1
|
Gumz ML, Shimbo D, Abdalla M, Balijepalli RC, Benedict C, Chen Y, Earnest DJ, Gamble KL, Garrison SR, Gong MC, Hogenesch JB, Hong Y, Ivy JR, Joe B, Laposky AD, Liang M, MacLaughlin EJ, Martino TA, Pollock DM, Redline S, Rogers A, Dan Rudic R, Schernhammer ES, Stergiou GS, St-Onge MP, Wang X, Wright J, Oh YS. Toward Precision Medicine: Circadian Rhythm of Blood Pressure and Chronotherapy for Hypertension - 2021 NHLBI Workshop Report. Hypertension 2023; 80:503-522. [PMID: 36448463 PMCID: PMC9931676 DOI: 10.1161/hypertensionaha.122.19372] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Healthy individuals exhibit blood pressure variation over a 24-hour period with higher blood pressure during wakefulness and lower blood pressure during sleep. Loss or disruption of the blood pressure circadian rhythm has been linked to adverse health outcomes, for example, cardiovascular disease, dementia, and chronic kidney disease. However, the current diagnostic and therapeutic approaches lack sufficient attention to the circadian rhythmicity of blood pressure. Sleep patterns, hormone release, eating habits, digestion, body temperature, renal and cardiovascular function, and other important host functions as well as gut microbiota exhibit circadian rhythms, and influence circadian rhythms of blood pressure. Potential benefits of nonpharmacologic interventions such as meal timing, and pharmacologic chronotherapeutic interventions, such as the bedtime administration of antihypertensive medications, have recently been suggested in some studies. However, the mechanisms underlying circadian rhythm-mediated blood pressure regulation and the efficacy of chronotherapy in hypertension remain unclear. This review summarizes the results of the National Heart, Lung, and Blood Institute workshop convened on October 27 to 29, 2021 to assess knowledge gaps and research opportunities in the study of circadian rhythm of blood pressure and chronotherapy for hypertension.
Collapse
Affiliation(s)
- Michelle L Gumz
- Department of Physiology and Aging; Center for Integrative Cardiovascular and Metabolic Disease, Department of Medicine, Division of Nephrology, Hypertension and Renal Transplantation, University of Florida, Gainesville, FL (M.L.G.)
| | - Daichi Shimbo
- Department of Medicine, The Columbia Hypertension Center, Columbia University Irving Medical Center, New York, NY (D.S.)
| | - Marwah Abdalla
- Department of Medicine, Center for Behavioral Cardiovascular Health, Columbia University Irving Medical Center, New York, NY (M.A.)
| | - Ravi C Balijepalli
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| | - Christian Benedict
- Department of Pharmaceutical Biosciences, Molecular Neuropharmacology, Uppsala University, Sweden (C.B.)
| | - Yabing Chen
- Department of Pathology, University of Alabama at Birmingham, and Research Department, Birmingham VA Medical Center, AL (Y.C.)
| | - David J Earnest
- Department of Neuroscience & Experimental Therapeutics, Texas A&M University, Bryan, TX (D.J.E.)
| | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, AL (K.L.G.)
| | - Scott R Garrison
- Department of Family Medicine, University of Alberta, Canada (S.R.G.)
| | - Ming C Gong
- Department of Physiology, University of Kentucky, Lexington, KY (M.C.G.)
| | | | - Yuling Hong
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| | - Jessica R Ivy
- University/British Heart Foundation Centre for Cardiovascular Science, The Queen's Medical Research Institute, The University of Edinburgh, United Kingdom (J.R.I.)
| | - Bina Joe
- Department of Physiology and Pharmacology and Center for Hypertension and Precision Medicine, University of Toledo College of Medicine and Life Sciences, OH (B.J.)
| | - Aaron D Laposky
- National Center on Sleep Disorders Research, Division of Lung Diseases, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (A.D.L.)
| | - Mingyu Liang
- Center of Systems Molecular Medicine, Department of Physiology, Medical College of Wisconsin, Milwaukee, WI (M.L.)
| | - Eric J MacLaughlin
- Department of Pharmacy Practice, Texas Tech University Health Sciences Center, Amarillo, TX (E.J.M.)
| | - Tami A Martino
- Center for Cardiovascular Investigations, Department of Biomedical Sciences, University of Guelph, Ontario, Canada (T.A.M.)
| | - David M Pollock
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, AL (D.M.P.)
| | - Susan Redline
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (S.R.)
| | - Amy Rogers
- Division of Molecular and Clinical Medicine, University of Dundee, United Kingdom (A.R.)
| | - R Dan Rudic
- Department of Pharmacology and Toxicology, Augusta University, GA (R.D.R.)
| | - Eva S Schernhammer
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (E.S.S.)
| | - George S Stergiou
- Hypertension Center, STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece (G.S.S.)
| | - Marie-Pierre St-Onge
- Division of General Medicine, Department of Medicine, Columbia University Irving Medical Center' New York, NY (M.-P.S.-O.)
| | - Xiaoling Wang
- Georgia Prevention Institute, Department of Medicine, Augusta University, GA (X.W.)
| | - Jacqueline Wright
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| | - Young S Oh
- Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD (R.C.B., Y.H., J.W., Y.S.O.)
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Tawfik MK, Keshawy MM, Makary S. Blocking angiotensin 2 receptor attenuates diabetic nephropathy via mitigating ANGPTL2/TL4/NF-κB expression. Mol Biol Rep 2021; 48:6457-6470. [PMID: 34431038 DOI: 10.1007/s11033-021-06647-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 08/11/2021] [Indexed: 01/13/2023]
Abstract
BACKGROUND Diabetic nephropathy (DN) is a consequence of diabetes mellitus (DM) and is associated with early changes in renal angiotensin II (ANG II). These changes were evaluated using ANG II blocker valsartan early from week two of diabetes (experiment I, renoprotective) and late from week nine of diabetes (experiment II, renotherapeutic) to the end of both experiments at week twelve. METHODS AND RESULTS In both experiments, adult male Wister rats were divided into (i) vehicle group; (ii) valsartan received oral 30 mg/Kg/day; (iii) diabetic received single 50 mg/Kg intraperitoneal streptozotocin injection; (iv) renoprotection, diabetic rats received valsartan treated in experiments I and II. DM effects on urine albumin excretion, blood pressure, and renal ANG II were measured. Urinary nephrin, kidney injury molecule-1 (KIM-1), renal angiopoietin-like protein 2 (ANGPTL2), and toll-like receptor 4 (TLR 4) mRNA expression were tested. DM-initiated fibrotic markers integrin, α-smooth muscle actin expression, and collagen IV and apoptotic protein caspase 3 were tested. DM induced early changes starting from week four in the tested variables. At week twelve, in both experiments, valsartan intervention showed a significant reduction in ANG II, ANGPTL2, TLR 4 and integrin expression and improvement in albuminuria, blood pressure, urinary biomarkers, fibrotic and apoptotic markers. CONCLUSIONS Changes leading to DN starts early in the disease course and ANG II reduction decreased the expression of ANGPTL2 and integrin which preserve the glomerular barrier. Blocking ANG II was able to decrease TLR 4 and inflammatory cytokines leading to decreasing DN.
Collapse
Affiliation(s)
- Mona K Tawfik
- Department of Pharmacology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Mohammed M Keshawy
- Nephrology Division, Department of Internal Medicine, Faculty of Medicine, Suez Canal University, Ismailia, 41522, Egypt.
| | - Samy Makary
- Department of Physiology, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| |
Collapse
|
4
|
Circadian variations of vasoconstriction and blood pressure in physiology and diabetes. Curr Opin Pharmacol 2021; 57:125-131. [PMID: 33721615 DOI: 10.1016/j.coph.2021.02.001] [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: 09/27/2020] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 01/14/2023]
Abstract
The intrinsic vascular smooth muscle contraction and vasoconstriction show time-of-day variations, contributing to the blood pressure circadian rhythm, which is essential for cardiovascular health. This brief review provides an overview of our current understanding of the mechanisms underlying the time-of-day variations of vascular smooth muscle contraction. We discuss the potential contribution of the time-of-day variations of vasoconstriction to the physiological blood pressure circadian rhythm. Finally, we survey the data obtained in the type 2 diabetic db/db mouse model that demonstrate the alterations of the time-of-day variations of vasoconstriction and the nondipping blood pressure in diabetes.
Collapse
|
5
|
Beck L, Pinilla E, Arcanjo DDR, Hernanz R, Prat-Duran J, Petersen AG, Köhler R, Sheykhzade M, Comerma-Steffensen S, Simonsen U. Pirfenidone Is a Vasodilator: Involvement of K V7 Channels in the Effect on Endothelium-Dependent Vasodilatation in Type-2 Diabetic Mice. Front Pharmacol 2021; 11:619152. [PMID: 33643042 PMCID: PMC7906977 DOI: 10.3389/fphar.2020.619152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/30/2020] [Indexed: 12/27/2022] Open
Abstract
Endothelial cell dysfunction and fibrosis are associated with worsening of the prognosis in patients with cardiovascular disease. Pirfenidone has a direct antifibrotic effect, but vasodilatation may also contribute to the effects of pirfenidone. Therefore, in a first study we investigated the mechanisms involved in the relaxant effect of pirfenidone in rat intrapulmonary arteries and coronary arteries from normal mice. Then in a second study, we investigated whether pirfenidone restores endothelial function in the aorta and mesenteric arteries from diabetic animals. From 16–18-week old normal male C57BL/6 mice and normoglycemic (db/db+), and type 2 diabetic (db/db) male and female mice, arteries were mounted in microvascular isometric myographs for functional studies, and immunoblotting was performed. In rat pulmonary arteries and mouse coronary arteries, pirfenidone induced relaxations, which were inhibited in preparations without endothelium. In mouse coronary arteries, pirfenidone relaxation was inhibited in the presence of a nitric oxide (NO) synthase inhibitor, NG-nitro-l-arginine (L-NOARG), a blocker of large-conductance calcium-activated potassium channels (BKCa), iberiotoxin, and a blocker of KV7 channels, XE991. Patch clamp studies in vascular smooth muscle revealed pirfenidone increased iberiotoxin-sensitive current. In the aorta and mesenteric small arteries from diabetic db/db mice relaxations induced by the endothelium-dependent vasodilator, acetylcholine, were markedly reduced compared to db/db + mice. Pirfenidone enhanced the relaxations induced by acetylcholine in the aorta from diabetic male and female db/db mice. An opener of KV7 channels, flupirtine, had the same effect as pirfenidone. XE991 reduced the effect of pirfenidone and flupirtine and further reduced acetylcholine relaxations in the aorta. In the presence of iberiotoxin, pirfenidone still increased acetylcholine relaxation in aorta from db/db mice. Immunoblotting for KV7.4, KV7.5, and BKCa channel subunits were unaltered in aorta from db/db mice. Pirfenidone failed to improve acetylcholine relaxation in mesenteric arteries, and neither changed acetylcholine-induced transient decreases in blood pressure in db/db+ and db/db mice. In conclusion, pirfenidone vasodilates pulmonary and coronary arteries. In coronary arteries from normal mice, pirfenidone induces NO-dependent vasodilatation involving BKCa and KV7 channels. Pirfenidone improves endothelium-dependent vasodilatation in aorta from diabetic animals by a mechanism involving voltage-gated KV7 channels, a mechanism that may contribute to the antifibrotic effect of pirfenidone.
Collapse
Affiliation(s)
- Lilliana Beck
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Estéfano Pinilla
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Department of Physiology, Faculty of Pharmacy, Universidad Complutense, Madrid, Spain
| | - Daniel Dias Rufino Arcanjo
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Department of Biophysics and Physiology, Laboratory of Functional and Molecular Studies in Physiopharmacology, Federal University of Piauí, Teresina, Brazil
| | - Raquel Hernanz
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, Alcorcón, Spain
| | - Judit Prat-Duran
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Asbjørn Graver Petersen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Ralf Köhler
- Aragón Agency for Research and Development (ARAID), Zaragoza, Spain
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark.,Department of Biomedical Sciences/Animal Physiology, Faculty of Veterinary, Central University of Venezuela, Maracay, Venezuela
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| |
Collapse
|
6
|
Beck L, Su J, Comerma-Steffensen S, Pinilla E, Carlsson R, Hernanz R, Sheykhzade M, Danielsen CC, Simonsen U. Endothelial Dysfunction and Passive Changes in the Aorta and Coronary Arteries of Diabetic db/db Mice. Front Physiol 2020; 11:667. [PMID: 32655412 PMCID: PMC7324802 DOI: 10.3389/fphys.2020.00667] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 05/25/2020] [Indexed: 12/19/2022] Open
Abstract
Endothelial cell dysfunction and vessel stiffening are associated with a worsened prognosis in diabetic patients with cardiovascular diseases. The present study hypothesized that sex impacts endothelial dysfunction and structural changes in arteries from diabetic mice. In diabetic (db/db) and normoglycaemic (db/db+) mice, the mechanical properties were investigated in pressurized isolated left anterior descending coronary arteries and aorta segments that were subjected to tensile testing. Functional studies were performed on wire-mounted vascular segments. The male and female db/db mice were hyperglycaemic and had markedly increased body weight. In isolated aorta segments without the contribution of smooth muscle cells, load to rupture, viscoelasticity, and collagen content were decreased suggesting larger distensibility of the arterial wall in both male and female db/db mice. In male db/db aorta segments with smooth muscle cell contribution, lumen diameter was smaller and the passive stretch-tension curve was leftward-shifted, while they were unaltered in female db/db aorta segments versus control db/db+ mice. In contrast to female db/db mice, coronary arteries from male db/db mice had altered stress-strain relationships and increased distensibility. Transthoracic echocardiography revealed a dilated left ventricle with unaltered cardiac output, while aortic flow velocity was decreased in male db/db mice. Impairment of acetylcholine relaxation was aggravated in aorta from female db/db compared to control and male db/db mice, while impairment of sodium nitroprusside relaxations was only observed in aorta from male db/db mice. The remodeling in the coronary arteries and aorta suggests an adaptation of the arterial wall to the reduced flow velocity with sex-specific differences in the passive properties of aorta and coronary arteries. The findings of less distensible arteries and more pronounced endothelial dysfunction in female compared to male diabetic mice may have implications for the observed higher incidence of macrovascular complications in diabetic women.
Collapse
Affiliation(s)
- Lilliana Beck
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark
| | - Junjing Su
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark
| | - Simon Comerma-Steffensen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark.,Department of Biomedical Sciences/Animal Physiology, Veterinary Faculty, Central University of Venezuela, Maracay, Venezuela
| | - Estéfano Pinilla
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark
| | - Rune Carlsson
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark
| | - Raquel Hernanz
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark.,Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, Alcorcón, Spain
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Carl Christian Danielsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, Faculty of Health Aarhus University, Aarhus, Denmark
| |
Collapse
|
7
|
Vallon V, Unwin R, Inscho EW, Leipziger J, Kishore BK. Extracellular Nucleotides and P2 Receptors in Renal Function. Physiol Rev 2019; 100:211-269. [PMID: 31437091 DOI: 10.1152/physrev.00038.2018] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The understanding of the nucleotide/P2 receptor system in the regulation of renal hemodynamics and transport function has grown exponentially over the last 20 yr. This review attempts to integrate the available data while also identifying areas of missing information. First, the determinants of nucleotide concentrations in the interstitial and tubular fluids of the kidney are described, including mechanisms of cellular release of nucleotides and their extracellular breakdown. Then the renal cell membrane expression of P2X and P2Y receptors is discussed in the context of their effects on renal vascular and tubular functions. Attention is paid to effects on the cortical vasculature and intraglomerular structures, autoregulation of renal blood flow, tubuloglomerular feedback, and the control of medullary blood flow. The role of the nucleotide/P2 receptor system in the autocrine/paracrine regulation of sodium and fluid transport in the tubular and collecting duct system is outlined together with its role in integrative sodium and fluid homeostasis and blood pressure control. The final section summarizes the rapidly growing evidence indicating a prominent role of the extracellular nucleotide/P2 receptor system in the pathophysiology of the kidney and aims to identify potential therapeutic opportunities, including hypertension, lithium-induced nephropathy, polycystic kidney disease, and kidney inflammation. We are only beginning to unravel the distinct physiological and pathophysiological influences of the extracellular nucleotide/P2 receptor system and the associated therapeutic perspectives.
Collapse
Affiliation(s)
- Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Robert Unwin
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Edward W Inscho
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Jens Leipziger
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Bellamkonda K Kishore
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| |
Collapse
|
8
|
Mathematical model of hemodynamic mechanisms and consequences of glomerular hypertension in diabetic mice. NPJ Syst Biol Appl 2018; 5:2. [PMID: 30564457 PMCID: PMC6288095 DOI: 10.1038/s41540-018-0077-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 06/29/2018] [Accepted: 10/22/2018] [Indexed: 12/12/2022] Open
Abstract
Many preclinically promising therapies for diabetic kidney disease fail to provide efficacy in humans, reflecting limited quantitative translational understanding between rodent models and human disease. To quantitatively bridge interspecies differences, we adapted a mathematical model of renal function from human to mice, and incorporated adaptive and pathological mechanisms of diabetes and nephrectomy to describe experimentally observed changes in glomerular filtration rate (GFR) and proteinuria in db/db and db/db UNX (uninephrectomy) mouse models. Changing a small number of parameters, the model reproduced interspecies differences in renal function. Accounting for glucose and Na+ reabsorption through sodium glucose cotransporter 2 (SGLT2), increasing blood glucose and Na+ intake from normal to db/db levels mathematically reproduced glomerular hyperfiltration observed experimentally in db/db mice. This resulted from increased proximal tubule sodium reabsorption, which elevated glomerular capillary hydrostatic pressure (Pgc) in order to restore sodium balance through increased GFR. Incorporating adaptive and injurious effects of elevated Pgc, we showed that preglomerular arteriole hypertrophy allowed more direct transmission of pressure to the glomerulus with a smaller mean arterial pressure rise; Glomerular hypertrophy allowed a higher GFR for a given Pgc; and Pgc-driven glomerulosclerosis and nephron loss reduced GFR over time, while further increasing Pgc and causing moderate proteinuria, in agreement with experimental data. UNX imposed on diabetes increased Pgc further, causing faster GFR decline and extensive proteinuria, also in agreement with experimental data. The model provides a mechanistic explanation for hyperfiltration and proteinuria progression that will facilitate translation of efficacy for novel therapies from mouse models to human. Many drugs for diabetic kidney disease appear to work in rodents, but fail in humans, reflecting incomplete understanding of disease processes. A team led by Melissa Hallow at the University of Georgia has developed a mathematical model that explains how elevated blood glucose in diabetes causes kidney injury in mice. They first showed that normal human, rat, or mouse kidney physiology could be reproduced with the same model by changing a small number of parameters. They then showed that diabetes-induced increases in sodium reabsorption cause unintuitive changes in kidney function that increase pressure on glomerular capillaries, causing protein leakage and nephron loss. The model reproduced faster disease progression observed in diabetic mice who have had one kidney removed. This mathematical understanding of diabetic kidney injury may improve translation of novel therapies from mice to human.
Collapse
|
9
|
Hou T, Su W, Guo Z, Gong MC. A Novel Diabetic Mouse Model for Real-Time Monitoring of Clock Gene Oscillation and Blood Pressure Circadian Rhythm. J Biol Rhythms 2018; 34:51-68. [PMID: 30278816 DOI: 10.1177/0748730418803719] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Diabetic patients have an increased prevalence of blood pressure (BP) circadian rhythm disruption, which is associated with an increased risk of target organ damage and detrimental cardiovascular events. Limited information is available regarding the role of clock genes in the disruption of BP circadian rhythm in diabetes due to the lack of a diabetic animal model that allows real-time monitoring of clock gene oscillation. Here, we generated a novel diabetic db/db-mPer2Luc mouse model by crossing type 2 diabetic db/db mice with mPer2Luc knock-in mice. The daily rhythms of BP, heart rate, locomotor activity, and food and water intake were acquired by radiotelemetry or using metabolic chambers. The daily oscillation of mPer2 bioluminescence was recorded by LumiCycle in real-time in tissue explants and using the IVIS system in vivo. Our results show that db/db-mPer2Luc mice are obese, diabetic, and glucose intolerant. The db/db-mPer2Luc mice displayed a compromised BP daily rhythm, which was associated with disrupted daily rhythms in baroreflex sensitivity, locomotor activity, and metabolism, but not heart rate or food and water intake. The phase of the mPer2 daily oscillation was advanced to different extents in the explanted peripheral tissues from db/db-mPer2Luc mice relative to control mice. In contrast, no phase shift was detected in mPer2 daily oscillations in the explanted SCN. Moreover, advanced phase shift of the mPer2 daily oscillation was detected in the liver, kidney and submandibular gland in vivo of db/db-mPer2Luc mice. In conclusion, the diabetic db/db-mPer2Luc mouse is a novel animal model that allows real-time monitoring of mPer2 circadian rhythms ex vivo and in vivo. The results from db/db-mPer2Luc mice suggest that the desynchrony of mPer2 daily oscillation in peripheral tissues contributes to the loss of BP daily oscillation in diabetes.
Collapse
Affiliation(s)
- Tianfei Hou
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Wen Su
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Zhenheng Guo
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky.,Research and Development, Lexington Veterans Affairs Medical Center, Lexington, Kentucky
| | - Ming C Gong
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| |
Collapse
|
10
|
Matsunaga T, Matsunaga N, Kusunose N, Ikeda E, Okazaki H, Kakimoto K, Hamamura K, Koyanagi S, Ohdo S. Angiotensin-II regulates dosing time-dependent intratumoral accumulation of macromolecular drug formulations via 24-h blood pressure rhythm in tumor-bearing mice. Biochem Biophys Res Commun 2018; 498:86-91. [PMID: 29470987 DOI: 10.1016/j.bbrc.2017.11.162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 11/24/2017] [Indexed: 01/30/2023]
Abstract
One approach to increasing pharmacotherapy effects is administering drugs at times of day when they are most effective and/or best tolerated. Circadian variation in expression of pharmacokinetics- and pharmacodynamics-related genes was shown to contribute to dosing time-dependent differences in therapeutic effects of small molecule drugs. However, influence of dosing time of day on effects of high molecular weight formulations, such as drugs encapsulated in liposomes, has not been studied in detail. This study demonstrates that blood pressure rhythm affects dosing time-dependent variation in effects of high molecular weight formulations. Systolic blood pressure in sarcoma 180-bearing mice showed significant 24-h oscillation. Intratumoral accumulation of fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA), an indicator of tumor vascular permeability, varied with dosing time of day, matching phases of blood pressure circadian rhythm. Furthermore, intratumoral accumulation of liposome-encapsulated oxaliplatin (Lipo-L-OHP) increased with increases in systolic blood pressure. Our findings suggest that circadian blood pressure oscillations may be an important factor to consider in dosing strategies for macromolecular drugs and liposomes in cancer therapy.
Collapse
Affiliation(s)
- Takashi Matsunaga
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8512, Japan
| | - Naoya Matsunaga
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8512, Japan; Department of Glocal Healthcare Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Naoki Kusunose
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8512, Japan
| | - Eriko Ikeda
- Department of Molecular Biology, Daiichi University of Pharmacy, Minami-ku, Fukuoka, 815-8511, Japan
| | - Hiroyuki Okazaki
- Department of Molecular Biology, Daiichi University of Pharmacy, Minami-ku, Fukuoka, 815-8511, Japan
| | - Keisuke Kakimoto
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8512, Japan
| | - Kengo Hamamura
- First Department of Pharmacology, Daiichi University of Pharmacy, Minami-ku, Fukuoka, 815-8511, Japan
| | - Satoru Koyanagi
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8512, Japan; Department of Glocal Healthcare Science, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Shigehiro Ohdo
- Department of Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka, 812-8512, Japan
| |
Collapse
|
11
|
Park S, Bivona BJ, Harrison-Bernard LM. Lack of contribution of nitric oxide synthase to cholinergic vasodilation in murine renal afferent arterioles. Am J Physiol Renal Physiol 2018; 314:F1197-F1204. [PMID: 29412691 DOI: 10.1152/ajprenal.00433.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously reported significant increases in neuronal nitric oxide synthase (NOS) immunostaining in renal arterioles of angiotensin type 1A receptor (AT1A) knockout mice, and in arterioles and macula densa cells of AT1A/AT1B knockout mice. The contribution of nitric oxide derived from endothelial and macula densa cells in the maintenance of afferent arteriolar tone and acetylcholine-induced vasodilation was functionally determined in kidneys of wild-type, AT1A, and AT1A/AT1B knockout mice. Acetylcholine-induced changes in arteriolar diameters of in vitro blood-perfused juxtamedullary nephrons were measured during control conditions, in the presence of the nonspecific NOS inhibitor, Nω-nitro-l-arginine methyl ester (NLA), or the highly selective neuronal NOS inhibitor, N5-(1-imino-3-butenyl)-l-ornithine (VNIO). Acetylcholine (0.1 mM) produced a significant vasoconstriction in afferent arterioles of AT1A/AT1B mice (-10.9 ± 5.1%) and no changes in afferent arteriolar diameters of AT1A knockout mice. NLA (0.01-1 mM) or VNIO (0.01-1 μM) induced significant dose-dependent vasoconstrictions (-19.8 ± 4.0% 1 mM NLA; -7.8 ± 3.5% 1 μM VNIO) in afferent arterioles of kidneys of wild-type mice. VNIO had no effect on afferent arteriole diameters of AT1A knockout or AT1A/AT1B knockout mice, suggesting nonfunctional neuronal nitric oxide synthase. These data indicate that acetylcholine produces a significant renal afferent arteriole vasodilation independently of nitric oxide synthases in wild-type mice. AT1A receptors are essential for the manifestation of renal afferent arteriole responses to neuronal nitric oxide synthase-mediated nitric oxide release.
Collapse
Affiliation(s)
- Sungmi Park
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Benjamin J Bivona
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Lisa M Harrison-Bernard
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| |
Collapse
|
12
|
Faita F, Di Lascio N, Rossi C, Kusmic C, Solini A. Ultrasonographic Characterization of the db/db Mouse: An Animal Model of Metabolic Abnormalities. J Diabetes Res 2018; 2018:4561309. [PMID: 29707583 PMCID: PMC5863337 DOI: 10.1155/2018/4561309] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/13/2017] [Accepted: 01/04/2018] [Indexed: 12/18/2022] Open
Abstract
The availability of an animal model able to reliably mirror organ damage occurring in metabolic diseases is an urgent need. These models, mostly rodents, have not been fully characterized in terms of cardiovascular, renal, and hepatic ultrasound parameters, and only sparse values can be found in literature. Aim of this paper is to provide a detailed, noninvasive description of the heart, vessels, liver, and kidneys of the db/db mouse by ultrasound imaging. Sixteen wild type and thirty-four db/db male mice (11-week-old) were studied. State-of-the-art ultrasound technology was used to acquire images of cardiovascular, renal, and hepatic districts. A set of parameters describing function of the selected organs was evaluated. db/db mice are characterized by systolic and diastolic dysfunction, confirmed by strain analysis. Abdominal aortic and carotid stiffness do not seem to be increased in diabetic rodents; furthermore, they are characterized by a smaller mean diameter for both vessels. Renal microcirculation is significantly compromised, while liver steatosis is only slightly higher in db/db mice than in controls. We offer here for the first time an in vivo detailed ultrasonographic characterization of the db/db mouse, providing a useful tool for a thoughtful choice of the right rodent model for any experimental design.
Collapse
MESH Headings
- Animals
- Aorta, Abdominal/diagnostic imaging
- Aorta, Abdominal/physiopathology
- Blood Glucose/metabolism
- Carotid Artery, Common/diagnostic imaging
- Carotid Artery, Common/physiopathology
- Diabetes Mellitus/blood
- Diabetes Mellitus/diagnostic imaging
- Diabetes Mellitus/genetics
- Diabetes Mellitus/physiopathology
- Disease Models, Animal
- Echocardiography, Doppler, Pulsed
- Genetic Predisposition to Disease
- Heart/diagnostic imaging
- Heart/physiopathology
- Lipids/blood
- Liver/diagnostic imaging
- Liver/physiopathology
- Male
- Mice, Inbred C57BL
- Microcirculation
- Perfusion Imaging/methods
- Phenotype
- Predictive Value of Tests
- Renal Artery/diagnostic imaging
- Renal Artery/physiopathology
- Renal Circulation
- Ultrasonography, Doppler, Pulsed
- Vascular Stiffness
- Ventricular Function, Left
Collapse
Affiliation(s)
- Francesco Faita
- Institute of Clinical Physiology, Italian National Research Council, Pisa, Italy
| | - Nicole Di Lascio
- Institute of Clinical Physiology, Italian National Research Council, Pisa, Italy
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Chiara Rossi
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Claudia Kusmic
- Institute of Clinical Physiology, Italian National Research Council, Pisa, Italy
| | - Anna Solini
- Department of Surgical, Medical, Molecular, and Critical Area Pathology, University of Pisa, Pisa, Italy
| |
Collapse
|
13
|
Granado M, Amor S, Fernández N, Carreño-Tarragona G, Iglesias-Cruz MC, Martín-Carro B, Monge L, García-Villalón AL. Effects of early overnutrition on the renal response to Ang II and expression of RAAS components in rat renal tissue. Nutr Metab Cardiovasc Dis 2017; 27:930-937. [PMID: 28958692 DOI: 10.1016/j.numecd.2017.06.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 06/16/2017] [Accepted: 06/29/2017] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND AIMS The aim of this study was to analyze the effects of early overnutrition (EON) on the expression of the renin angiotensin aldosterone system (RAAS) components in renal cortex, renal arteries and renal perivascular adipose tissue (PVAT), as well as the vascular response of renal arteries to Angiotensin II (Ang II). METHODS AND RESULTS On birth day litters were adjusted to twelve (L12-control) or three (L3-overfed) pups per mother. Half of the animals were sacrificed at weaning (21 days old) and the other half at 5 months of age. Ang II-induced vasoconstriction of renal artery segments increased in young overfed rats and decreased in adult overfed rats. EON decreased the gene expression of angiotensinogen (Agt), Ang II receptors AT1 and AT2 and eNOS in renal arteries of young rats, while it increased the mRNA levels of AT-2 and ET-1 in adult rats. In renal PVAT EON up-regulated the gene expression of COX-2 and TNF-α in young rats and the mRNA levels of renin receptor both in young and in adult rats. On the contrary, Ang II receptors mRNA levels were downregulated at both ages. Renal cortex of overfed rats showed increased gene expression of Agt in adult rats and of AT1 in young rats. However the mRNA levels of AT1 were decreased in the renal cortex of overfed adult rats. CONCLUSION EON is associated with alterations in the vascular response of renal arteries to Ang II and changes in the gene expression of RAAS components in renal tissue.
Collapse
MESH Headings
- Adipose Tissue/drug effects
- Adipose Tissue/metabolism
- Adipose Tissue/physiopathology
- Age Factors
- Angiotensin II/pharmacology
- Animal Nutritional Physiological Phenomena
- Animals
- Cyclooxygenase 2/genetics
- Cyclooxygenase 2/metabolism
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Gene Expression Regulation
- Kidney/blood supply
- Nitric Oxide Synthase Type III/genetics
- Nitric Oxide Synthase Type III/metabolism
- Nutritional Status
- Overnutrition/genetics
- Overnutrition/metabolism
- Overnutrition/physiopathology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Renal Artery/drug effects
- Renal Artery/metabolism
- Renal Artery/physiopathology
- Renin-Angiotensin System/drug effects
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/metabolism
- Vasoconstriction/drug effects
- Vasoconstrictor Agents/pharmacology
Collapse
Affiliation(s)
- M Granado
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; CIBER Fisiopatologia de la Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain.
| | - S Amor
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - N Fernández
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - G Carreño-Tarragona
- Servicio de Hematología, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - M C Iglesias-Cruz
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - B Martín-Carro
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - L Monge
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - A L García-Villalón
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| |
Collapse
|
14
|
Differential impact of type-1 and type-2 diabetes on control of heart rate in mice. Auton Neurosci 2015; 194:17-25. [PMID: 26725752 DOI: 10.1016/j.autneu.2015.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 11/23/2015] [Accepted: 12/14/2015] [Indexed: 01/14/2023]
Abstract
AIMS Cardiac autonomic dysfunction is a serious complication of diabetes. One consequence is disruption of the normal beat-to-beat regulation of heart rate (HR), i.e. HR variability (HRV). However, our understanding of the disease process has been limited by inconsistent HR/HRV data from previous animal studies. We hypothesized that differences in the method of measurement, time of day, and level of stress account for the differing results across studies. Thus, our aim was to systematically assess HR and HRV in two common diabetic mouse models. METHODS ECG radiotelemetry devices were implanted into db/db (type-2 diabetic), STZ-treated db/+ (type-1 diabetic), and control db/+ mice (n=4 per group). HR and HRV were analyzed over 24 h and during treadmill testing. RESULTS 24 h analysis revealed that db/db mice had an altered pattern of circadian HR changes, and STZ-treated mice had reduced HR throughout. HRV measures linked to sympathetic control were reduced in db/db mice in the early morning and early afternoon, and partially reduced in STZ-treated mice. HR response to treadmill testing was blunted in both models. CONCLUSIONS It is important to consider both time of day and level of stress when assessing HR and HRV in diabetic mice. db/db mice may have altered circadian rhythm of sympathetic control of HR, whereas STZ-treated mice have a relative reduction. This study provides baseline data and a framework for HR analysis that may guide future investigations.
Collapse
|
15
|
Mitrou N, Morrison S, Mousavi P, Braam B, Cupples WA. Transient impairment of dynamic renal autoregulation in early diabetes mellitus in rats. Am J Physiol Regul Integr Comp Physiol 2015; 309:R892-901. [DOI: 10.1152/ajpregu.00247.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 07/31/2015] [Indexed: 01/01/2023]
Abstract
Renal autoregulation is impaired in early (1 wk) diabetes mellitus (DM) induced by streptozotocin, but effective in established DM (4 wk). Furthermore nitric oxide synthesis (NOS) inhibition with NG-nitro-l-arginine methyl ester (l-NAME) significantly improved autoregulation in early DM but not in established DM. We hypothesized that autoregulation is transiently impaired in early DM because of increased NO availability in the kidney. Because of the conflicting evidence available for a role of NO in DM, we tested the hypothesis that DM reduces autoregulation effectiveness by reducing the spatial similarity of autoregulation. Male Long-Evans rats were divided into control (CON) and diabetic (DM; streptozotocin) groups and followed for either 1 wk (CON1, n = 6; DM1, n = 5) or 4 wk (CON4, n = 7; DM4, n = 7). At the end of the experiment, dynamic autoregulation was assessed in isoflurane-anesthetized rats by whole kidney RBF during baseline, NOS1 inhibition, and nonselective NOS inhibition. Kidney surface perfusion, monitored with laser speckle contrast imaging, was used to assess spatial heterogeneity of autoregulation. Autoregulation was significantly impaired in DM1 rats and not impaired in DM4 rats. l-NAME caused strong renal vasoconstriction in all rats, but did not significantly affect autoregulation dynamics. Autoregulation was more spatially heterogeneous in DM1, but not DM4. Therefore, our results, which are consistent with transient impairment of autoregulation in DM, argue against the hypothesis that this impairment is NO-dependent, and suggest that spatial properties of autoregulation may also contribute to reduced autoregulatory effectiveness in DM1.
Collapse
Affiliation(s)
- Nicholas Mitrou
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sidney Morrison
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Paymon Mousavi
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Branko Braam
- Division of Nephrology and Immunology, University of Alberta, Edmonton, Alberta, Canada; and
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - William A. Cupples
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
| |
Collapse
|
16
|
Abstract
Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.
Collapse
Affiliation(s)
- Mattias Carlström
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher S Wilcox
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William J Arendshorst
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| |
Collapse
|
17
|
Hartono SP, Knudsen BE, Lerman LO, Textor SC, Grande JP. Combined effect of hyperfiltration and renin angiotensin system activation on development of chronic kidney disease in diabetic db/db mice. BMC Nephrol 2014; 15:58. [PMID: 24708836 PMCID: PMC3984262 DOI: 10.1186/1471-2369-15-58] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 03/31/2014] [Indexed: 12/17/2022] Open
Abstract
Background Hypertension is a major risk factor for renal disease progression. However, the mechanisms by which hypertension aggravates the effects of diabetes on the kidney are incompletely understood. We tested the hypothesis that renovascular hypertension accelerates angiotensin-II-dependent kidney damage and inflammation in the db/db mouse, a model of type II diabetes. Methods Renovascular hypertension was established in db/db and wild-type control mice through unilateral renal artery stenosis (RAS); the non-stenotic contralateral kidneys evaluated 2, 4 and 6 weeks later. Angiotensin-II infusion (1000 ng/kg/min), unilateral nephrectomy, or both were also performed in db/db mice to discern the contributions of hypertension versus hyperfiltration to development of chronic renal injury in db/db mice with RAS. The effect of blood pressure reduction in db/db mice with RAS was assessed using angiotensin-receptor-blocker (ARB) or hydralazine treatment. Results Db/db mice with renovascular hypertension developed greater and more prolonged elevation of renin activity than all other groups studied. Stenotic kidneys of db/db mice developed progressive interstitial fibrosis, tubular atrophy, and interstitial inflammation. Contralateral kidneys of wild type mice with RAS showed minimal histopathologic abnormalities, whereas db/db mice with RAS developed severe diffuse mesangial sclerosis, interstitial fibrosis, tubular atrophy, and interstitial inflammation. Db/db mice with Angiotensin II-induced hypertension developed interstitial lesions and albuminuria but not mesangial matrix expansion, while nephrectomized db/db mice exhibited modest mesangial expansion and interstitial fibrosis, but not significant albuminuria. The combination of unilateral nephrectomy and angiotensin II infusion reproduced all the features of the injury albeit in a less severe manner. ARB and hydralazine were equally effective in attenuating the development of mesangial expansion in the contralateral kidneys of db/db mice with RAS. However, only ARB prevented elevation of urinary albumin/creatinine in db/db mice with RAS. Conclusion Renovascular hypertension superimposed on diabetes exacerbates development of chronic renal disease in db/db mice at least in part through interaction with the renin-angiotensin system. Both ARB and hydralazine were equally effective in reducing systolic blood pressure and in preventing renal injury in the contralateral kidney of db/db mice with renal artery stenosis. ARB but not hydralazine prevented elevation of urinary albumin/creatinine in the db/db RAS model.
Collapse
Affiliation(s)
| | | | | | | | - Joseph P Grande
- Department of Laboratory Medicine & Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
| |
Collapse
|
18
|
Harrison-Bernard LM, de Garavilla L, Bivona BJ. Enhanced vascular chymase-dependent conversion of endothelin in the diabetic kidney. Ochsner J 2013; 13:49-55. [PMID: 23532714 PMCID: PMC3603188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND Diabetic nephropathy (DN) is associated with enhanced renal, plasma, and urinary endothelin (ET)-1 levels. Chymase cleaves Big ET-1 (1-38) to ET-1 (1-31), which is further cleaved by neutral endopeptidase to ET-1 (1-21). The current study tested the hypothesis that afferent arterioles (AA) of diabetic kidneys exhibit enhanced vasoconstrictor responses to chymase-dependent intrarenal ET formation compared to control kidneys. METHODS In situ juxtamedullary AA vasoconstrictor responses to the intrarenal conversion of Big ET-1 (1-38) to ET-1 (1-21) were performed in the absence and presence of chymase inhibition in type 2 diabetic db/db and control db/m mice studied under in vitro experimental conditions. RESULTS AA vasoconstrictor responses to Big ET-1 (1-38) were significantly enhanced in diabetic compared to control kidneys. In the presence of chymase inhibition (JNJ-18054478), AA vasoconstrictor responses of diabetic kidneys to Big ET-1 (1-38) were significantly less than the responses of control kidneys. AA diameters decreased similarly to ET-1 (1-21) in diabetic and control kidneys. CONCLUSIONS AA responses to the intrarenal conversion of Big ET-1 (1-38) to ET-1 in the absence of chymase enzymatic activity were significantly reduced in kidneys of diabetic compared to control mice, while the magnitude of the vasoconstriction to ET-1 (1-21) was not different. These data suggest that AA vasoconstriction produced by the chymase-dependent pathway is significantly greater in diabetic compared to control kidneys. We propose that intrarenal chymase-dependent ET-1 production contributes to the decline in function and progression to end-stage renal disease in patients with type 2 diabetes.
Collapse
Affiliation(s)
| | | | - Benjamin J. Bivona
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA
| |
Collapse
|
19
|
Park S, Bivona BJ, Ford SM, Xu S, Kobori H, de Garavilla L, Harrison-Bernard LM. Direct evidence for intrarenal chymase-dependent angiotensin II formation on the diabetic renal microvasculature. Hypertension 2012; 61:465-71. [PMID: 23213190 DOI: 10.1161/hypertensionaha.111.202424] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Our previous work supports a major role for angiotensin-converting enzyme (ACE)-independent intrarenal angiotensin (ANG) II formation on microvascular function in type 2 diabetes mellitus. We tested the hypothesis that there is a switch from renal vascular ACE-dependent to chymase-dependent ANGII formation in diabetes mellitus. The in vitro juxtamedullary afferent arteriole (AA) contractile responses to the intrarenal conversion of the ACE-specific, chymase-resistant ANGI peptide ([Pro(10)]ANGI) to ANGII were significantly reduced in kidneys of diabetic (db/db) compared with control (db/m) mice. AA responses to the intrarenal conversion of the chymase-specific, ACE-resistant ANGI peptide ([Pro(11), D-Ala(12)]ANGI) to ANGII were significantly enhanced in kidneys of diabetic compared with control mice. AA diameters were significantly reduced by 9 ± 2, 15 ± 3, and 24 ± 3% of baseline in diabetic kidneys in response to 10, 100, and 1000 nmol/L [Pro(11), D-Ala(12)]ANGI, respectively, and the responses were significantly attenuated by angiotensin type 1 receptor or chymase-specific (JNJ-18054478) inhibition. [Pro(11), D-Ala(12)]ANGI did not produce a significant AA vasoconstriction in control kidneys. Chymase inhibition significantly attenuated ANGI-induced AA vasoconstriction in diabetic, but not control kidneys. Renal vascular mouse mast cell protease-4 or chymase/β-actin mRNA expression was significantly augmented by 5.1 ± 1.4 fold; while ACE/β-actin mRNA expression was significantly attenuated by 0.42 ± 0.08 fold in diabetic compared with control tissues. In summary, intrarenal formation of ANGII occurs primarily via ACE in the control, but via chymase in the diabetic vasculature. In conclusion, chymase-dependent mechanisms may contribute to the progression of diabetic kidney disease.
Collapse
Affiliation(s)
- Sungmi Park
- Department of Physiology, Box P7-3, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Su W, Xie Z, Guo Z, Duncan MJ, Lutshumba J, Gong MC. Altered clock gene expression and vascular smooth muscle diurnal contractile variations in type 2 diabetic db/db mice. Am J Physiol Heart Circ Physiol 2011; 302:H621-33. [PMID: 22140039 DOI: 10.1152/ajpheart.00825.2011] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study was designed to determine whether the 24-h rhythms of clock gene expression and vascular smooth muscle (VSM) contractile responses are altered in type 2 diabetic db/db mice. Control and db/db mice were euthanized at 6-h intervals throughout the day. The aorta, mesenteric arteries, heart, kidney, and brain were isolated. Clock and target gene mRNA levels were determined by either real-time PCR or in situ hybridization. Isometric contractions were measured in isolated aortic helical strips, and pressor responses to an intravenous injection of vasoconstrictors were determined in vivo using radiotelemetry. We found that the 24-h mRNA rhythms of the following genes were suppressed in db/db mice compared with control mice: the clock genes period homolog 1/2 (Per1/2) and cryptochrome 1/2 (Cry1/2) and their target genes D site albumin promoter-binding protein (Dbp) and peroxisome proliferator-activated receptor-γ (Pparg) in the aorta and mesenteric arteries; Dbp in the heart; Per1, nuclear receptor subfamily 1, group D, member 1 (Rev-erba), and Dbp in the kidney; and Per1 in the suprachiasmatic nucleus. The 24-h contractile variations in response to phenylephrine (α(1)-agonist), ANG II, and high K(+) were significantly altered in the aortas from db/db mice compared with control mice. The diurnal variations of the in vivo pressor responses to phenylephrine and ANG II were lost in db/db mice. Moreover, the 24-h mRNA rhythms of the contraction-related proteins Rho kinase 1/2, PKC-potentiated phosphatase inhibitory protein of 17 kDa, calponin-3, tropomyosin-1/2, and smooth muscle protein 22-α were suppressed in db/db mice compared with control mice. Together, our data demonstrated that the 24-h rhythms of clock gene mRNA, mRNA levels of several contraction-related proteins, and VSM contraction were disrupted in db/db mice, which may contribute to the disruption of their blood pressure circadian rhythm.
Collapse
Affiliation(s)
- Wen Su
- Departments of Physiology, University of Kentucky Medical Center, Lexington, KY 40536, USA
| | | | | | | | | | | |
Collapse
|
21
|
Bivona BJ, Park S, Harrison-Bernard LM. Glomerular filtration rate determinations in conscious type II diabetic mice. Am J Physiol Renal Physiol 2010; 300:F618-25. [PMID: 21147841 DOI: 10.1152/ajprenal.00421.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Diabetic nephropathy is a major cause of end-stage renal disease worldwide. The current studies were performed to determine the later stages of the progression of renal disease in type II diabetic mice (BKS; db/db). Methodology was developed for determining glomerular filtration rate (GFR) in conscious, chronically instrumented mice using continuous intravenous infusion of FITC-labeled inulin to achieve a steady-state plasma inulin concentration. Obese diabetic mice exhibited increased GFR compared with control mice. GFR averaged 0.313 ± 0.018 and 0.278 ± 0.007 ml/min in 18-wk-old obese diabetic (n = 11) and control (n = 13) mice, respectively (P < 0.05). In 28-wk-old obese diabetic (n = 10) and control (n = 15) mice, GFR averaged 0.348 ± 0.030 and 0.279 ± 0.009 ml/min, respectively (P < 0.05). GFR expressed per gram BW was significantly reduced in 18- and 28-wk-old obese diabetic compared with control mice (5.9 ± 0.3 vs. 9.0 ± 0.3; 6.6 ± 0.6 vs. 7.8 ± 0.3 μl·min(-1)·g body wt(-1)), respectively (P < 0.05). However, older nonobese type II diabetic mice had significantly reduced GFR (0.179 ± 0.023 ml/min; n = 6) and elevated urinary albumin excretion (811 ± 127 μg/day) compared with obese diabetic and control mice (514 ± 54, 171 ± 18 μg/day), which are consistent with the advanced stages of renal disease. These studies suggest that hyperfiltration contributes to the progression of renal disease in type II diabetic mice.
Collapse
Affiliation(s)
- Benjamin J Bivona
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | | | | |
Collapse
|
22
|
Abstract
PURPOSE OF REVIEW Diabetes mellitus is the primary cause of end-stage renal disease, yet the mechanisms underlying diabetic nephropathy remain ill-defined. The widely accepted opinion holds that events occurring early during the course of diabetes engender the eventual decline in renal function. This review will summarize recent advances (published January 2008 through June 2009) regarding the renal vascular and glomerular functional changes that occur during the early stage of diabetes. RECENT FINDINGS Reduced C-peptide levels and increased cyclooxygenase-2 activity both seem to promote diabetic hyperfiltration, presumably via effects on afferent arteriolar tone. In addition, exaggerated tonic influences of K+ channels on afferent arteriolar function likely act in concert with impaired Ca2+ influx responses to changes in membrane potential to promote vasodilation. Mechanisms underlying these changes remain largely speculative. Diabetes may also alter autoregulation of renal blood flow and glomerular filtration rate, as well as provoke afferent arteriolar dilation secondary to alterations in proximal tubular reabsorption; however, conflicting evidence continues to flood the literature concerning these events. SUMMARY New evidence has expanded our appreciation of the complexity of events that promote preglomerular vasodilation during the early stage of diabetes; however, it seems that the more we know, the less we understand.
Collapse
|
23
|
Park S, Bivona BJ, Kobori H, Seth DM, Chappell MC, Lazartigues E, Harrison-Bernard LM. Major role for ACE-independent intrarenal ANG II formation in type II diabetes. Am J Physiol Renal Physiol 2009; 298:F37-48. [PMID: 19846569 DOI: 10.1152/ajprenal.00519.2009] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Combination therapy of angiotensin-converting enzyme (ACE) inhibition and AT(1) receptor blockade has been shown to provide greater renoprotection than ACE inhibitor alone in human diabetic nephropathy, suggesting that ACE-independent pathways for ANG II formation are of major significance in disease progression. Studies were performed to determine the magnitude of intrarenal ACE-independent formation of ANG II in type II diabetes. Although renal cortical ACE protein activity [2.1 +/- 0.8 vs. 9.2 +/- 2.1 arbitrary fluorescence units (AFU) x mg(-1) x min(-1)] and intensity of immunohistochemical staining were significantly reduced and ACE2 protein activity (16.7 +/- 3.2 vs. 7.2 +/- 2.4 AFU x mg(-1) x min(-1)) and intensity elevated, kidney ANG I (113 +/- 24 vs. 110 +/- 45 fmol/g) and ANG II (1,017 +/- 165 vs. 788 +/- 99 fmol/g) levels were not different between diabetic and control mice. Afferent arteriole vasoconstriction due to conversion of ANG I to ANG II was similar in magnitude in kidneys of diabetic (-28 +/- 3% at 1 microM) and control (-23 +/- 3% at 1 microM) mice; a response completely inhibited by AT(1) receptor blockade. In control kidneys, afferent arteriole vasoconstriction produced by ANG I was significantly attenuated by ACE inhibition, but not by serine protease inhibition. In contrast, afferent arteriole vasoconstriction produced by intrarenal conversion of ANG I to ANG II was significantly attenuated by serine protease inhibition, but not by ACE inhibition in diabetic kidneys. In conclusion, there is a switch from ACE-dependent to serine protease-dependent ANG II formation in the type II diabetic kidney. Pharmacological targeting of these serine protease-dependent pathways may provide further protection from diabetic renal vascular disease.
Collapse
|
24
|
Senador D, Kanakamedala K, Irigoyen MC, Morris M, Elased KM. Cardiovascular and autonomic phenotype of db/db diabetic mice. Exp Physiol 2009; 94:648-58. [PMID: 19218356 DOI: 10.1113/expphysiol.2008.046474] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The db/db mice serve as a good model for type 2 diabetes characterized by hyperinsulinaemia and progressive hyperglycaemia. There are limited and conflicting data on the cardiovascular changes in this model. The aim of the present study was to characterize the cardiovascular and autonomic phenotype of male db/db mice and evaluate the role of angiotensin II AT(1) receptors. Radiotelemetry was used to monitor 24 h blood pressure (BP) in mice for 8 weeks. Parameters measured were mean arterial pressure (MAP), heart rate (HR) and their variabilities. In 8-week-old db/db mice, the MAP and BP circadian rhythms were not different from age-matched control mice, while HR and locomotor activity were decreased. With ageing, MAP gradually increased in db/db mice, and the 12 h light values did not dip significantly from the 12 h dark periods. In 14-week-old mice, MAP was increased during light (101 +/- 1 versus 117 +/- 2 mmHg, P < 0.01; control versus db/db mice) and dark phases (110 +/- 1.7 versus 121 +/- 3.1 mmHg, P < 0.01; control versus db/db mice). This increase in MAP was associated with a significant increase in plasma angiotensin-converting enzyme activity and angiotensin II levels. Chronic treatment with losartan (10 mg kg(-1) day(-1)) blocked the increase in MAP in db/db mice, with no effect in control animals. Spectral analysis was used to monitor autonomic cardiovascular function. The circadian rhythm observed in systolic arterial pressure variance and its low-frequency component in control mice was absent in db/db mice. There were no changes in HR variability and spontaneous baroreflex sensitivity between control and db/db mice. The results document an age-related increase in MAP in db/db mice, which can be reduced by antagonism of angiotensin II AT(1) receptors, and alterations in autonomic balance and components of the renin-angiotensin system.
Collapse
Affiliation(s)
- Danielle Senador
- Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | | | | | | | | |
Collapse
|