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Dotzert MS, McDonald MW, Olver TD, Sammut MJ, Melling CWJ. The influence of exercise training versus intensive insulin therapy on insulin resistance development in type 1 diabetes. J Diabetes Complications 2023; 37:108365. [PMID: 36463707 DOI: 10.1016/j.jdiacomp.2022.108365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/26/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
The etiology of insulin resistance (IR) in Type 1 Diabetes (T1D) is unclear; however, intramyocellular lipids (IMCL) are likely contributors. While exercise lessens IR and IMCL content; T1D patients elevate glycemia to offset exercise-induced hypoglycemic risk. The preferred treatment for T1D patients is tight glucose management through intensive insulin therapy (IIT); however, IIT is accompanied with a sedentary lifestyle. The purpose of this study was to examine IR development and IMCL in combined exercise (DARE; aerobic/resistance) and IIT-treated T1D animals. 76 rats were divided into control sedentary (C), diabetic sedentary (CD), diabetes sedentary intensive insulin therapy (DIT) and DARE groups. Following streptozotocin (STZ), glycemia was maintained at either 9-15 mM (CD, DARE) or 5-9 mM (DIT) using insulin. DARE alternated between running and weighted climbing for 12 weeks. Results demonstrate that DARE exhibited reduced onset of IR compared with C, DIT and CD, indicated by increased glucose infusion rate (hyperinsulinemic-euglycemic-clamp). A shift in lipid metabolism was evident whereby diacylglycerol was elevated in DIT compared to DARE, while triacylglycerol was elevated in DARE. These findings indicate enhanced IMCL metabolism and the sequestration of fat as neutral triacylglycerol leads to reduced IR in DARE. In contrast, IIT and sedentary behavior leads to diacylglycerol accumulation and IR.
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Affiliation(s)
- Michelle S Dotzert
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, ON, Canada
| | - Matthew W McDonald
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, ON, Canada
| | - T Dylan Olver
- Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Mitchell J Sammut
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, ON, Canada
| | - C W James Melling
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, ON, Canada; Department of Physiology and Pharmacology, Schulich School of Medicine, Western University, London, ON, Canada.
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2
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Olver TD, Grunewald ZI, Ghiarone T, Restaino RM, Sales ARK, Park LK, Thorne PK, Ganga RR, Emter CA, Lemon PWR, Shoemaker JK, Manrique-Acevedo C, Martinez-Lemus LA, Padilla J. Persistent insulin signaling coupled with restricted PI3K activation causes insulin-induced vasoconstriction. Am J Physiol Heart Circ Physiol 2019; 317:H1166-H1172. [PMID: 31603345 DOI: 10.1152/ajpheart.00464.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Insulin modulates vasomotor tone through vasodilator and vasoconstrictor signaling pathways. The purpose of the present work was to determine whether insulin-stimulated vasoconstriction is a pathophysiological phenomenon that can result from a combination of persistent insulin signaling, suppressed phosphatidylinositol-3 kinase (PI3K) activation, and an ensuing relative increase in MAPK/endothelin-1 (ET-1) activity. First, we examined previously published work from our group where we assessed changes in lower-limb blood flow in response to an oral glucose tolerance test (endogenous insulin stimulation) in lean and obese subjects. The new analyses showed that the peak rise in vascular resistance during the postprandial state was greater in obese compared with lean subjects. We next extended on these findings by demonstrating that insulin-induced vasoconstriction in isolated resistance arteries from obese subjects was attenuated with ET-1 receptor antagonism, thus implicating ET-1 signaling in this constriction response. Last, we examined in isolated resistance arteries from pigs the dual roles of persistent insulin signaling and blunted PI3K activation in modulating vasomotor responses to insulin. We found that prolonged insulin stimulation did not alter vasomotor responses to insulin when insulin-signaling pathways remained unrestricted. However, prolonged insulinization along with pharmacological suppression of PI3K activity resulted in insulin-induced vasoconstriction, rather than vasodilation. Notably, such aberrant vascular response was rescued with either MAPK inhibition or ET-1 receptor antagonism. In summary, we demonstrate that insulin-induced vasoconstriction is a pathophysiological phenomenon that can be recapitulated when sustained insulin signaling is coupled with depressed PI3K activation and the concomitant relative increase in MAPK/ET-1 activity.NEW & NOTEWORTHY This study reveals that insulin-induced vasoconstriction is a pathophysiological phenomenon. We also provide evidence that in the setting of persistent insulin signaling, impaired phosphatidylinositol-3 kinase activation appears to be a requisite feature precipitating MAPK/endothelin 1-dependent insulin-induced vasoconstriction.
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Affiliation(s)
- T Dylan Olver
- Department of Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatchewan, Canada
| | - Zachary I Grunewald
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Thaysa Ghiarone
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Robert M Restaino
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.,Department of Health and Human Physiological Sciences, Skidmore College, Saratoga Springs, New York
| | - Allan R K Sales
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.,Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil.,D'Or Institute for Research and Education, São Paulo, Brazil
| | - Lauren K Park
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Pamela K Thorne
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Rama Rao Ganga
- Department of Surgery, University of Missouri, Columbia, Missouri
| | - Craig A Emter
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Peter W R Lemon
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - J Kevin Shoemaker
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Camila Manrique-Acevedo
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.,Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Missouri, Columbia, Missouri.,Research Services, Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri
| | - Luis A Martinez-Lemus
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri.,Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Jaume Padilla
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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Olver TD, Laughlin MH, Padilla J. Exercise and Vascular Insulin Sensitivity in the Skeletal Muscle and Brain. Exerc Sport Sci Rev 2019; 47:66-74. [PMID: 30883470 DOI: 10.1249/jes.0000000000000182] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We present the hypothesis that exercise-induced hyperemia, perhaps through vascular shear stress, represents an important factor responsible for the effects of physical activity (PA) on vascular insulin sensitivity. Specifically, we postulate PA involving the greatest amount of skeletal muscle mass and the greatest central neural recruitment maximizes perfusion and consequently enhances vascular insulin sensitivity in the skeletal muscle and brain.
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Affiliation(s)
- T Dylan Olver
- Department of Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - M Harold Laughlin
- Department of Biomedical Sciences.,Dalton Cardiovascular Research Center
| | - Jaume Padilla
- Dalton Cardiovascular Research Center.,Department of Nutrition and Exercise Physiology, and.,Department of Child Health, University of Missouri, Columbia, MO
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Dotzert MS, Murray MR, McDonald MW, Olver TD, Velenosi TJ, Hennop A, Noble EG, Urquhart BL, Melling CWJ. Metabolomic Response of Skeletal Muscle to Aerobic Exercise Training in Insulin Resistant Type 1 Diabetic Rats. Sci Rep 2016; 6:26379. [PMID: 27197730 PMCID: PMC4873835 DOI: 10.1038/srep26379] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/28/2016] [Indexed: 12/21/2022] Open
Abstract
The etiology of insulin resistance in Type 1 Diabetes (T1D) is unknown, however it affects approximately 20% of T1D patients. Intramyocellular lipids (IMCL) have been identified as a mechanism of insulin resistance. We examined skeletal muscle of T1D rats to determine if alterations in lipid metabolism were evident and whether aerobic exercise training improves IMCL and insulin resistance. To do so, 48 male Sprague-Dawley rats were divided into control (C), sedentary diabetes (D) and diabetes exercise (DX) groups. Following multiple low-dose Streptozotocin (STZ) injections (20 mg/kg), glycemia (9-15 mM) was maintained using insulin treatment. DX were treadmill trained at high intensity (~75% V02max; 5days/week) for 10 weeks. The results demonstrate that D exhibited insulin resistance compared with C and DX, indicated by decreased glucose infusion rate during a hyperinsulinemic-euglycemic clamp (p < 0.05). There were no differences between C and DX, suggesting that exercise improved insulin resistance (p < 0.05). Metabolomics analysis revealed a significant shift in lipid metabolism whereby notable fatty acid metabolites (arachidonic acid, palmitic acid and several polyunsaturated fatty acids) were significantly elevated in D compared to C and DX. Based on the intermediates observed, insulin resistance in T1D is characterized by an insulin-desensitizing intramyocellular fatty acid metabolite profile that is ameliorated with exercise training.
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Affiliation(s)
- Michelle S. Dotzert
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Michael R. Murray
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Matthew W. McDonald
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - T. Dylan Olver
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Thomas J. Velenosi
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Anzel Hennop
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Earl G. Noble
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Brad L. Urquhart
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - C. W. James Melling
- Exercise Biochemistry Laboratory, School of Kinesiology, Western University, London, Ontario, Canada
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Grisé KN, Olver TD, McDonald MW, Dey A, Jiang M, Lacefield JC, Shoemaker JK, Noble EG, Melling CWJ. High Intensity Aerobic Exercise Training Improves Deficits of Cardiovascular Autonomic Function in a Rat Model of Type 1 Diabetes Mellitus with Moderate Hyperglycemia. J Diabetes Res 2016; 2016:8164518. [PMID: 26885531 PMCID: PMC4739461 DOI: 10.1155/2016/8164518] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 02/07/2023] Open
Abstract
Indices of cardiovascular autonomic neuropathy (CAN) in experimental models of Type 1 diabetes mellitus (T1DM) are often contrary to clinical data. Here, we investigated whether a relatable insulin-treated model of T1DM would induce deficits in cardiovascular (CV) autonomic function more reflective of clinical results and if exercise training could prevent those deficits. Sixty-four rats were divided into four groups: sedentary control (C), sedentary T1DM (D), control exercise (CX), or T1DM exercise (DX). Diabetes was induced via multiple low-dose injections of streptozotocin and blood glucose was maintained at moderate hyperglycemia (9-17 mM) through insulin supplementation. Exercise training consisted of daily treadmill running for 10 weeks. Compared to C, D had blunted baroreflex sensitivity, increased vascular sympathetic tone, increased serum neuropeptide Y (NPY), and decreased intrinsic heart rate. In contrast, DX differed from D in all measures of CAN (except NPY), including heart rate variability. These findings demonstrate that this T1DM model elicits deficits and exercise-mediated improvements to CV autonomic function which are reflective of clinical T1DM.
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Affiliation(s)
- Kenneth N. Grisé
- Exercise Biochemistry Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
| | - T. Dylan Olver
- Neurovascular Research Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
| | - Matthew W. McDonald
- Exercise Biochemistry Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
| | - Adwitia Dey
- Exercise Biochemistry Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
| | - Mao Jiang
- Exercise Biochemistry Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
| | - James C. Lacefield
- Department of Electrical and Computer Engineering, Department of Medical Biophysics and Robarts Research Institute, Western University, London, ON, Canada N6A 3K7
| | - J. Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
- Department of Physiology and Pharmacology, Western University, London, ON, Canada N6A 3K7
- Lawson Health Research Institute, London, ON, Canada N6C 2R5
| | - Earl G. Noble
- Exercise Biochemistry Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
- Lawson Health Research Institute, London, ON, Canada N6C 2R5
| | - C. W. James Melling
- Exercise Biochemistry Laboratory, School of Kinesiology, Faculty of Health Sciences, Western University, London, ON, Canada N6A 3K7
- *C. W. James Melling:
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Olver TD, Laughlin MH. Endurance, interval sprint, and resistance exercise training: impact on microvascular dysfunction in type 2 diabetes. Am J Physiol Heart Circ Physiol 2015; 310:H337-50. [PMID: 26408541 DOI: 10.1152/ajpheart.00440.2015] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 09/16/2015] [Indexed: 01/02/2023]
Abstract
Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle, and alters endothelial and vascular smooth muscle cell phenotype, resulting in impaired vasodilatory responses. These changes contribute to altered blood flow responses to physiological stimuli, such as exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and insulin delivery to skeletal muscle (and other tissues such as skin and nervous), thereby reducing glucose uptake and perpetuating hyperglycemia and hyperinsulinemia. In patients with T2D, exercise training (EX) improves microvascular vasodilator and insulin signaling and attenuates capillary rarefaction in skeletal muscle. EX-induced changes subsequently augment glucose and insulin delivery as well as glucose uptake. If these adaptions occur in a sufficient amount of tissue, and skeletal muscle in particular, chronic exposure to hyperglycemia and hyperinsulinemia and the risk of microvascular complications in all vascular beds will decrease. We postulate that EX programs that engage as much skeletal muscle mass as possible and recruit as many muscle fibers within each muscle as possible will generate the greatest improvements in microvascular function, providing that the duration of the stimulus is sufficient. Primary improvements in microvascular function occur in tissues (skeletal muscle primarily) engaged during exercise, and secondary improvements in microvascular function throughout the body may result from improved blood glucose control. We propose that the added benefit of combined resistance and aerobic EX programs and of vigorous intensity EX programs is not simply "more is better." Rather, we believe the additional benefit is the result of EX-induced adaptations in and around more muscle fibers, resulting in more muscle mass and the associated microvasculature being changed. Thus, to acquire primary and secondary improvements in microvascular function and improved blood glucose control, EX programs should involve upper and lower body exercise and modulate intensity to augment skeletal muscle fiber recruitment. Under conditions of limited mobility, it may be necessary to train skeletal muscle groups separately to maximize whole body skeletal muscle fiber recruitment.
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Affiliation(s)
- T Dylan Olver
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri;
| | - M Harold Laughlin
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri; Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
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Xiang L, Mittwede PN, Clemmer JS. Glucose Homeostasis and Cardiovascular Alterations in Diabetes. Compr Physiol 2015; 5:1815-39. [DOI: 10.1002/cphy.c150001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Olver TD, McDonald MW, Grisé KN, Dey A, Allen MD, Medeiros PJ, Lacefield JC, Jackson DN, Rice CL, Melling CWJ, Noble EG, Shoemaker JK. Exercise training enhances insulin-stimulated nerve arterial vasodilation in rats with insulin-treated experimental diabetes. Am J Physiol Regul Integr Comp Physiol 2014; 306:R941-50. [DOI: 10.1152/ajpregu.00508.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin stimulates nerve arterial vasodilation through a nitric oxide (NO) synthase (NOS) mechanism. Experimental diabetes reduces vasa nervorum NO reactivity. Studies investigating hyperglycemia and nerve arterial vasodilation typically omit insulin treatment and use sedentary rats resulting in severe hyperglycemia. We tested the hypotheses that 1) insulin-treated experimental diabetes and inactivity (DS rats) will attenuate insulin-mediated nerve arterial vasodilation, and 2) deficits in vasodilation in DS rats will be overcome by concurrent exercise training (DX rats; 75–85% V̇o2 max, 1 h/day, 5 days/wk, for 10 wk). The baseline index of vascular conductance values (VCi = nerve blood flow velocity/mean arterial blood pressure) were similar ( P ≥ 0.68), but peak VCi and the area under the curve (AUCi) for the VCi during a euglycemic hyperinsulinemic clamp (EHC; 10 mU·kg−1·min−1) were lower in DS rats versus control sedentary (CS) rats and DX rats ( P ≤ 0.01). Motor nerve conduction velocity (MNCV) was lower in DS rats versus CS rats and DX rats ( P ≤ 0.01). When compared with DS rats, DX rats expressed greater nerve endothelial NOS (eNOS) protein content ( P = 0.04). In a separate analysis, we examined the impact of diabetes in exercise-trained rats alone. When compared with exercise-trained control rats (CX), DX rats had a lower AUCi during the EHC, lower MNCV values, and lower sciatic nerve eNOS protein content ( P ≤ 0.03). Therefore, vasa nervorum and motor nerve function are impaired in DS rats. Such deficits in rats with diabetes can be overcome by concurrent exercise training. However, in exercise-trained rats (CX and DX groups), moderate hyperglycemia lowers vasa nervorum and nerve function.
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Affiliation(s)
- T. Dylan Olver
- Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Matthew W. McDonald
- Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Kenneth N. Grisé
- Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Adwitia Dey
- Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Matti D. Allen
- Neuromusclar Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Philip J. Medeiros
- A. C. Burton Laboratory for Vascular Research, Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - James C. Lacefield
- Department of Electrical and Computer Engineering, Department of Medical Biophysics and Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada
| | - Dwayne N. Jackson
- A. C. Burton Laboratory for Vascular Research, Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Charles L. Rice
- Neuromusclar Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; and
| | - C. W. James Melling
- Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Earl G. Noble
- Exercise Biochemistry Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - J. Kevin Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
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Olver DT, Lacefield JC, Shoemaker KJ. Evidence of bidirectional flow in the sciatic vasa nervorum. Microvasc Res 2014; 94:103-5. [PMID: 24909900 DOI: 10.1016/j.mvr.2014.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 05/27/2014] [Accepted: 05/29/2014] [Indexed: 12/13/2022]
Abstract
The purpose of this study was to determine whether bidirectional flow exists in the sciatic vasa nervorum. Images obtained using high-frequency color Doppler ultrasound in duplex imaging mode (Vevo 2100) were studied retroactively. In Fig. 1 (left panel; rat 1), the color Doppler signal and flow-velocity waveforms are indicative of pulsatile flow traveling towards (B) and away (C) from the probe. In the right panel (Fig. 1; rat 2), there appears to be three distinct vessels, reflective of non-pulsatile negative flow (D), and pulsatile positive (E) and negative (F) flows. These data confirm the presence of bidirectional arterial flow in the sciatic vasa nervorum. Investigating bidirectional flow in the intact whole nerve may be helpful in elucidating novel features of nerve blood flow control in healthy and diseased states.
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Affiliation(s)
- Dylan T Olver
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario N6A 3K7, Canada.
| | - James C Lacefield
- Department of Electrical and Computer Engineering, Department of Medical Biophysics and Robarts Research Institute, Western University, London, Ontario N6A 3K7, Canada.
| | - Kevin J Shoemaker
- Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario N6A 3K7, Canada; Department of Physiology and Pharmacology, Western University, London, Ontario N6A 3K7, Canada.
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