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Bao Y, Frisbee AC, Frisbee JC, Goldman D. A constrained constructive optimization model of branching arteriolar networks in rat skeletal muscle. J Appl Physiol (1985) 2024; 136:1303-1321. [PMID: 38601995 DOI: 10.1152/japplphysiol.00896.2023] [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: 12/15/2023] [Revised: 03/11/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024] Open
Abstract
Blood flow regulation within the microvasculature reflects a complex interaction of regulatory mechanisms and varies spatially and temporally according to conditions such as metabolism, growth, injury, and disease. Understanding the role of microvascular flow distributions across conditions is of interest to investigators spanning multiple disciplines; however, data collection within networks can be labor-intensive and challenging due to limited resolution. To overcome these experimental challenges, computational network models that can accurately simulate vascular behavior are highly beneficial. Constrained constructive optimization (CCO) is a commonly used algorithm for vascular simulation, particularly well known for its adaptability toward vascular modeling across tissues. The present work demonstrates an implementation of CCO aimed to simulate a branching arteriolar microvasculature in healthy skeletal muscle, validated against literature including comprehensive rat gluteus maximus vasculature datasets, and reviews a list of user-specified adjustable model parameters to understand how their variability affects the simulated networks. Network geometric properties, including mean element diameters, lengths, and numbers of bifurcations per order, Horton's law ratios, and fractal dimension, demonstrate good validation once model parameters are adjusted to experimental data. This model successfully demonstrates hemodynamic properties such as Murray's law and the network Fahraeus effect. Application of centrifugal and Strahler ordering schemes results in divergent descriptions of identical simulated networks. This work introduces a novel CCO-based model focused on generating branching skeletal muscle microvascular arteriolar networks based on adjustable model parameters, thus making it a valuable tool for investigations into skeletal muscle microvascular structure and tissue perfusion.NEW & NOTEWORTHY The present work introduces a CCO-based algorithm for generating branching arteriolar networks, with adjustable model parameters to enable modeling in varying skeletal muscle tissues. The geometric and hemodynamic parameters of the generated networks have been comprehensively validated using experimental data collected previously in-house and from literature. This is one of few validated CCO-based models to specialize in skeletal muscle microvasculature and acts as a beneficial tool for investigating the microvasculature for hypothesis testing and validation.
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Affiliation(s)
- Yuki Bao
- Department of Biomedical Engineering, University of Western Ontario, London, Ontario, Canada
| | - Amelia C Frisbee
- Department of Physics, University of Guelph, Guelph, Ontario, Canada
| | - Jefferson C Frisbee
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
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2
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DeLorey DS, Clifford PS. Does sympathetic vasoconstriction contribute to metabolism: Perfusion matching in exercising skeletal muscle? Front Physiol 2022; 13:980524. [PMID: 36171966 PMCID: PMC9510655 DOI: 10.3389/fphys.2022.980524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/17/2022] [Indexed: 11/14/2022] Open
Abstract
The process of matching skeletal muscle blood flow to metabolism is complex and multi-factorial. In response to exercise, increases in cardiac output, perfusion pressure and local vasodilation facilitate an intensity-dependent increase in muscle blood flow. Concomitantly, sympathetic nerve activity directed to both exercising and non-active muscles increases as a function of exercise intensity. Several studies have reported the presence of tonic sympathetic vasoconstriction in the vasculature of exercising muscle at the onset of exercise that persists through prolonged exercise bouts, though it is blunted in an exercise-intensity dependent manner (functional sympatholysis). The collective evidence has resulted in the current dogma that vasoactive molecules released from skeletal muscle, the vascular endothelium, and possibly red blood cells produce local vasodilation, while sympathetic vasoconstriction restrains vasodilation to direct blood flow to the most metabolically active muscles/fibers. Vascular smooth muscle is assumed to integrate a host of vasoactive signals resulting in a precise matching of muscle blood flow to metabolism. Unfortunately, a critical review of the available literature reveals that published studies have largely focused on bulk blood flow and existing experimental approaches with limited ability to reveal the matching of perfusion with metabolism, particularly between and within muscles. This paper will review our current understanding of the regulation of sympathetic vasoconstriction in contracting skeletal muscle and highlight areas where further investigation is necessary.
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Affiliation(s)
- Darren S. DeLorey
- Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, AB, Canada
- *Correspondence: Darren S. DeLorey,
| | - Philip S. Clifford
- College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, United States
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3
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Xu Y, Ward AD, Goldman D, Yin H, Arpino JM, Nong Z, Lee JJ, O'Neil C, Pickering JG. Arteriolar dysgenesis in ischemic, regenerating skeletal muscle revealed by automated micro-morphometry, computational modeling, and perfusion analysis. Am J Physiol Heart Circ Physiol 2022; 323:H38-H48. [PMID: 35522554 DOI: 10.1152/ajpheart.00010.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rebuilding the local vasculature is central to restoring the health of muscles subjected to ischemic injury. Arteriogenesis yields remodeled collateral arteries that circumvent the obstruction, and angiogenesis produces capillaries to perfuse the regenerating myofibers. However, the vital intervening network of arterioles that feed the regenerated capillaries is poorly understood and an investigative challenge. We used machine learning and automated micro-morphometry to quantify the arteriolar landscape in distal hindlimb muscles in mice that have regenerated after femoral artery excision. Assessment of 1546 arteriolar sections revealed a striking (> 2-fold) increase in arteriolar density in regenerated muscle 14 and 28 days after ischemic injury. Lumen caliber was initially similar to that of control arterioles but after 4 weeks lumen area was reduced by 46%. In addition, the critical smooth muscle layer was attenuated throughout the arteriolar network, across a 150 to 5 µm diameter range. To understand the consequences of the reshaped distal hindlimb arterioles, we undertook computational flow modeling which revealed blunted flow augmentation. Moreover, impaired flow reserve was confirmed in vivo by laser Doppler analyses of flow in response to directly applied sodium nitroprusside. Thus, in hindlimb muscles regenerating after ischemic injury, the arteriolar network is amplified, inwardly remodels, and is diffusely under-muscularized. These defects and the associated flow restraints could contribute to the deleterious course of peripheral artery disease and merit attention when considering therapeutic innovations.
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Affiliation(s)
- Yiwen Xu
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Aaron D Ward
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Hao Yin
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - John-Michael Arpino
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Zengxuan Nong
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - Jason J Lee
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.,Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Caroline O'Neil
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada
| | - J Geoffrey Pickering
- Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.,Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.,Department of Biochemistry, University of Western Ontario, London, Ontario, Canada.,Department of Medicine, University of Western Ontario, London, Ontario, Canada
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4
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Abstract
Dipeptidyl peptidase IV (DPP-IV) is a unique serine protease that exists in a membrane bound state and in a soluble state in most tissues in the body. DPP-IV has multiple targets including cytokines, neuropeptides, and incretin hormones, and plays an important role in health and disease. Recent work suggests that skeletal muscle releases DPP-IV as a myokine and participates in control of muscle blood flow. However, few of the functions of DPP-IV as a myokine have been investigated to date and there is a poor understanding about what causes DPP-IV to be released from muscle.
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Affiliation(s)
- Heidi A Kluess
- School of Kinesiology, Auburn University, Auburn, AL, United States
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5
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Akerstrom T, Goldman D, Nilsson F, Milkovich SL, Fraser GM, Brand CL, Hellsten Y, Ellis CG. Hyperinsulinemia does not cause de novo capillary recruitment in rat skeletal muscle. Microcirculation 2019; 27:e12593. [PMID: 31605649 PMCID: PMC7064932 DOI: 10.1111/micc.12593] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 09/05/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022]
Abstract
Objective The effect of insulin on blood flow distribution within muscle microvasculature has been suggested to be important for glucose metabolism. However, the “capillary recruitment” hypothesis is still controversial and relies on studies using indirect contrast‐enhanced ultrasound (CEU) methods. Methods We studied how hyperinsulinemia effects capillary blood flow in rat extensor digitorum longus (EDL) muscle during euglycemic hyperinsulinemic clamp using intravital video microscopy (IVVM). Additionally, we modeled blood flow and microbubble distribution within the vascular tree under conditions observed during euglycemic hyperinsulinemic clamp experiments. Results Euglycemic hyperinsulinemia caused an increase in erythrocyte (80 ± 25%, P < .01) and plasma (53 ± 12%, P < .01) flow in rat EDL microvasculature. We found no evidence of de novo capillary recruitment within, or among, capillary networks supplied by different terminal arterioles; however, erythrocyte flow became slightly more homogenous. Our computational model predicts that a decrease in asymmetry at arteriolar bifurcations causes redistribution of microbubble flow among capillaries already perfused with erythrocytes and plasma, resulting in 25% more microbubbles flowing through capillaries. Conclusions Our model suggests increase in CEU signal during hyperinsulinemia reflects a redistribution of arteriolar flow and not de novo capillary recruitment. IVVM experiments support this prediction showing increases in erythrocyte and plasma flow and not capillary recruitment.
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Affiliation(s)
- Thorbjorn Akerstrom
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
| | - Franciska Nilsson
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Stephanie L Milkovich
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
| | - Graham M Fraser
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | | | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, University of Copenhagen, Copenhagen, Denmark
| | - Christopher G Ellis
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Canada
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6
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Neidert LE, Al-Tarhuni M, Goldman D, Kluess HA, Jackson DN. Endogenous dipeptidyl peptidase IV modulates skeletal muscle arteriolar diameter in rats. Physiol Rep 2019; 6. [PMID: 29380955 PMCID: PMC5789721 DOI: 10.14814/phy2.13564] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/06/2017] [Accepted: 12/09/2017] [Indexed: 01/17/2023] Open
Abstract
The purpose of this study is to investigate that dipeptidyl peptidase IV (DPP‐IV) released from skeletal and vascular smooth muscle can increase arteriolar diameter in a skeletal muscle vascular bed by reducing neuropeptide Y (NPY)‐mediated vasoconstriction. We hypothesized that the effect of myokine DPP‐IV would be greatest in the smallest and least in the largest arterioles. Eight male Sprague Dawley rats (age 7–9 weeks; mass, mean ± SD: 258 ± 41 g) were anesthetized and the gluteus maximus dissected in situ for intravital microscopy analysis of arteriolar diameter of the vascular network. Computational modeling was performed on the diameter measurements to evaluate the overall impact of diameter changes on network resistance and flow distribution. In the first set of experiments, whey protein isolate powder was added to physiological saline solution, put in a heated reservoir, and applied to the preparation to induce release of DPP‐IV from the muscle. This resulted in an order‐dependent increase in arteriolar diameter, with the largest change in the 6A arterioles (63% more reactive than 1A arterioles; P < 0.05). This effect was abolished by adding the DPP‐IV inhibitor, Diprotin A. To test if the DPP‐IV released was affecting NPY‐mediated vasoconstriction, we applied NPY and whey protein, which resulted in attenuated vasoconstriction. These findings suggest that DPP‐IV is released from muscle and has a unique effect on blood flow, which appears to act on NPY to attenuate vasoconstriction. The findings suggest that DPP‐IV released from the skeletal or smooth muscle can alter muscle blood flow.
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Affiliation(s)
| | - Mohammed Al-Tarhuni
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Heidi A Kluess
- School of Kinesiology, Auburn University, Auburn, Alabama
| | - Dwayne N Jackson
- Department of Medical Biophysics, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
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7
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Novielli-Kuntz NM, Lemaster KA, Frisbee JC, Jackson DN. Neuropeptide Y1 and alpha-1 adrenergic receptor-mediated decreases in functional vasodilation in gluteus maximus microvascular networks of prediabetic mice. Physiol Rep 2018; 6:e13755. [PMID: 29981203 PMCID: PMC6035337 DOI: 10.14814/phy2.13755] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/06/2018] [Accepted: 06/08/2018] [Indexed: 12/27/2022] Open
Abstract
Prediabetes is associated with impaired contraction‐evoked dilation of skeletal muscle arterioles, which may be due to increased sympathetic activity accompanying this early stage of diabetes disease. Herein, we sought to determine whether blunted contraction‐evoked vasodilation resulted from enhanced sympathetic neuropeptide Y1 receptor (Y1R) and alpha‐1 adrenergic receptor (α1R) activation. Using intravital video microscopy, second‐, third‐, and fourth‐order (2A, 3A, and 4A) arteriolar diameters were measured before and following electrical field stimulation of the gluteus maximus muscle (GM) in prediabetic (PD, Pound Mouse) and control (CTRL, c57bl6, CTRL) mice. Baseline diameter was similar between groups; however, single tetanic contraction (100 Hz; 400 and 800 msec) and sustained rhythmic contraction (2 and 8 Hz, 30 sec) evoked rapid onset vasodilation and steady‐state vasodilatory responses that were blunted by 50% or greater in PD versus CTRL. Following Y1R and α1R blockade with sympathetic antagonists BIBP3226 and prazosin, contraction‐evoked arteriolar dilation in PD was restored to levels observed in CTRL. Furthermore, arteriolar vasoconstrictor responses to NPY (10−13–10−8 mol/L) and PE (10−9–10−5 mol/L) were greater in PD versus CTRL at higher concentrations, especially at 3A and 4A. These findings suggest that contraction‐evoked vasodilation in PD is blunted by Y1R and α1R receptor activation throughout skeletal muscle arteriolar networks.
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Affiliation(s)
| | - Kent A Lemaster
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - Jefferson C Frisbee
- Department of Medical Biophysics, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - Dwayne N Jackson
- Department of Medical Biophysics, Western University, London, Ontario, Canada
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8
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Farid Z, Saleem AH, Al-Khazraji BK, Jackson DN, Goldman D. Estimating blood flow in skeletal muscle arteriolar trees reconstructed from in vivo data using the Fry approach. Microcirculation 2018; 24. [PMID: 28470885 DOI: 10.1111/micc.12378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/27/2017] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To develop a computational method to accurately predict blood flow in skeletal muscle arteriolar trees in the absence of complete boundary data. METHODS We used arteriolar trees in the rat GM muscle that were reconstructed from montages obtained via IVVM, and incorporated a recently published method for approximating unknown b.c.'s into our existing two-phase, steady-state blood flow model. For varying numbers of unknown b.c.'s, we used the new flow model and GM geometry to approximately match RBC flows corresponding to experimental measurements. RESULTS We showed this method gives errors that decrease as the number of unknown b.c.'s decreases. We also showed that specifying total blood flow decreases the mean RBC flow error and its variability. By varying required target values of intravascular pressure and wall shear stress, we showed results are less sensitive to target pressure. Finally, we developed and validated a method for determining target values, so that network hemodynamics and resistance can be accurately calculated based only on measured or estimated total blood flow. CONCLUSIONS We have developed and validated a computational method that can accurately estimate RBC flow distribution in skeletal muscle arteriolar trees in the absence of complete boundary data.
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Affiliation(s)
- Zahra Farid
- Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada
| | - Amani H Saleem
- Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada
| | - Baraa K Al-Khazraji
- Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada
| | - Dwayne N Jackson
- Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada.,Graduate Program in Biomedical Engineering, The University of Western Ontario, London, ON, Canada
| | - Daniel Goldman
- Department of Medical Biophysics, The University of Western Ontario, London, ON, Canada.,Graduate Program in Biomedical Engineering, The University of Western Ontario, London, ON, Canada
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9
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Mandel ER, Dunford EC, Abdifarkosh G, Turnbull PC, Perry CGR, Riddell MC, Haas TL. The superoxide dismutase mimetic tempol does not alleviate glucocorticoid-mediated rarefaction of rat skeletal muscle capillaries. Physiol Rep 2018; 5:e13243. [PMID: 28533261 PMCID: PMC5449555 DOI: 10.14814/phy2.13243] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/13/2017] [Accepted: 03/16/2017] [Indexed: 12/17/2022] Open
Abstract
Sustained elevations in circulating glucocorticoids elicit reductions in skeletal muscle microvascular content, but little is known of the underlying mechanisms. We hypothesized that glucocorticoid‐induced oxidative stress contributes to this phenomenon. In rats that were implanted with corticosterone (CORT) or control pellets, CORT caused a significant decrease in muscle glutathione levels and a corresponding increase in protein carbonylation, an irreversible oxidative modification of proteins. Decreased endothelial nitric oxide synthase and increased endothelin‐1 mRNA levels were detected after 9 days of CORT, and blood flow to glycolytic muscles was diminished. Control and CORT rats were treated concurrently with drinking water containing the superoxide dismutase mimetic tempol (172 mg/L) or the α‐1 adrenergic receptor antagonist prazosin (50 mg/L) for 6 or 16 days. Both tempol and prazosin alleviated skeletal muscle protein carbonylation. Tempol failed to prevent CORT‐mediated capillary rarefaction and was ineffective in restoring skeletal muscle blood flow. In contrast, prazosin blocked capillary rarefaction and restored skeletal muscle blood flow to control levels. The failure of tempol to prevent CORT‐induced skeletal muscle microvascular rarefaction does not support a dominant role of superoxide‐induced oxidative stress in this process. Although a decrease in protein carbonylation was observed with prazosin treatment, our data suggest that the maintenance of skeletal muscle microvascular content is related more closely with counteracting the CORT‐mediated influence on skeletal muscle vascular tone.
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Affiliation(s)
- Erin R Mandel
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Emily C Dunford
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Ghoncheh Abdifarkosh
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Patrick C Turnbull
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Christopher G R Perry
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Michael C Riddell
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
| | - Tara L Haas
- School of Kinesiology and Health Science and the Muscle Health Research Centre, York University, Toronto, Ontario, Canada
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10
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Mueller PJ, Clifford PS, Crandall CG, Smith SA, Fadel PJ. Integration of Central and Peripheral Regulation of the Circulation during Exercise: Acute and Chronic Adaptations. Compr Physiol 2017; 8:103-151. [DOI: 10.1002/cphy.c160040] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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11
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Burnstock G. Purinergic Signaling in the Cardiovascular System. Circ Res 2017; 120:207-228. [PMID: 28057794 DOI: 10.1161/circresaha.116.309726] [Citation(s) in RCA: 267] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/21/2016] [Accepted: 11/23/2016] [Indexed: 02/07/2023]
Abstract
There is nervous control of the heart by ATP as a cotransmitter in sympathetic, parasympathetic, and sensory-motor nerves, as well as in intracardiac neurons. Centers in the brain control heart activities and vagal cardiovascular reflexes involve purines. Adenine nucleotides and nucleosides act on purinoceptors on cardiomyocytes, AV and SA nodes, cardiac fibroblasts, and coronary blood vessels. Vascular tone is controlled by a dual mechanism. ATP, released from perivascular sympathetic nerves, causes vasoconstriction largely via P2X1 receptors. Endothelial cells release ATP in response to changes in blood flow (via shear stress) or hypoxia, to act on P2 receptors on endothelial cells to produce nitric oxide, endothelium-derived hyperpolarizing factor, or prostaglandins to cause vasodilation. ATP is also released from sensory-motor nerves during antidromic reflex activity, to produce relaxation of some blood vessels. Purinergic signaling is involved in the physiology of erythrocytes, platelets, and leukocytes. ATP is released from erythrocytes and platelets, and purinoceptors and ectonucleotidases are expressed by these cells. P1, P2Y1, P2Y12, and P2X1 receptors are expressed on platelets, which mediate platelet aggregation and shape change. Long-term (trophic) actions of purine and pyrimidine nucleosides and nucleotides promote migration and proliferation of vascular smooth muscle and endothelial cells via P1 and P2Y receptors during angiogenesis, vessel remodeling during restenosis after angioplasty and atherosclerosis. The involvement of purinergic signaling in cardiovascular pathophysiology and its therapeutic potential are discussed, including heart failure, infarction, arrhythmias, syncope, cardiomyopathy, angina, heart transplantation and coronary bypass grafts, coronary artery disease, diabetic cardiomyopathy, hypertension, ischemia, thrombosis, diabetes mellitus, and migraine.
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Affiliation(s)
- Geoffrey Burnstock
- From the Autonomic Neuroscience Institute, Royal Free and University College Medical School, London, United Kingdom.
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12
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Arpino JM, Nong Z, Li F, Yin H, Ghonaim N, Milkovich S, Balint B, O’Neil C, Fraser GM, Goldman D, Ellis CG, Pickering JG. Four-Dimensional Microvascular Analysis Reveals That Regenerative Angiogenesis in Ischemic Muscle Produces a Flawed Microcirculation. Circ Res 2017; 120:1453-1465. [DOI: 10.1161/circresaha.116.310535] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 01/20/2017] [Accepted: 02/07/2017] [Indexed: 12/19/2022]
Abstract
Rationale:
Angiogenesis occurs after ischemic injury to skeletal muscle, and enhancing this response has been a therapeutic goal. However, to appropriately deliver oxygen, a precisely organized and exquisitely responsive microcirculation must form. Whether these network attributes exist in a regenerated microcirculation is unknown, and methodologies for answering this have been lacking.
Objective:
To develop 4-dimensional methodologies for elucidating microarchitecture and function of the reconstructed microcirculation in skeletal muscle.
Methods and Results:
We established a model of complete microcirculatory regeneration after ischemia-induced obliteration in the mouse extensor digitorum longus muscle. Dynamic imaging of red blood cells revealed the regeneration of an extensive network of flowing neo-microvessels, which after 14 days structurally resembled that of uninjured muscle. However, the skeletal muscle remained hypoxic. Red blood cell transit analysis revealed slow and stalled flow in the regenerated capillaries and extensive arteriolar-venular shunting. Furthermore, spatial heterogeneity in capillary red cell transit was highly constrained, and red blood cell oxygen saturation was low and inappropriately variable. These abnormalities persisted to 120 days after injury. To determine whether the regenerated microcirculation could regulate flow, the muscle was subjected to local hypoxia using an oxygen-permeable membrane. Hypoxia promptly increased red cell velocity and flux in control capillaries, but in neocapillaries, the response was blunted. Three-dimensional confocal imaging revealed that neoarterioles were aberrantly covered by smooth muscle cells, with increased interprocess spacing and haphazard actin microfilament bundles.
Conclusions:
Despite robust neovascularization, the microcirculation formed by regenerative angiogenesis in skeletal muscle is profoundly flawed in both structure and function, with no evidence for normalizing over time. This network-level dysfunction must be recognized and overcome to advance regenerative approaches for ischemic disease.
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Affiliation(s)
- John-Michael Arpino
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Zengxuan Nong
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Fuyan Li
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Hao Yin
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Nour Ghonaim
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Stephanie Milkovich
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Brittany Balint
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Caroline O’Neil
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Graham M. Fraser
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Daniel Goldman
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - Christopher G. Ellis
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
| | - J. Geoffrey Pickering
- From the Robarts Research Institute (J.-M.A., Z.N., F.L., H.Y., B.B., C.O., J.G.P.), Departments of Medicine (C.G.E., J.G.P.), Medical Biophysics (J.-M.A., S.M., B.B., G.M.F., D.G., C.G.E., J.G.P.), Biochemistry (J.G.P.), and Biomedical Engineering (N.G., D.G.), Western University, London, Canada; and Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, Canada (G.M.F.)
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13
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Lemaster K, Jackson D, Welsh DG, Brooks SD, Chantler PD, Frisbee JC. Altered distribution of adrenergic constrictor responses contributes to skeletal muscle perfusion abnormalities in metabolic syndrome. Microcirculation 2016; 24. [PMID: 28036148 DOI: 10.1111/micc.12349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 12/28/2016] [Indexed: 12/30/2022]
Abstract
PURPOSE Although studies suggest elevated adrenergic activity paralleling metabolic syndrome in OZRs, the moderate hypertension and modest impact on organ perfusion question the multi-scale validity of these data. METHODS To understand how adrenergic function contributes to vascular reactivity in OZR, we utilized a multi-scale approach to investigate pressure responses, skeletal muscle blood flow, and vascular reactivity following adrenergic challenge. RESULTS For OZR, adrenergic challenge resulted in increased pressor responses vs LZRs, mediated via α1 receptors, with minimal contribution by either ROS or NO bioavailability. In situ gastrocnemius muscle of OZR exhibited blunted functional hyperemia, partially restored with α1 inhibition, although improved muscle performance and VO2 required combined treatment with TEMPOL. Within OZR in situ cremaster muscle, proximal arterioles exhibited a more heterogeneous constriction to adrenergic challenge, biased toward hyperresponsiveness, vs LZR. This increasingly heterogeneous pattern was mirrored in ex vivo arterioles, mediated via α1 receptors, with roles for ROS and NO bioavailability evident in hyperresponsive vessels only. CONCLUSIONS These results support the central role of the α1 adrenoreceptor for augmented pressor responses and elevations in vascular resistance, but identify an increased heterogeneity of constrictor reactivity in OZR that is presently of unclear purpose.
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Affiliation(s)
- Kent Lemaster
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Dwayne Jackson
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Donald G Welsh
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Steven D Brooks
- Division of Exercise Physiology, West Virginia University Health Sciences Center, Morgantown, WV, USA
| | - Paul D Chantler
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Jefferson C Frisbee
- Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, WV, USA
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14
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Just TP, DeLorey DS. Exercise training and α1-adrenoreceptor-mediated sympathetic vasoconstriction in resting and contracting skeletal muscle. Physiol Rep 2016; 4:4/3/e12707. [PMID: 26869686 PMCID: PMC4758927 DOI: 10.14814/phy2.12707] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Exercise training (ET) increases sympathetic vasoconstrictor responsiveness and enhances contraction‐mediated inhibition of sympathetic vasoconstriction (i.e., sympatholysis) through a nitric oxide (NO)‐dependent mechanism. Changes in α2‐adrenoreceptor vasoconstriction mediate a portion of these training adaptations, however the contribution of other postsynaptic receptors remains to be determined. Therefore, the purpose of this study was to investigate the effect of ET on α1‐adrenoreceptor‐mediated vasoconstriction in resting and contracting muscle. It was hypothesized that α1‐adrenoreceptor‐mediated sympatholysis would be enhanced following ET. Male Sprague Dawley rats were randomized to sedentary (S; n = 12) or heavy‐intensity treadmill ET (n = 11) groups. Subsequently, rats were anesthetized and instrumented for lumbar sympathetic chain stimulation and measurement of femoral vascular conductance (FVC) at rest and during muscle contraction. The percentage change in FVC in response to sympathetic stimulation was measured in control, α1‐adrenoreceptor blockade (Prazosin; 20 μg, IV), and combined α1 and NO synthase (NOS) blockade (l‐NAME; 5 mg·kg−1IV) conditions. Sympathetic vasoconstrictor responsiveness was increased (P < 0.05) in ET compared to S rats at low, but not high (P > 0.05) stimulation frequencies at rest (S: 2 Hz: −25 ± 4%; 5 Hz: −45 ± 5 %; ET: 2 Hz: −35 ± 7%, 5 Hz: −52 ± 7%), whereas sympathetic vasoconstrictor responsiveness was not different (P > 0.05) between groups during contraction (S: 2 Hz: −11 ± 8%; 5 Hz: −26 ± 11%; ET: 2 Hz: −10 ± 7%, 5 Hz: −27 ± 12%). Prazosin blunted (P < 0.05) vasoconstrictor responsiveness in S and ET rats at rest and during contraction, and abolished group differences in vasoconstrictor responsiveness. Subsequent NOS blockade increased vasoconstrictor responses (P < 0.05) in S at rest and during contraction, whereas in ET vasoconstriction was increased (P < 0.05) in response to sympathetic stimulation at 2 Hz at rest and unchanged (P > 0.05) during contraction. ET enhanced (P < 0.05) sympatholysis, however the training‐mediated improvements in sympatholysis were abolished by α1‐adrenoreceptor blockade. Subsequent NOS inhibition did not alter (P > 0.05) sympatholysis in S or ET rats. In conclusion, ET augmented α1‐adrenoreceptor‐mediated vasoconstriction in resting skeletal muscle and enhanced α1‐adrenoreceptor‐mediated sympatholysis. Furthermore, these data suggest that NO is not required to inhibit α2‐adrenoreceptor‐ and nonadrenoreceptor‐mediated vasoconstriction during exercise.
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Affiliation(s)
- Timothy P Just
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Darren S DeLorey
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB, Canada
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15
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Al Tarhuni M, Goldman D, Jackson DN. ComprehensiveIn SituAnalysis of Arteriolar Network Geometry and Topology in Rat Gluteus Maximus Muscle. Microcirculation 2016; 23:456-67. [DOI: 10.1111/micc.12292] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/24/2016] [Indexed: 01/10/2023]
Affiliation(s)
- Mohammed Al Tarhuni
- Department of Medical Biophysics; The University of Western Ontario; London Ontario Canada
| | - Daniel Goldman
- Department of Medical Biophysics; The University of Western Ontario; London Ontario Canada
- Biomedical Engineering Graduate Program; The University of Western Ontario; London Ontario Canada
| | - Dwayne N. Jackson
- Department of Medical Biophysics; The University of Western Ontario; London Ontario Canada
- Biomedical Engineering Graduate Program; The University of Western Ontario; London Ontario Canada
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16
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Shoemaker JK, Badrov MB, Al-Khazraji BK, Jackson DN. Neural Control of Vascular Function in Skeletal Muscle. Compr Physiol 2015; 6:303-29. [PMID: 26756634 DOI: 10.1002/cphy.c150004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The sympathetic nervous system represents a fundamental homeostatic system that exerts considerable control over blood pressure and the distribution of blood flow. This process has been referred to as neurovascular control. Overall, the concept of neurovascular control includes the following elements: efferent postganglionic sympathetic nerve activity, neurotransmitter release, and the end organ response. Each of these elements reflects multiple levels of control that, in turn, affect complex patterns of change in vascular contractile state. Primarily, this review discusses several of these control layers that combine to produce the integrative physiology of reflex vascular control observed in skeletal muscle. Beginning with three reflexes that provide somewhat dissimilar vascular patterns of response despite similar changes in efferent sympathetic nerve activity, namely, the baroreflex, chemoreflex, and muscle metaboreflex, the article discusses the anatomical and physiological bases of postganglionic sympathetic discharge patterns and recruitment, neurotransmitter release and management, and details of regional variations of receptor density and responses within the microvascular bed. Challenges are addressed regarding the fundamentals of measurement and how conclusions from one response or vascular segment should not be used as an indication of neurovascular control as a generalized physiological dogma. Whereas the bulk of the article focuses on the vasoconstrictor function of sympathetic neurovascular integration, attention is also given to the issues of sympathetic vasodilation as well as the impact of chronic changes in sympathetic activation and innervation on vascular health. © 2016 American Physiological Society.
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Affiliation(s)
- J K Shoemaker
- School of Kinesiology, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - M B Badrov
- School of Kinesiology, Western University, London, Ontario, Canada
| | - B K Al-Khazraji
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - D N Jackson
- Department of Medical Biophysics, Western University, London, Ontario, Canada
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17
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Affiliation(s)
- John S Floras
- From University Health Network Divisions of Cardiology and Cardiovascular Surgery and Peter Munk Cardiac Centre, University of Toronto, ON, Canada.
| | - Vivek Rao
- From University Health Network Divisions of Cardiology and Cardiovascular Surgery and Peter Munk Cardiac Centre, University of Toronto, ON, Canada
| | - Filio Billia
- From University Health Network Divisions of Cardiology and Cardiovascular Surgery and Peter Munk Cardiac Centre, University of Toronto, ON, Canada
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18
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Reho JJ, Fisher SA. The stress of maternal separation causes misprogramming in the postnatal maturation of rat resistance arteries. Am J Physiol Heart Circ Physiol 2015; 309:H1468-78. [PMID: 26371173 DOI: 10.1152/ajpheart.00567.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 09/03/2015] [Indexed: 11/22/2022]
Abstract
We examined the effect of stress in the first 2 wk of life induced by brief periods of daily maternal separation on developmental programming of rat small resistance mesenteric arteries (MAs). In MAs of littermate controls, mRNAs encoding mediators of vasoconstriction, including the α1a-adrenergic receptor, smooth muscle myosin heavy chain, and CPI-17, the inhibitory subunit of myosin phosphatase, increased from after birth through sexual [postnatal day (PND) 35] and full maturity, up to ∼80-fold, as measured by quantitative PCR. This was commensurate with two- to fivefold increases in maximum force production to KCl depolarization, calcium, and the α-adrenergic agonist phenylephrine, and increasing systolic blood pressure. Rats exposed to maternal separation stress as neonates had markedly accelerated trajectories of maturation of arterial contractile gene expression and function measured at PND14 or PND21 (weaning), 1 wk after the end of the stress protocol. This was suppressed by the α-adrenergic receptor blocker terazosin (0.5 mg·kg ip(-1)·day(-1)), indicating dependence on stress activation of sympathetic signaling. Due to the continued maturation of MAs in control rats, by sexual maturity (PND35) and into adulthood, no differences were observed in arterial function or response to a second stressor in rats stressed as neonates. Thus early life stress misprograms resistance artery smooth muscle, increasing vasoconstrictor function and blood pressure. This effect wanes in later stages, suggesting plasticity during arterial maturation. Further studies are indicated to determine whether stress in different periods of arterial maturation may cause misprogramming persisting through maturity and the potential salutary effect of α-adrenergic blockade in suppression of this response.
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Affiliation(s)
- John J Reho
- Departments of Medicine (Cardiovascular Medicine) and Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Steven A Fisher
- Departments of Medicine (Cardiovascular Medicine) and Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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