommendations on patient preparation and interpretation of RBF measurements with MRI. METHODS A comprehensive search was conducted to include articles reporting on physiological variations of renal perfusion, blood and/or plasma flow in healthy humans. RESULTS A total of 24 potential confounders were identified from the literature search and categorized into non-modifiable and modifiable factors. The non-modifiable factors include variables related to the demographics of a population (e.g. age, sex, and race) which cannot be manipulated but should be considered when interpreting RBF values between subjects. The modifiable factors include different activities (e.g. food/fluid intake, exercise training and medication use) that can be standardized in the study design. For each of the modifiable factors, evidence-based recommendations are provided to control for them in an RBF-measurement. CONCLUSION Future studies aiming to measure RBF are encouraged to follow a rigorous study design, that takes into account these recommendations for controlling the factors that can influence RBF results.
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Affiliation(s)
- Bashair Alhummiany
- Department of Biomedical Imaging Sciences, University of Leeds, Leeds, LS2 9NL, UK.
| | - Kanishka Sharma
- Department of Imaging, Infection, Immunity and Cardiovascular Disease, The University of Sheffield, Sheffield, UK
| | - David L Buckley
- Department of Biomedical Imaging Sciences, University of Leeds, Leeds, LS2 9NL, UK
| | - Kywe Kywe Soe
- Department of Imaging, Infection, Immunity and Cardiovascular Disease, The University of Sheffield, Sheffield, UK
| | - Steven P Sourbron
- Department of Imaging, Infection, Immunity and Cardiovascular Disease, The University of Sheffield, Sheffield, UK.
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Luther T, Eckerbom P, Cox E, Lipcsey M, Bülow S, Hultström M, Torrente FM, Weis J, Palm F, Francis S, Frithiof R, Liss P. Decreased renal perfusion during acute kidney injury in critical COVID-19 assessed by magnetic resonance imaging: a prospective case control study. Crit Care 2022; 26:262. [PMID: 36050748 PMCID: PMC9434518 DOI: 10.1186/s13054-022-04132-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/19/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Renal hypoperfusion has been suggested to contribute to the development of acute kidney injury (AKI) in critical COVID-19. However, limited data exist to support this. We aim to investigate the differences in renal perfusion, oxygenation and water diffusion using multiparametric magnetic resonance imaging in critically ill COVID-19 patients with and without AKI. METHODS A prospective case-control study where patients without prior kidney disease treated in intensive care for respiratory failure due to COVID-19 were examined. Kidney Disease: Improving Global Outcomes Creatinine criteria were used for group allocation. Main comparisons were tested using Mann-Whitney U test. RESULTS Nineteen patients were examined, ten with AKI and nine without AKI. Patients with AKI were examined in median 1 [0-2] day after criteria fulfillment. Age and baseline Plasma-Creatinine were similar in both groups. Total renal blood flow was lower in patients with AKI compared with patients without (median 645 quartile range [423-753] vs. 859 [746-920] ml/min, p = 0.037). Regional perfusion was reduced in both cortex (76 [51-112] vs. 146 [123-169] ml/100 g/min, p = 0.015) and medulla (28 [18-47] vs. 47 [38-73] ml/100 g/min, p = 0.03). Renal venous saturation was similar in both groups (72% [64-75] vs. 72% [63-84], ns.), as was regional oxygenation (R2*) in cortex (17 [16-19] vs. 17 [16-18] 1/s, ns.) and medulla (29 [24-39] vs. 27 [23-29] 1/s, ns.). CONCLUSIONS In critically ill COVID-19 patients with AKI, the total, cortical and medullary renal blood flows were reduced compared with similar patients without AKI, whereas no differences in renal oxygenation were demonstrable in this setting. Trial registration ClinicalTrials ID: NCT02765191 , registered May 6 2014 and updated May 7 2020.
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Affiliation(s)
- Tomas Luther
- Anaesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University Hospital, Uppsala University, 751 85, Uppsala, Sweden.
| | - Per Eckerbom
- Section of Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Eleanor Cox
- Sir Peter Mansfield Imaging Centre, School of Physics & Astronomy, University of Nottingham, Nottingham, UK
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Miklos Lipcsey
- Anaesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University Hospital, Uppsala University, 751 85, Uppsala, Sweden
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Sara Bülow
- Anaesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University Hospital, Uppsala University, 751 85, Uppsala, Sweden
| | - Michael Hultström
- Anaesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University Hospital, Uppsala University, 751 85, Uppsala, Sweden
- Integrative Physiology, Department Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Francisco Martinez Torrente
- Anaesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University Hospital, Uppsala University, 751 85, Uppsala, Sweden
| | - Jan Weis
- Department of Medical Physics, Uppsala University Hospital, Uppsala, Sweden
| | - Fredrik Palm
- Integrative Physiology, Department Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Susan Francis
- Sir Peter Mansfield Imaging Centre, School of Physics & Astronomy, University of Nottingham, Nottingham, UK
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - Robert Frithiof
- Anaesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University Hospital, Uppsala University, 751 85, Uppsala, Sweden
| | - Per Liss
- Section of Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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Kawakami S, Yasuno T, Kawakami S, Ito A, Fujimi K, Matsuda T, Nakashima S, Masutani K, Uehara Y, Higaki Y, Michishita R. The moderate-intensity continuous exercise maintains renal blood flow and does not impair the renal function. Physiol Rep 2022; 10:e15420. [PMID: 35924347 PMCID: PMC9350468 DOI: 10.14814/phy2.15420] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 12/30/2022] Open
Abstract
Exercise is restricted for individuals with reduced renal function because exercising reduces blood flow to the kidneys. Safe and effective exercise programs for individuals with reduced renal function have not yet been developed. We previously examined the relationship between exercise intensity and renal blood flow (RBF), revealing that moderate-intensity exercise did not reduce RBF. Determining the effects of exercise duration on RBF may have valuable clinical applications. The current study examined the effects of a single bout of continuous exercise at lactate threshold (LT) intensity on renal hemodynamics. Eight adult males participated in this study. Participants underwent 30 min of aerobic exercise at LT intensity using a cycle ergometer. Evaluation of renal hemodynamics was performed before and after exercise, in the recovery phase using ultrasound echo. Furthermore, blood and urine samplings were conducted before and after exercise, in the recovery phase. Compared with resting, RBF was not significantly changed immediately after continuous exercise (319 ± 102 vs. 308 ± 79 ml/min; p = 0.976) and exhibited no significant changes in the recovery phase. Moreover, urinary kidney injury molecule-1 (uKIM-1) level exhibited no significant change immediately after continuous exercise (0.52 ± 0.20 vs. 0.46 ± 0.27 μg/g creatinine; p = 0.447). In addition, the results revealed no significant change in urinary uKIM-1 in 60-min after exercise. Other renal injury biomarkers exhibited a similar pattern. These findings indicate that a single bout of moderate-intensity continuous exercise maintains RBF and does not induce renal injury.
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Affiliation(s)
- Shotaro Kawakami
- Graduate School of Sports and Health ScienceFukuoka UniversityFukuokaJapan
- Faculty of Sports and Health ScienceFukuoka UniversityFukuokaJapan
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
| | - Tetsuhiko Yasuno
- Division of Nephrology and Rheumatology, Department of Internal MedicineFukuoka University School of MedicineFukuokaJapan
| | - Saki Kawakami
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
| | - Ai Ito
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
| | - Kanta Fujimi
- Department of RehabilitationFukuoka University HospitalFukuokaJapan
| | - Takuro Matsuda
- Department of RehabilitationFukuoka University HospitalFukuokaJapan
| | - Shihoko Nakashima
- Faculty of Sports and Health ScienceFukuoka UniversityFukuokaJapan
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
| | - Kosuke Masutani
- Division of Nephrology and Rheumatology, Department of Internal MedicineFukuoka University School of MedicineFukuokaJapan
| | - Yoshinari Uehara
- Faculty of Sports and Health ScienceFukuoka UniversityFukuokaJapan
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
| | - Yasuki Higaki
- Faculty of Sports and Health ScienceFukuoka UniversityFukuokaJapan
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
| | - Ryoma Michishita
- Faculty of Sports and Health ScienceFukuoka UniversityFukuokaJapan
- The Fukuoka University Institute for Physical ActivityFukuokaJapan
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Reference Intervals of Spot Urine Creatinine-to-Osmolality Ratio as a Surrogate of Urinary Creatinine Excretion Rate. DISEASE MARKERS 2022; 2022:3549047. [PMID: 35923243 PMCID: PMC9343203 DOI: 10.1155/2022/3549047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/22/2022] [Accepted: 07/07/2022] [Indexed: 11/17/2022]
Abstract
A spot urine creatinine-to-osmolality ratio (sUCr/Osm) is proposed as a surrogate of the urinary excretion rate of creatinine (Cr) and convenient for forecasting serum Cr (SCr) trends. The lower the sUCr/Osm, the lower the excreted Cr amount accompanied by per unit of osmoles, the higher the risk of Cr accumulation. For exploring the reference intervals of sUCr/Osm in general adults, a cross-sectional analysis was performed on a subset of data from the National Health and Nutrition Examination Survey (NHANES) 2011–2012. Of the eligible 3,316 adults aged 18.0 to 79.9 years, the age (mean ± SD) was 45.2 ± 17.2 years old, women was 45.02%, body weight (BW) was 76.1 ± 14.5 kg, and African Americans was 23.6%. Blood urea nitrogen (BUN) was 12.6 ± 4.7 mg/dL; SCr was 0.89 ± 0.34 mg/dL. As spot urine Cr and osmolality were 127.1 ± 84.0 mg/dl and 649 ± 266 mOsm/kg, respectively, sUCr/Osm was 0.19 ± 0.08. With adjustment of factors related to personal urinary excretion of Cr and osmoles by multivariable regression analysis, the estimated sUCr/Osm (esUCr/Osm) for an individual was 0.153 × (age in year)−0.070 × (BW in kg)0.283 × 1.244 [if African American] × (BUN in mg/dL)−0.310 × (SCr in mg/dL)0.681. The index of sUCr/Osm to personalized esUCr/Osm was 1.05 ± 0.39. When only low urinary excretion of Cr is likely to be of clinical concern, further analysis showed 157 individuals (4.7%, outside the 5th percentile) had their original sUCr/Osm < 0.08; 157 had the sUCr/Osm indexed for personalized esUCr/Osm < 0.50.
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Kroetsch JT, Lidington D, Bolz SS. The emerging significance of circadian rhythmicity in microvascular resistance. Chronobiol Int 2021; 39:465-475. [PMID: 34915783 DOI: 10.1080/07420528.2021.2009505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The Earth's rotation generates environmental oscillations (e.g., in light and temperature) that have imposed unique evolutionary pressures over millions of years. Consequently, the circadian clock, a ubiquitously expressed molecular system that aligns cellular function to these environmental cues, has become an integral component of our physiology. The resulting functional rhythms optimize and economize physiological performance: perturbing these rhythms, therefore, is frequently deleterious. This perspective article focuses on circadian rhythms in resistance artery myogenic reactivity, a key mechanism governing tissue perfusion, total peripheral resistance and systemic blood pressure. Emerging evidence suggests that myogenic reactivity rhythms are locally generated in a microvascular bed-specific manner at the level of smooth muscle cells. This implies that there is a distinct interface between the molecular clock and the signalling pathways underlying myogenic reactivity in the microvascular beds of different organs. By understanding the precise nature of these molecular links, it may become possible to therapeutically manipulate microvascular tone in an organ-specific manner. This raises the prospect that interventions for vascular pathologies that are challenging to treat, such as hypertension and brain malperfusion, can be significantly improved.
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Affiliation(s)
- Jeffrey T Kroetsch
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Toronto Centre for Microvascular Medicine at the Ted Rogers Centre for Heart Research Translational Biology and Engineering Program, University of Toronto, Ontario, Canada
| | - Darcy Lidington
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Toronto Centre for Microvascular Medicine at the Ted Rogers Centre for Heart Research Translational Biology and Engineering Program, University of Toronto, Ontario, Canada
| | - Steffen-Sebastian Bolz
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Toronto Centre for Microvascular Medicine at the Ted Rogers Centre for Heart Research Translational Biology and Engineering Program, University of Toronto, Ontario, Canada.,Heart & Stroke/Richard Lewar Centre of Excellence for Cardiovascular Research, University of Toronto, Toronto, Ontario, Canada
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Laursen JC, Søndergaard-Heinrich N, de Melo JML, Haddock B, Rasmussen IKB, Safavimanesh F, Hansen CS, Størling J, Larsson HBW, Groop PH, Frimodt-Møller M, Andersen UB, Rossing P. Acute effects of dapagliflozin on renal oxygenation and perfusion in type 1 diabetes with albuminuria: A randomised, double-blind, placebo-controlled crossover trial. EClinicalMedicine 2021; 37:100895. [PMID: 34386735 PMCID: PMC8343250 DOI: 10.1016/j.eclinm.2021.100895] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Inhibitors of the sodium-glucose cotransporter 2 (SGLT2) slow the progression of diabetic kidney disease, possibly by reducing the proximal tubule transport workload with subsequent improvement of renal oxygenation. We aimed to test this hypothesis in individuals with type 1 diabetes and albuminuria. METHODS A randomised, double-blind, placebo-controlled, crossover trial with a single 50 mg dose of the SGLT2 inhibitor dapagliflozin and placebo in random order, separated by a two-week washout period. Magnetic resonance imaging (MRI) was used to assess renal R2* (a low value corresponds to a high tissue oxygenation), renal perfusion (arterial spin labelling) and renal artery flow (phase contrast imaging) at baseline, three- and six hours from tablet ingestion. Exploratory outcomes, including baroreflex sensitivity, peripheral blood oxygen saturation, peripheral blood mononuclear cell mitochondrial oxygen consumption rate, and biomarkers of inflammation were evaluated at baseline and 12 h from medication. The study is registered in the EU Clinical Trials Register (EudraCT 2019-004,557-92), on ClinicalTrials.gov (NCT04193566), and is completed. FINDINGS Between February 3, 2020 and October 23, 2020, 31 individuals were screened, and 19 eligible individuals were randomised. Three dropped out before receiving any of the interventions and one dropped out after receiving only placebo. We included 15 individuals (33% female) in the per-protocol analysis with a mean age of 58 (SD 14) years, median urinary albumin creatinine ratio of 46 [IQR 21-58] mg/g and an eGFR of 73 (32) ml/min/1·73m2. The mean changes in renal cortical R2* from baseline to six hours were for dapagliflozin -1·1 (SD 0·7) s-1 and for placebo +1·3 (0·7) s-1, resulting in a difference between interventions of -2·3 s-1 [95% CI -4·0 to -0·6]; p = 0·012. No between-intervention differences were found in any other MRI outcomes, physiological parameters or exploratory outcomes. There were no adverse events. INTERPRETATION A single dose of 50 mg dapagliflozin acutely improved renal cortical R2* without changing renal perfusion or blood flow. This suggests improved renal cortical oxygenation due to a reduced tubular transport workload in the proximal tubules. Such improved oxygenation may in part explain the long-term beneficial renal effects seen with SGLT2 inhibitors, but it remains to be determined whether the observed effects can be achieved with lower doses, with chronic treatment and if they occur in type 2 diabetes as well.
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Affiliation(s)
| | | | | | - Bryan Haddock
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Copenhagen University Hospital, Denmark
| | | | | | | | | | - Henrik Bo Wiberg Larsson
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Copenhagen University Hospital, Denmark
| | - Per-Henrik Groop
- Folkhälsan Research Center, Helsinki, Finland
- Department of Nephrology, University of Helsinki and Helsinki University Hospital, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Finland
- Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia
| | | | - Ulrik Bjørn Andersen
- Steno Diabetes Center Copenhagen, Denmark
- University of Copenhagen, Denmark
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Copenhagen University Hospital, Denmark
- Folkhälsan Research Center, Helsinki, Finland
- Department of Nephrology, University of Helsinki and Helsinki University Hospital, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, Finland
- Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia
| | - Peter Rossing
- Steno Diabetes Center Copenhagen, Denmark
- University of Copenhagen, Denmark
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Applications of cosinor rhythmometry in pharmacology. J Pharmacokinet Pharmacodyn 2021; 48:339-359. [PMID: 33755872 DOI: 10.1007/s10928-021-09748-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/04/2021] [Indexed: 10/21/2022]
Abstract
Study design and data analysis are two important aspects relevant to chronopharmacometrics. Blunders can be avoided by recognizing that most physiological variables are circadian periodic. Both ill health and treatment can affect the amplitude, phase, and/or period of circadian (and other) rhythms, in addition to their mean. The involvement of clock genes in molecular pathways related to important physiological systems underlies the bidirectional relationship often seen between circadian rhythm disruption and disease risk. Circadian rhythm characteristics of marker rhythms interpreted in the light of chronobiologic reference values represent important diagnostic tools. A set of cosinor-related programs is presented. They include the least squares fit of multiple-frequency cosine functions to model the time structure of individual records; a cosinor-based spectral analysis to detect periodic signals; the population-mean cosinor to generalize inferences; the chronobiologic serial section to follow the time course of changing rhythm parameters over time; and parameter tests to assess differences among populations. Relative merits of other available cosinor and non-parametric algorithms are reviewed. Parameter tests to compare individual records and a self-starting cumulative sum (CUSUM) make personalized chronotherapy possible, where the treatment of each patient relies on an N-of-1 design. Methods are illustrated in a few examples relevant to endocrinology, cancer and cardiology. New sensing technology yielding large personal data sets is likely to change the healthcare system. Chronobiologic concepts and methods should become an integral part of these evolving systems.
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