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Carter KJ, Ward AT, Al-Subu A, Wilson AD, Zevin EL, Serlin RC, Eldridge M, Wieben O, Schrage WG. An oral glucose tolerance test does not affect cerebral blood flow: role of NOS. Am J Physiol Regul Integr Comp Physiol 2023; 325:R759-R768. [PMID: 37842740 DOI: 10.1152/ajpregu.00169.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 09/11/2023] [Accepted: 10/06/2023] [Indexed: 10/17/2023]
Abstract
Animal data indicate that insulin triggers a robust nitric oxide synthase (NOS)-mediated dilation in cerebral arteries similar to the peripheral tissue vasodilation observed in healthy adults. Insulin's role in regulating cerebral blood flow (CBF) in humans remains unclear but may be important for understanding the links between insulin resistance, diminished CBF, and poor brain health outcomes. We tested the hypothesis that an oral glucose challenge (oral glucose tolerance test, OGTT), which increases systemic insulin and glucose, would acutely increase CBF in healthy adults due to NOS-mediated vasodilation, and that changes in CBF would be greater in anterior regions where NOS expression or activity may be greater. In a randomized, single-blind approach, 18 young healthy adults (24 ± 5 yr) underwent magnetic resonance imaging (MRI) with a placebo before and after an OGTT (75 g glucose), and 11 of these adults also completed an NG-monomethyl-l-arginine (l-NMMA) visit. Four-dimensional (4-D) flow MRI quantified macrovascular CBF and arterial spin labeling (ASL) quantified microvascular perfusion. Subjects completed baseline imaging with a placebo (or l-NMMA), then consumed an OGTT followed by MRI scans and blood sampling every 10-15 min for 90 min. Contrary to our hypothesis, total CBF (P = 0.17) and global perfusion (P > 0.05) did not change at any time point up to 60 min after the OGTT, and no regional changes were detected. l-NMMA did not mediate any effect of OGTT on CBF. These data suggest that insulin-glucose challenge does not acutely alter CBF in healthy adults.
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Affiliation(s)
- Katrina J Carter
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
| | - Aaron T Ward
- Deparment of Center for Health Disparities Research, University of Wisconsin, Madison, Wisconsin, United States
| | - Awni Al-Subu
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Allen D Wilson
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Erika L Zevin
- Department of Pediatrics, University School of Medicine, Indianapolis, Indiana, United States
| | - Ronald C Serlin
- Department of Educational Psychology, University of Wisconsin, Madison, Wisconsin, United States
| | - Marlowe Eldridge
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, United States
- Department of Radiology, University of Wisconsin, Madison, Wisconsin, United States
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
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2
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Carr JMJR, Hoiland RL, Fernandes IA, Schrage WG, Ainslie PN. Recent insights into mechanisms of hypoxia-induced vasodilatation in the human brain. J Physiol 2023. [PMID: 37655827 DOI: 10.1113/jp284608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/07/2023] [Indexed: 09/02/2023] Open
Abstract
The cerebral vasculature manages oxygen delivery by adjusting arterial blood in-flow in the face of reductions in oxygen availability. Hypoxic cerebral vasodilatation, and the associated hypoxic cerebral blood flow reactivity, involve many vascular, erythrocytic and cerebral tissue mechanisms that mediate elevations in cerebral blood flow via micro- and macrovascular dilatation. This contemporary review focuses on in vivo human work - with reference to seminal preclinical work where necessary - on hypoxic cerebrovascular reactivity, particularly where recent advancements have been made. We provide updates with the following information: in humans, hypoxic cerebral vasodilatation is partially mediated via a - likely non-obligatory - combination of: (1) nitric oxide synthases, (2) deoxygenation-coupled S-nitrosothiols, (3) potassium channel-related vascular smooth muscle hyperpolarization, and (4) prostaglandin mechanisms with some contribution from an interrelationship with reactive oxygen species. And finally, we discuss the fact that, due to the engagement of deoxyhaemoglobin-related mechanisms, reductions in O2 content via haemoglobin per se seem to account for ∼50% of that seen with hypoxic cerebral vasodilatation during hypoxaemia. We further highlight the issue that methodological impediments challenge the complete elucidation of hypoxic cerebral reactivity mechanisms in vivo in healthy humans. Future research is needed to confirm recent advancements and to reconcile human and animal findings. Further investigations are also required to extend these findings to address questions of sex-, heredity-, age-, and disease-related differences. The final step is to then ultimately translate understanding of these mechanisms into actionable, targetable pathways for the prevention and treatment of cerebral vascular dysfunction and cerebral hypoxic brain injury.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for Researching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Igor A Fernandes
- Department of Health and Kinesiology, Purdue University, Indiana, USA
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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3
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Carter KJ, Ward AT, Kellawan JM, Harrell JW, Peltonen GL, Roberts GS, Al-Subu A, Hagen SA, Serlin RC, Eldridge MW, Wieben O, Schrage WG. Reduced basal macrovascular and microvascular cerebral blood flow in young adults with metabolic syndrome: potential mechanisms. J Appl Physiol (1985) 2023; 135:94-108. [PMID: 37199780 PMCID: PMC10292973 DOI: 10.1152/japplphysiol.00688.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 04/26/2023] [Accepted: 05/13/2023] [Indexed: 05/19/2023] Open
Abstract
Ninety-million Americans suffer metabolic syndrome (MetSyn), increasing the risk of diabetes and poor brain outcomes, including neuropathology linked to lower cerebral blood flow (CBF), predominantly in anterior regions. We tested the hypothesis that total and regional CBF is lower in MetSyn more so in the anterior brain and explored three potential mechanisms. Thirty-four controls (25 ± 5 yr) and 19 MetSyn (30 ± 9 yr), with no history of cardiovascular disease/medications, underwent four-dimensional flow magnetic resonance imaging (MRI) to quantify macrovascular CBF, whereas arterial spin labeling quantified brain perfusion in a subset (n = 38/53). Contributions of cyclooxygenase (COX; n = 14), nitric oxide synthase (NOS, n = 17), or endothelin receptor A signaling (n = 13) were tested with indomethacin, NG-monomethyl-L-arginine (L-NMMA), and Ambrisentan, respectively. Total CBF was 20 ± 16% lower in MetSyn (725 ± 116 vs. 582 ± 119 mL/min, P < 0.001). Anterior and posterior brain regions were 17 ± 18% and 30 ± 24% lower in MetSyn; reductions were not different between regions (P = 0.112). Global perfusion was 16 ± 14% lower in MetSyn (44 ± 7 vs. 36 ± 5 mL/100 g/min, P = 0.002) and regionally in frontal, occipital, parietal, and temporal lobes (range 15-22%). The decrease in CBF with L-NMMA (P = 0.004) was not different between groups (P = 0.244, n = 14, 3), and Ambrisentan had no effect on either group (P = 0.165, n = 9, 4). Interestingly, indomethacin reduced CBF more in Controls in the anterior brain (P = 0.041), but CBF decrease in posterior was not different between groups (P = 0.151, n = 8, 6). These data indicate that adults with MetSyn exhibit substantially reduced brain perfusion without regional differences. Moreover, this reduction is not due to loss of NOS or gain of ET-1 signaling but rather a loss of COX vasodilation.NEW & NOTEWORTHY We tested the impact of insulin resistance (IR) on resting cerebral blood flow (CBF) in adults with metabolic syndrome (MetSyn). Using MRI and research pharmaceuticals to study the role of NOS, ET-1, or COX signaling, we found that adults with MetSyn exhibit substantially lower CBF that is not explained by changes in NOS or ET-1 signaling. Interestingly, adults with MetSyn show a loss of COX-mediated vasodilation in the anterior but not posterior circulation.
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Affiliation(s)
- Katrina J Carter
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
| | - Aaron T Ward
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
| | - J Mikhail Kellawan
- Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma, United States
| | - John W Harrell
- 711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio, United States
| | - Garrett L Peltonen
- School of Nursing and Kinesiology, Western New Mexico University, Silver City, New Mexico, United States
| | - Grant S Roberts
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, United States
| | - Awni Al-Subu
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Scott A Hagen
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Ronald C Serlin
- Department of Educational Psychology, University of Wisconsin, Madison, Wisconsin, United States
| | - Marlowe W Eldridge
- Department of Pediatrics, University of Wisconsin, Madison, Wisconsin, United States
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, United States
- Department of Radiology, University of Wisconsin, Madison, Wisconsin, United States
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin, United States
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Muer JD, Didier KD, Wannebo BM, Carter KJ, Hagen SA, Eldridge M, Al‐Subu AM, Livett TA, Wieben O, Schrage WG. The impact of cyclooxygenase inhibition with ketorolac on regional cerebral perfusion in healthy adults. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r5748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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5
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Spaude K, Ward AT, Brubaker JM, Zevin EL, Livett TA, Carrel AM, Schrage WG. Do Adolescents With Insulin Resistance Demonstrate Impaired Heart Rate Recovery From Exercise? FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r6258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Katie Spaude
- KinesiologyUniversity of Wisconsin‐MadisonMadisonWI
| | | | | | - Erika L. Zevin
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Timothy A. Livett
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Aaron M. Carrel
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
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Didier KD, Muer JD, Wannebo BM, Carter KJ, Hagen SA, Eldridge MW, Al‐Subu AM, Livett TA, Wieben O, Schrage WG. Effect of Cyclooxygenase Inhibitor on Hypoxia Stimulated Cerebral Blood Flow Using Arterial Spin Labeling Magnetic Resonance. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.0r879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - Scott A. Hagen
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Marlowe W. Eldridge
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Awni M. Al‐Subu
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Timothy A. Livett
- PediatricsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Oliver Wieben
- Medical PhysicsUniversity of Wisconsin School of Medicine and Public HealthMadisonWI
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Limberg JK, Johansson RE, Carter KJ, Peltonen GL, Harrell JW, Kellawan JM, Eldridge MW, Sebranek JJ, Walker BJ, Schrage WG. Preserved β-adrenergic-mediated vasodilation in skeletal muscle of young adults with obesity despite shifts in cyclooxygenase and nitric oxide synthase. Am J Physiol Heart Circ Physiol 2022; 322:H25-H35. [PMID: 34738833 PMCID: PMC8698505 DOI: 10.1152/ajpheart.00449.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults. Because β-AR vasodilation in normal weight adults is limited by cyclooxygenase (COX) restraint of nitric oxide synthase (NOS), we further explored the contributions of COX and NOS to β-AR vasodilation in this cohort. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured and forearm vascular conductance (FVC) was calculated (FVC = FBF/MAP). The rise in FVC from baseline (ΔFVC) was quantified during graded brachial artery infusion of isoproterenol (Iso, 1-12 ng/100 g/min) in normal weight (n = 36) and adults with obesity (n = 22) (18-40 yr old). In a subset of participants, Iso-mediated vasodilation was examined before and during inhibition of NOS [NG-monomethyl-l-arginine (l-NMMA)], COX (ketorolac), and NOS + COX (l-NMMA + ketorolac). Iso-mediated increases in FVC did not differ between groups (P = 0.57). l-NMMA attenuated Iso-mediated ΔFVC in normal weight (P = 0.03) but not adults with obesity (P = 0.27). In normal weight adults, ketorolac increased Iso-mediated ΔFVC (P < 0.01) and this response was lost with concurrent l-NMMA (P = 0.67). In contrast, neither ketorolac (P = 0.81) nor ketorolac + l-NMMA (P = 0.40) altered Iso-mediated ΔFVC in adults with obesity. Despite shifts in COX and NOS, β-AR vasodilation is preserved in young adults with obesity. These data highlight the presence of a compensatory shift in microvascular control mechanisms in younger humans with obesity.NEW & NOTEWORTHY We examined β-adrenergic receptor-mediated vasodilation in skeletal muscle of humans with obesity and normal weight. Results show that despite shifts in the contribution of cyclooxygenase and nitric oxide synthase, β-adrenergic-mediated vasodilation is relatively preserved in young, otherwise healthy adults with obesity. These data highlight the presence of subclinical changes in microvascular control mechanisms early in the obesity process and suggest duration of obesity and/or the addition of primary aging may be necessary for overt dysfunction.
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Affiliation(s)
- Jacqueline K. Limberg
- 1Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri,2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | | | - Katrina J. Carter
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | - Garrett L. Peltonen
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,3School of Nursing and Kinesiology, Western New Mexico University, Silver City, New Mexico
| | - John W. Harrell
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,4711th Human Performance Wing, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio
| | - J. Mikhail Kellawan
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,5Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma
| | - Marlowe W. Eldridge
- 2Department of Kinesiology, University of Wisconsin, Madison, Wisconsin,6Department of Pediatrics, University of Wisconsin, Madison, Wisconsin
| | - Joshua J. Sebranek
- 7Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
| | - Benjamin J. Walker
- 7Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
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Carter KJ, Ward AT, Kellawan JM, Eldridge MW, Al-Subu A, Walker BJ, Lee JW, Wieben O, Schrage WG. Nitric oxide synthase inhibition in healthy adults reduces regional and total cerebral macrovascular blood flow and microvascular perfusion. J Physiol 2021; 599:4973-4989. [PMID: 34587648 PMCID: PMC9009720 DOI: 10.1113/jp281975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 09/28/2021] [Indexed: 11/08/2022] Open
Abstract
The importance of nitric oxide (NO) in regulating cerebral blood flow (CBF) remains unresolved, due in part to methodological approaches, which lack a comprehensive assessment of both global and regional effects. Importantly, NO synthase (NOS) expression and activity appear greater in some anterior brain regions, suggesting region-specific NOS influence on CBF. We hypothesized that NO contributes to basal CBF in healthy adults, in a regionally distinct pattern that predominates in the anterior circulation. Fourteen healthy adults (7 females; 24 ± 5 years) underwent two magnetic resonance imaging (MRI) study visits with saline (placebo) or the NOS inhibitor, L-NMMA, administered in a randomized, single-blind approach. 4D flow MRI quantified total and regional macrovascular CBF, whereas arterial spin labelling (ASL) MRI quantified total and regional microvascular perfusion. L-NMMA (or volume-matched saline) was infused intravenously for 5 min prior to imaging. L-NMMA reduced CBF (L-NMMA: 722 ± 100 vs. placebo: 771 ± 121 ml/min, P = 0.01) with similar relative reductions (5-7%) in anterior and posterior cerebral circulations, due in part to the reduced cross-sectional area of 9 of 11 large cerebral arteries. Global microvascular perfusion (ASL) was reduced by L-NMMA (L-NMMA: 42 ± 7 vs. placebo: 47 ± 8 ml/100g/min, P = 0.02), with 7-11% reductions in both hemispheres of the frontal, parietal and temporal lobes, and in the left occipital lobe. We conclude that NO contributes to macrovascular and microvascular regulation including larger artery resting diameter. Contrary to our hypothesis, the influence of NO on cerebral perfusion appears regionally uniform in healthy young adults. KEY POINTS: Cerebral blood flow (CBF) is vital for brain health, but the signals that are key to regulating CBF remain unclear. Nitric oxide (NO) is produced in the brain, but its importance in regulating CBF remains controversial since prior studies have not studied all regions of the brain simultaneously. Using modern MRI approaches, a drug that inhibits the enzymes that make NO (L-NMMA) reduced CBF by up to 11% in different brain regions. NO helps maintain proper CBF in healthy adults. These data will help us understand whether the reductions in CBF that occur during ageing or cardiovascular disease are related to shifts in NO signalling.
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Affiliation(s)
- Katrina J Carter
- Department of Kinesiology, University of Wisconsin, Madison, WI, USA
| | - Aaron T Ward
- Department of Kinesiology, University of Wisconsin, Madison, WI, USA
| | - J Mikhail Kellawan
- Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA
| | | | - Awni Al-Subu
- Department of Pediatrics, University of Wisconsin, Madison, WI, USA
| | - Benjamin J Walker
- Department of Anesthesiology, University of Wisconsin, Madison, WI, USA
| | - Jeffrey W Lee
- Department of Anesthesiology, University of Wisconsin, Madison, WI, USA
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
- Department of Radiology, University of Wisconsin, Madison, WI, USA
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, WI, USA
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Brubaker JM, Carter KJ, Ward AT, Kellawan JM, Harrell JW, Eldridge MW, Roldan A, Wieben O, Schrage WG. Does Hypoxia Affect Pulse Transit Time in Healthy Controls? FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Muer JD, Ward AT, Carter KJ, Kellawan JM, Harrell JW, Roldan A, Wieben O, Eldridge MW, Schrage WG. Does insulin resistance alter pulse transit time in the cerebral circulation? FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Carter KJ, Ward AT, Bolin SE, Eldridge MW, Hagen SA, Walker BJ, Lee JW, al-Subu AM, Wieben O, Schrage WG. Role of Endothelin‐1 in Regulating Basal Macrovascular Cerebral Blood Flow: Healthy versus Metabolic Syndrome. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Ward AT, Carter KJ, Bolin SE, Eldridge MW, Hagen SA, Walker BJ, Lee JW, al-Subu AM, Wieben O, Schrage WG. Endothelin Receptor Antagonism Increases Cerebral Perfusion in Humans. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.05858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Kellawan JM, Peltonen GL, Harrell JW, Roldan-Alzate A, Wieben O, Schrage WG. Differential contribution of cyclooxygenase to basal cerebral blood flow and hypoxic cerebral vasodilation. Am J Physiol Regul Integr Comp Physiol 2019; 318:R468-R479. [PMID: 31868517 DOI: 10.1152/ajpregu.00132.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cyclooxygenase (COX) is proposed to regulate cerebral blood flow (CBF); however, accurate regional contributions of COX are relatively unknown at baseline and particularly during hypoxia. We hypothesized that COX contributes to both basal and hypoxic cerebral vasodilation, but COX-mediated vasodilation is greater in the posterior versus anterior cerebral circulation. CBF was measured in 9 healthy adults (28 ± 4 yr) during normoxia and isocapnic hypoxia (fraction of inspired oxygen = 0.11), with COX inhibition (oral indomethacin, 100mg) or placebo. Four-dimensional flow magnetic resonance imaging measured cross-sectional area (CSA) and blood velocity to quantify CBF in 11 cerebral arteries. Cerebrovascular conductance (CVC) was calculated (CVC = CBF × 100/mean arterial blood pressure) and hypoxic reactivity was expressed as absolute and relative change in CVC [ΔCVC/Δ pulse oximetry oxygen saturation (SpO2)]. At normoxic baseline, indomethacin reduced CVC by 44 ± 5% (P < 0.001) and artery CSA (P < 0.001), which was similar across arteries. Hypoxia (SpO2 80%-83%) increased CVC (P < 0.01), reflected as a similar relative increase in reactivity (% ΔCVC/-ΔSpO2) across arteries (P < 0.05), in part because of increases in CSA (P < 0.05). Indomethacin did not alter ΔCVC or ΔCVC/ΔSpO2 to hypoxia. These findings indicate that 1) COX contributes, in a largely uniform fashion, to cerebrovascular tone during normoxia and 2) COX is not obligatory for hypoxic vasodilation in any regions supplied by large extracranial or intracranial arteries.
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Affiliation(s)
- J Mikhail Kellawan
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin.,Department of Health and Exercise Science, University of Oklahoma, Norman, OK
| | - Garrett L Peltonen
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin.,Department of Kinesiology, Western New Mexico University, Silver City, New Mexico
| | - John W Harrell
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | - Alejandro Roldan-Alzate
- Department of Radiology, University of Wisconsin, Madison, Wisconsin.,Department of Mechanical Engineering, University of Wisconsin, Madison, Wisconsin
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
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14
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Harrell JW, Peltonen GL, Schrage WG. Reactive oxygen species and cyclooxygenase products explain the majority of hypoxic cerebral vasodilation in healthy humans. Acta Physiol (Oxf) 2019; 226:e13288. [PMID: 31033206 DOI: 10.1111/apha.13288] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 03/14/2019] [Accepted: 04/23/2019] [Indexed: 12/13/2022]
Abstract
AIM The role of reactive oxygen species (ROS) in human cerebral blood flow (CBF) during hypoxia is largely unknown. Additionally, it is unknown whether ROS interact with cyclooxygenase-derived signals during hypoxia to increase CBF. We hypothesized ROS inhibition would reduce hypoxic CBF, and combined inhibition of cyclooxygenase (COX) and ROS would decrease hypoxic CBF more than ROS suppression alone. METHODS We measured middle cerebral artery velocity with transcranial Doppler ultrasound in 12 healthy adults during normoxia and 2 isocapnic hypoxia trials. Intravenous ascorbic acid infusion during the first hypoxia trial suppressed ROS. Oral indomethacin inhibited COX between hypoxia trials. The second bout of hypoxia tested the combined effects of ROS and COX inhibition. Middle cerebral artery velocity was normalized for blood pressure as cerebrovascular conductance index. RESULTS Hypoxia increased cerebrovascular conductance index in both trials (P < 0.05). Ascorbic acid infusion did not alter cerebrovascular conductance index during hypoxia. Combined ascorbic acid and indomethacin significantly reduced hypoxia-mediated increases in cerebrovascular conductance index from 17 ± 2 to 4 ± 1 cm s-1 100 mm Hg-1 (P < 0.05). CONCLUSION ROS are not obligatory for hypoxic cerebral vasodilation. Current data indicate ROS and COX together may account for the majority of the increase in CBF through the middle cerebral artery during hypoxia. These data are the first to demonstrate compensatory hypoxic vasodilatory signalling in human cerebral circulation.
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Affiliation(s)
- John W. Harrell
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology University of Wisconsin‐Madison Madison Wisconsin
| | - Garrett L. Peltonen
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology University of Wisconsin‐Madison Madison Wisconsin
- Department of Kinesiology Western New Mexico University Silver City New Mexico
| | - William G. Schrage
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology University of Wisconsin‐Madison Madison Wisconsin
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Affiliation(s)
- Jacqueline K Limberg
- 1Department of Anesthesiology, Mayo Clinic, Rochester, MN; and Departments of 2Kinesiology and 3Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI
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Carter KJ, Kellawan JM, Ward AT, Johansson RE, Harrell JW, Peltonen GL, Sauder CJ, Eldridge MW, Schrage WG. Does obesity differentially impact male and female responses to skeletal muscle vasodilation during exercise? FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.722.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - J Mikhail Kellawan
- KinesiologyUniversity of Wisconsin‐MadisonMadisonWI
- Health and Exercise ScienceUniversity of OklahomaNormanOK
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17
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Sauder CJ, Carter KJ, Ward AT, Morgan BJ, Hagen EW, Peppard P, Schrage WG. Cerebrovascular Reactivity in Obstructive Sleep Apnea: Impact of Physical Activity. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.712.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Barbara J. Morgan
- Orthopedics and RehabilitationUniversity of Wisconsin‐MadisonMadisonWI
| | - Erika W. Hagen
- Population Health SciencesUniversity of Wisconsin‐MadisonMadisonWI
| | - Paul Peppard
- Population Health SciencesUniversity of Wisconsin‐MadisonMadisonWI
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18
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Ward AT, Carter KJ, Sauder CJ, Kellawan JM, Weiben O, Schrage WG. Cerebrovascular Regulation During an Insulin‐Glucose Challenge: Contribution of Nitric Oxide. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.712.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - J. Mikhail Kellawan
- KinesiologyUniversity of Wisconsin‐MadisonMadisonWI
- Health and Exercise ScienceUniversity of OklahomaNormanOK
| | - Oliver Weiben
- Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWI
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19
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Kellawan JM, Limberg JK, Scruggs ZM, Nicholson WT, Schrage WG, Joyner MJ, Curry TB. Phosphodiesterase-5 inhibition preserves exercise-onset vasodilator kinetics when NOS activity is reduced. J Appl Physiol (1985) 2017; 124:276-282. [PMID: 28982942 DOI: 10.1152/japplphysiol.00483.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nitric oxide (NO)-mediated vasodilation contributes to the rapid rise in muscle blood flow at exercise onset. This occurs via increased cyclic guanosine monophosphate (cGMP), which is catabolized by phosphodiesterase-5 (PDE-5). Whether PDE-5 limits exercise vasodilation onset kinetics is unknown. We hypothesized the time course of exercise vasodilation would be 1) accelerated during PDE-5 inhibition (sildenafil citrate, SDF) and 2) decelerated during NO synthase inhibition ( NG-monomethyl-l-arginine, l-NMMA), and 3) the effect of SDF on vasodilation onset kinetics would be attenuated with concurrent l-NMMA. Data from 29 healthy adults were analyzed. Individuals completed 5 min of moderate-intensity forearm exercise under control conditions and during 1) oral SDF ( n = 8), 2) intra-arterial l-NMMA ( n = 15), or 3) combined SDF + l-NMMA ( n = 6). Forearm blood flow (FBF; Doppler ultrasound of the brachial artery) and mean brachial artery blood pressure (MAP) were measured continuously. Forearm vascular conductance (FVC, FBF ÷ MAP) was curve-fit with a monoexponential model, and vasodilation onset kinetics were assessed by mean response time (MRT, time to achieve 63% of steady state). SDF had no effect on MRT ( P = 0.90). NOS inhibition increased MRT ( P = 0.01). MRT during SDF+l-NMMA was not different from control exercise ( P = 0.76). PDE-5 inhibition alone has no effect on rapid-onset vasodilation. Whereas NOS inhibition decelerates vasodilator kinetics, when combined with SDF, vasodilator kinetics do not differ from control. These data suggest NO-independent activation of cGMP occurs at exercise onset; thus PDE-5 inhibition may improve vasodilation in pathologies where NO bioavailability is impaired. NEW & NOTEWORTHY We show that when NO bioavailability is reduced, PDE-5 inhibition can restore vasodilation onset kinetics of exercise-mediated vasodilation via NO-independent cGMP pathways. These data suggest PDE-5 inhibition may improve exercise vasodilation onset kinetics in pathologies where NO bioavailability is impaired.
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Affiliation(s)
- J Mikhail Kellawan
- Department of Kinesiology, University of Wisconsin , Madison, Wisconsin.,Department of Health and Exercise Science, University of Oklahoma , Norman, Oklahoma
| | - Jacqueline K Limberg
- Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Zachariah M Scruggs
- Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Wayne T Nicholson
- Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin , Madison, Wisconsin.,Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Michael J Joyner
- Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
| | - Timothy B Curry
- Department of Anesthesiology, Mayo Clinic College of Medicine , Rochester, Minnesota
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20
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Mikhail Kellawan J, Harrell JW, Roldan-Alzate A, Wieben O, Schrage WG. Regional hypoxic cerebral vasodilation facilitated by diameter changes primarily in anterior versus posterior circulation. J Cereb Blood Flow Metab 2017; 37:2025-2034. [PMID: 27406213 PMCID: PMC5464698 DOI: 10.1177/0271678x16659497] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The inability to quantify cerebral blood flow and changes in macrocirculation cross-sectional area in all brain regions impedes robust insight into hypoxic cerebral blood flow control. We applied four-dimensional flow magnetic resonance imaging to quantify cerebral blood flow (ml • min-1) and cross-sectional area (mm2) simultaneously in 11 arteries. In healthy adults, blood pressure, O2 Saturation (SpO2), and end-tidal CO2 were measured at baseline and steady-state hypoxia (FiO2 = 0.11). We investigated left and right: internal carotid, vertebral, middle, anterior, posterior cerebral arteries, and basilar artery. Hypoxia (SpO2 = 80±2%) increased total cerebral blood flow from 621±38 to 742±50 ml • min-1 ( p < 0.05). Hypoxia increased cerebral blood flow, except in the right posterior cerebral arteries. Hypoxia increased cross-sectional area in the anterior arteries (left and right internal carotid arteries, left and right middle, p < 0.05; left and right anterior p = 0.08) but only the right vertebral artery of the posterior circulation. Nonetheless, relative cerebral blood flow distribution and vascular reactivity (Δ%cerebral blood flow • ΔSpO2-1) were not different between arteries. Collectively, moderate hypoxia: (1) increased cerebral blood flow, but relative distribution remains similar to normoxia, (2) evokes similar vascular reactivity between 11 arteries, and (3) increased cross-sectional area primarily in the anterior arteries. This study provides the first wide-ranging, quantitative, functional and structural data regarding intracranial arteries during hypoxia in humans, highlighting cerebral blood flow regulation of microcirculation and macrocirculation differs between anterior and posterior circulation.
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Affiliation(s)
- J Mikhail Kellawan
- 1 Departments of Kinesiology, University of Wisconsin - Madison, WI, USA
| | - John W Harrell
- 1 Departments of Kinesiology, University of Wisconsin - Madison, WI, USA
| | - Alejandro Roldan-Alzate
- 2 Departments of Medical Physics, University of Wisconsin - Madison, WI, USA.,3 Departments of Radiology, University of Wisconsin - Madison, WI, USA
| | - Oliver Wieben
- 2 Departments of Medical Physics, University of Wisconsin - Madison, WI, USA.,3 Departments of Radiology, University of Wisconsin - Madison, WI, USA
| | - William G Schrage
- 1 Departments of Kinesiology, University of Wisconsin - Madison, WI, USA
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21
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Hoscheidt SM, Kellawan JM, Berman SE, Rivera-Rivera LA, Krause RA, Oh JM, Beeri MS, Rowley HA, Wieben O, Carlsson CM, Asthana S, Johnson SC, Schrage WG, Bendlin BB. Insulin resistance is associated with lower arterial blood flow and reduced cortical perfusion in cognitively asymptomatic middle-aged adults. J Cereb Blood Flow Metab 2017; 37:2249-2261. [PMID: 27488909 PMCID: PMC5464714 DOI: 10.1177/0271678x16663214] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Insulin resistance (IR) is associated with poor cerebrovascular health and increased risk for dementia. Little is known about the unique effect of IR on both micro- and macrovascular flow particularly in midlife when interventions against dementia may be most effective. We examined the effect of IR as indexed by the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) on cerebral blood flow in macro- and microvessels utilizing magnetic resonance imaging (MRI) among cognitively asymptomatic middle-aged individuals. We hypothesized that higher HOMA-IR would be associated with reduced flow in macrovessels and lower cortical perfusion. One hundred and twenty cognitively asymptomatic middle-aged adults (57 ± 5 yrs) underwent fasting blood draw, phase contrast-vastly undersampled isotropic projection reconstruction (PC VIPR) MRI, and arterial spin labeling (ASL) perfusion. Higher HOMA-IR was associated with lower arterial blood flow, particularly within the internal carotid arteries (ICAs), and lower cerebral perfusion in several brain regions including frontal and temporal lobe regions. Higher blood flow in bilateral ICAs predicted greater cortical perfusion in individuals with lower HOMA-IR, a relationship not observed among those with higher HOMA-IR. Findings provide novel evidence for an uncoupling of macrovascular blood flow and microvascular perfusion among individuals with higher IR in midlife.
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Affiliation(s)
- Siobhan M Hoscheidt
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | | | - Sara E Berman
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Leonardo A Rivera-Rivera
- 3 Department of Medical Physics, University of Wisconsin, Madison, WI, USA.,4 Department of Radiology, University of Wisconsin, Madison, WI, USA
| | - Rachel A Krause
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Jennifer M Oh
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Michal S Beeri
- 5 The Joseph Sagol Neuroscience Center, Sheba Medical Center, Israel.,6 The Icahn School of Medicine, Mount Sinai, NY, USA
| | - Howard A Rowley
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,4 Department of Radiology, University of Wisconsin, Madison, WI, USA
| | - Oliver Wieben
- 3 Department of Medical Physics, University of Wisconsin, Madison, WI, USA.,4 Department of Radiology, University of Wisconsin, Madison, WI, USA
| | - Cynthia M Carlsson
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,7 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI, USA.,8 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Sanjay Asthana
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,7 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI, USA.,8 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Sterling C Johnson
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,7 Geriatric Research Education and Clinical Center, Wm. S. Middleton Veterans Hospital, Madison, WI, USA.,8 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - William G Schrage
- 2 Department of Kinesiology, University of Wisconsin, Madison, WI, USA
| | - Barbara B Bendlin
- 1 Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.,8 Wisconsin Alzheimer's Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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22
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Carter KJ, Kellawan JM, Peltonen GL, Ward AT, Carrel AL, Wieben O, Bendlin BB, Schrage WG. Regional Patterns of Pulsatility Index and Wall Shear Stress Across Cerebral Circulation of Adolescents with High Insulin Resistance. FASEB J 2017. [DOI: 10.1096/fasebj.31.1_supplement.836.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | - Oliver Wieben
- Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWI
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23
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Limberg JK, Peltonen GL, Johansson RE, Harrell JW, Kellawan JM, Eldridge MW, Sebranek JJ, Walker BJ, Schrage WG. Greater Beta-Adrenergic Receptor Mediated Vasodilation in Women Using Oral Contraceptives. Front Physiol 2016; 7:215. [PMID: 27375493 PMCID: PMC4896959 DOI: 10.3389/fphys.2016.00215] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/23/2016] [Indexed: 11/25/2022] Open
Abstract
Background: β-adrenergic receptors play an important role in mitigating the pressor effects of sympathetic nervous system activity in young women. Based on recent data showing oral contraceptive use in women abolishes the relationship between muscle sympathetic nervous system activity and blood pressure, we hypothesized forearm blood flow responses to a β-adrenergic receptor agonist would be greater in young women currently using oral contraceptives (OC+, n = 13) when compared to those not using oral contraceptives (OC–, n = 10). Methods: Women (18–35 years) were studied during the early follicular phase of the menstrual cycle (days 1–5) or placebo phase of oral contraceptive use. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured at baseline and during graded brachial artery infusion of the β-adrenergic receptor agonist, Isoproterenol (ISO), as well as Acetylcholine (ACH, endothelium-dependent vasodilation) and Nitroprusside (NTP, endothelium-independent vasodilation). Forearm vascular conductance was calculated (FVC = FBF/MAP, ml/min/100 mmHg) and the rise in FVC from baseline during infusion quantified vasodilation (ΔFVC = FVCinfusion − FVCbaseline). Results: ISO increased FVC in both groups (p < 0.01) and ISO-mediated ΔFVC was greater in OC+ compared to OC– (Main effect of group, p = 0.02). Expressing data as FVC and FBF resulted in similar conclusions. FVC responses to both ACH and NTP were also greater in OC+ compared to OC–. Conclusions: These data are the first to demonstrate greater β-adrenergic receptor-mediated vasodilation in the forearm of women currently using oral contraceptives (placebo phase) when compared to those not using oral contraceptives (early follicular phase), and suggest oral contraceptive use influences neurovascular control.
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Affiliation(s)
| | | | | | - John W Harrell
- Department of Kinesiology, University of Wisconsin Madison, WI, USA
| | | | - Marlowe W Eldridge
- Department of Kinesiology, University of WisconsinMadison, WI, USA; Department of Pediatrics, University of WisconsinMadison, WI, USA
| | - Joshua J Sebranek
- Department of Anesthesiology, University of Wisconsin Madison, WI, USA
| | - Benjamin J Walker
- Department of Anesthesiology, University of Wisconsin Madison, WI, USA
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24
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Peltonen GL, Harrell JW, Aleckson BP, LaPlante KM, Crain MK, Schrage WG. Cerebral blood flow regulation in women across menstrual phase: differential contribution of cyclooxygenase to basal, hypoxic, and hypercapnic vascular tone. Am J Physiol Regul Integr Comp Physiol 2016; 311:R222-31. [PMID: 27225949 DOI: 10.1152/ajpregu.00106.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 05/24/2016] [Indexed: 11/22/2022]
Abstract
In healthy young women, basal cerebral blood flow (CBF) and cerebrovascular reactivity may change across the menstrual cycle, but mechanisms remain untested. When compared with the early follicular phase of the menstrual cycle, we hypothesized women in late follicular phase would exhibit: 1) greater basal CBF, 2) greater hypercapnic increases in CBF, 3) greater hypoxic increases in CBF, and 4) increased cyclooxygenase (COX) signaling. We measured middle cerebral artery velocity (MCAv, transcranial Doppler ultrasound) in 11 healthy women (23 ± 1 yr) during rest, hypoxia, and hypercapnia. Subjects completed four visits: two during the early follicular (∼day 3) and two during the late follicular (∼day 14) phases of the menstrual cycle, with and without COX inhibition (oral indomethacin). Isocapnic hypoxia elicited an SPO2 = 90% and SPO2 = 80% for 5 min each. Separately, hypercapnia increased end-tidal CO2 10 mmHg above baseline. Cerebral vascular conductance index (CVCi = MCAv/MABP·100, where MABP is mean arterial blood pressure) was calculated and a positive change reflected vasodilation (ΔCVCi). Basal CVCi was greater in the late follicular phase (P < 0.001). Indomethacin decreased basal CVCi (∼37%) and abolished the phase difference (P < 0.001). Hypoxic ΔCVCi was similar between phases and unaffected by indomethacin. Hypercapnic ΔCVCi was similar between phases, and indomethacin decreased hypercapnic ΔCVCi (∼68%; P < 0.001) similarly between phases. In summary, while neither hypercapnic nor hypoxic vasodilation is altered by menstrual phase, increased basal CBF in the late follicular phase is fully explained by a greater contribution of COX. These data provide new mechanistic insight into anterior CBF regulation across menstrual phases and contribute to our understanding of CBF regulation in women.
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Affiliation(s)
- Garrett L Peltonen
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - John W Harrell
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Benjamin P Aleckson
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Kaylie M LaPlante
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Meghan K Crain
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - William G Schrage
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
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25
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Mikhail Kellawan J, Harrell JW, Schrauben EM, Hoffman CA, Roldan-Alzate A, Schrage WG, Wieben O. Quantitative cerebrovascular 4D flow MRI at rest and during hypercapnia challenge. Magn Reson Imaging 2016; 34:422-8. [DOI: 10.1016/j.mri.2015.12.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/13/2015] [Indexed: 12/01/2022]
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26
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Limberg JK, Johansson RE, Peltonen GL, Harrell JW, Kellawan JM, Eldridge MW, Sebranek JJ, Schrage WG. β-Adrenergic-mediated vasodilation in young men and women: cyclooxygenase restrains nitric oxide synthase. Am J Physiol Heart Circ Physiol 2016; 310:H756-64. [PMID: 26747505 DOI: 10.1152/ajpheart.00886.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/06/2016] [Indexed: 01/22/2023]
Abstract
We tested the hypothesis that women exhibit greater vasodilator responses to β-adrenoceptor stimulation compared with men. We further hypothesized women exhibit a greater contribution of nitric oxide synthase and cyclooxygenase to β-adrenergic-mediated vasodilation compared with men. Forearm blood flow (Doppler ultrasound) was measured in young men (n = 29, 26 ± 1 yr) and women (n = 33, 25 ± 1 yr) during intra-arterial infusion of isoproterenol (β-adrenergic agonist). In subset of subjects, isoproterenol responses were examined before and after local inhibition of nitric oxide synthase [N(G)-monomethyl-l-arginine (l-NMMA); 6 male/10 female] and/or cyclooxygenase (ketorolac; 5 male/5 female). Vascular conductance (blood flow ÷ mean arterial pressure) was calculated to assess vasodilation. Vascular conductance increased with isoproterenol infusion (P < 0.01), and this effect was not different between men and women (P = 0.41). l-NMMA infusion had no effect on isoproterenol-mediated dilation in men (P > 0.99) or women (P = 0.21). In contrast, ketorolac infusion markedly increased isoproterenol-mediated responses in both men (P < 0.01) and women (P = 0.04) and this rise was lost with subsequent l-NMMA infusion (men, P < 0.01; women, P < 0.05). β-Adrenergic vasodilation is not different between men and women and sex differences in the independent contribution of nitric oxide synthase and cyclooxygenase to β-mediated vasodilation are not present. However, these data are the first to demonstrate β-adrenoceptor activation of cyclooxygenase suppresses nitric oxide synthase signaling in human forearm microcirculation and may have important implications for neurovascular control in both health and disease.
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Affiliation(s)
| | | | | | - John W Harrell
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | | | - Marlowe W Eldridge
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin; Department of Pediatrics, University of Wisconsin, Madison, Wisconsin; and
| | - Joshua J Sebranek
- Department of Anesthesiology, University of Wisconsin, Madison, Wisconsin
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin;
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27
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Harrell JW, Johansson RE, Evans TD, Sebranek JJ, Walker BJ, Eldridge MW, Serlin RC, Schrage WG. Preserved Microvascular Endothelial Function in Young, Obese Adults with Functional Loss of Nitric Oxide Signaling. Front Physiol 2015; 6:387. [PMID: 26733880 PMCID: PMC4686588 DOI: 10.3389/fphys.2015.00387] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 11/30/2015] [Indexed: 01/04/2023] Open
Abstract
Data indicate endothelium-dependent dilation (EDD) may be preserved in the skeletal muscle microcirculation of young, obese adults. Preserved EDD might be mediated by compensatory mechanisms, impeding insight into preclinical vascular dysfunction. We aimed to determine the functional roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) toward EDD in younger obese adults. We first hypothesized EDD would be preserved in young, obese adults. Further, we hypothesized a reduced contribution of NOS in young, obese adults would be replaced by increased COX signaling. Microvascular EDD was assessed with Doppler ultrasound and brachial artery infusion of acetylcholine (ACh) in younger (27 ± 1 year) obese (n = 29) and lean (n = 46) humans. Individual and combined contributions of NOS and COX were examined with intra-arterial infusions of l-NMMA and ketorolac, respectively. Vasodilation was quantified as an increase in forearm vascular conductance (ΔFVC). Arterial endothelial cell biopsies were analyzed for protein expression of endothelial nitric oxide synthase (eNOS). ΔFVC to ACh was similar between groups. After l-NMMA, ΔFVC to ACh was greater in obese adults (p < 0.05). There were no group differences in ΔFVC to ACh with ketorolac. With combined NOS-COX inhibition, ΔFVC was greater in obese adults at the intermediate dose of ACh. Surprisingly, arterial endothelial cell eNOS and phosphorylated eNOS were similar between groups. Younger obese adults exhibit preserved EDD and eNOS expression despite functional dissociation of NOS-mediated vasodilation and similar COX signaling. Compensatory NOS- and COX-independent vasodilatory mechanisms conceal reduced NOS contributions in otherwise healthy obese adults early in life, which may contribute to vascular dysfunction.
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Affiliation(s)
- John W Harrell
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison Madison, WI, USA
| | - Rebecca E Johansson
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison Madison, WI, USA
| | - Trent D Evans
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison Madison, WI, USA
| | - Joshua J Sebranek
- Department of Anesthesiology, University of Wisconsin Hospital and Clinics, University of Wisconsin-Madison Madison, WI, USA
| | - Benjamin J Walker
- Department of Anesthesiology, University of Wisconsin Hospital and Clinics, University of Wisconsin-Madison Madison, WI, USA
| | - Marlowe W Eldridge
- The John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin-MadisonMadison, WI, USA; Department of Pediatrics, University of Wisconsin Hospital and Clinics, University of Wisconsin-MadisonMadison, WI, USA
| | - Ronald C Serlin
- Department of Educational Psychology, University of Wisconsin-Madison Madison, WI, USA
| | - William G Schrage
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison Madison, WI, USA
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28
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Peltonen GL, Harrell JW, Rousseau CL, Ernst BS, Marino ML, Crain MK, Schrage WG. Cerebrovascular regulation in men and women: stimulus-specific role of cyclooxygenase. Physiol Rep 2015; 3:3/7/e12451. [PMID: 26149282 PMCID: PMC4552531 DOI: 10.14814/phy2.12451] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Greater cerebral artery vasodilation mediated by cyclooxygenase (COX) in female animals is unexplored in humans. We hypothesized that young, healthy women would exhibit greater basal cerebral blood flow (CBF) and greater vasodilation during hypoxia or hypercapnia compared to men, mediated by a larger contribution of COX. We measured middle cerebral artery velocity (MCAv, transcranial Doppler ultrasound) in 42 adults (24 women, 18 men; 24 ± 1 years) during two visits, in a double-blind, placebo-controlled design (COX inhibition, 100 mg oral indomethacin, Indo). Women were studied early in the follicular phase of the menstrual cycle (days 1–5). Two levels of isocapnic hypoxia (SPO2 = 90% and 80%) were induced for 5-min each. Separately, hypercapnia was induced by increasing end-tidal carbon dioxide (PETCO2) 10 mmHg above baseline. A positive change in MCAv (ΔMCAv) reflected vasodilation. Basal MCAv was greater in women compared to men (P < 0.01) across all conditions. Indo decreased baseline MCAv (P < 0.01) similarly between sexes. Hypoxia increased MCAv (P < 0.01), but ΔMCAv was not different between sexes. Indo did not alter hypoxic vasodilation in either sex. Hypercapnia increased MCAv (P < 0.01), but ΔMCAv was not different between sexes. Indo elicited a large decrease in hypercapnic vasodilation (P < 0.01) that was similar between sexes. During the early follicular phase, women exhibit greater basal CBF than men, but similar vasodilatory responses to hypoxia and hypercapnia. Moreover, COX is not obligatory for hypoxic vasodilation, but plays a vital and similar role in the regulation of basal CBF (∼30%) and hypercapnic response (∼55%) between sexes.
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Affiliation(s)
- Garrett L Peltonen
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - John W Harrell
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Cameron L Rousseau
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Brady S Ernst
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Mariah L Marino
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - Meghan K Crain
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
| | - William G Schrage
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
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Limberg JK, Kellawan JM, Harrell JW, Johansson RE, Eldridge MW, Proctor LT, Sebranek JJ, Schrage WG. Exercise-mediated vasodilation in human obesity and metabolic syndrome: effect of acute ascorbic acid infusion. Am J Physiol Heart Circ Physiol 2014; 307:H840-7. [PMID: 25038148 DOI: 10.1152/ajpheart.00312.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that infusion of ascorbic acid (AA), a potent antioxidant, would alter vasodilator responses to exercise in human obesity and metabolic syndrome (MetSyn). Forearm blood flow (FBF, Doppler ultrasound) was measured in lean, obese, and MetSyn adults (n = 39, 32 ± 2 yr). A brachial artery catheter was inserted for blood pressure monitoring and local infusion of AA. FBF was measured during dynamic handgrip exercise (15% maximal effort) with and without AA infusion. To account for group differences in blood pressure and forearm size, and to assess vasodilation, forearm vascular conductance (FVC = FBF/mean arterial blood pressure/lean forearm mass) was calculated. We examined the time to achieve steady-state FVC (mean response time, MRT) and the rise in FVC from rest to steady-state exercise (Δ, exercise - rest) before and during acute AA infusion. The MRT (P = 0.26) and steady-state vasodilator responses to exercise (ΔFVC, P = 0.31) were not different between groups. Intra-arterial infusion of AA resulted in a significant increase in plasma total antioxidant capacity (174 ± 37%). AA infusion did not alter MRT or steady-state FVC in any group (P = 0.90 and P = 0.85, respectively). Interestingly, higher levels of C-reactive protein predicted longer MRT (r = 0.52, P < 0.01) and a greater reduction in MRT with AA infusion (r = -0.43, P = 0.02). We concluded that AA infusion during moderate-intensity, rhythmic forearm exercise does not alter the time course or magnitude of exercise-mediated vasodilation in groups of young lean, obese, or MetSyn adults. However, systemic inflammation may limit the MRT to exercise, which can be improved with AA.
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Affiliation(s)
| | - J Mikhail Kellawan
- Department of Kinesiology, School of Education, University of Wisconsin, and
| | - John W Harrell
- Department of Kinesiology, School of Education, University of Wisconsin, and
| | - Rebecca E Johansson
- Department of Kinesiology, School of Education, University of Wisconsin, and
| | | | - Lester T Proctor
- Anesthesiology, School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, Wisconsin
| | - Joshua J Sebranek
- Anesthesiology, School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, Wisconsin
| | - William G Schrage
- Department of Kinesiology, School of Education, University of Wisconsin, and
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Du S, Joyner MJ, Curry TB, Eisenach JH, Johnson CP, Schrage WG, Jensen MD. Effect of β2-adrenergic receptor polymorphisms on epinephrine and exercise-stimulated lipolysis in humans. Physiol Rep 2014; 2:2/5/e12017. [PMID: 24844639 PMCID: PMC4098745 DOI: 10.14814/phy2.12017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The β2‐adrenergic system is an important regulator of human adipose tissue lipolysis. Polymorphisms that result in amino acid substitutions in the β2‐adrenergic receptor have been reported to alter lipolysis. We hypothesized that variations in the amino acid at position 16 of the β2‐adrenergic receptor would result in different lipolytic responses to intravenous epinephrine and exercise. 17 volunteers homozygous for glycine at position 16 (Gly/Gly, nine female) and 16 volunteers homozygous for arginine at position 16 (Arg/Arg, eight female) of the β2‐adrenergic receptor participated in this study. On one study day participants received infusions of epinephrine at submaximal (5 ng kg−1 min−1) and maximal (40 ng kg−1 min−1) lipolytic doses. The other study day volunteers bicycled for 90 min at 50–60% of maximum oxygen consumption (VO2max). [9,10‐3H] Palmitate was infused both days to measure free fatty acid – palmitate kinetics. Oxygen consumption was measured using indirect calorimetry. Palmitate release rates in response to epinephrine and exercise were not different in the Gly/Gly and Arg/Arg participants. The only statistically significant difference we observed was a lesser ΔVO2 in Arg/Arg volunteers in response to the submaximal epinephrine infusion. The polymorphisms resulting in Arg/Arg and Gly/Gly at position 16 of the β2‐adrenergic receptor do not result in clinically meaningful differences in lipolysis responses to epinephrine or submaximal exercise. e12017 Some studies suggest the polymorphism in the β2‐adrenergic receptor have effects on fatty acid mobilization from adipose tissue. We measure lipolysis using tracer kinetics in volunteers selected for different genotypes at position 16 of the β2‐adrenergic receptor. We found that polymorphisms resulting in Arg/Arg and Gly/Gly at position 16 of the β2‐adrenergic receptor do not result in clinically meaningful differences in lipolysis responses to epinephrine or submaximal exercise.
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Affiliation(s)
- Shichun Du
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | | | | | | | | | - William G Schrage
- Anesthesiology Research, Mayo Clinic, Rochester, Minnesota Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
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Limberg JK, Morgan BJ, Sebranek JJ, Proctor LT, Eldridge MW, Schrage WG. Neural control of blood flow during exercise in human metabolic syndrome. Exp Physiol 2014; 99:1191-202. [PMID: 24659613 DOI: 10.1113/expphysiol.2014.078048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
α-Adrenergic-mediated vasoconstriction is greater during simulated exercise in animal models of metabolic syndrome (MetSyn) when compared with control animals. In an attempt to translate such findings to humans, we hypothesized that adults with MetSyn (n = 14, 35 ± 3 years old) would exhibit greater α-adrenergic responsiveness during exercise when compared with age-matched healthy control subjects (n = 16, 31 ± 3 years old). We measured muscle sympathetic nerve activity (MSNA; microneurography) and forearm blood flow (Doppler ultrasound) during dynamic forearm exercise (15% of maximal voluntary contraction). α-Adrenergic agonists (phenylephrine and clonidine) and an antagonist (phentolamine) were infused intra-arterially to assess α-adrenergic receptor responsiveness and restraint, respectively. Resting MSNA was ∼35% higher in adults with MetSyn (P < 0.05), but did not change in either group with dynamic exercise. Clonidine-mediated vasoconstriction was greater in adults with MetSyn (P < 0.01). Group differences in vascular responses to phenylephrine and phentolamine were not detected (P > 0.05). Interestingly, exercise-mediated vasodilatation was greater in MetSyn (P < 0.05). Adults with MetSyn exhibit greater resting MSNA and clonidine-mediated vasoconstriction, yet preserved functional sympatholysis and higher exercise blood flow during low-intensity hand-grip exercise when compared with age-matched healthy control subjects. These results suggest that adults with MetSyn exhibit compensatory vascular control mechanisms capable of preserving blood flow responses to exercise in the face of augmented sympathetic adrenergic activity.
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Affiliation(s)
- Jacqueline K Limberg
- School of Education, Department of Kinesiology, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Barbara J Morgan
- School of Medicine and Public Health, Department of Orthopedics and Rehabilitation, University of Wisconsin - Madison, Madison, WI 53706, USA
| | - Joshua J Sebranek
- School of Medicine and Public Health, Department of Anesthesiology, University of Wisconsin - Madison, Madison, WI 53792, USA
| | - Lester T Proctor
- School of Medicine and Public Health, Department of Anesthesiology, University of Wisconsin - Madison, Madison, WI 53792, USA
| | - Marlowe W Eldridge
- School of Medicine and Public Health, Department of Pediatrics, University of Wisconsin - Madison, Madison, WI 53792, USA
| | - William G Schrage
- School of Education, Department of Kinesiology, University of Wisconsin - Madison, Madison, WI 53706, USA
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Limberg JK, Johansson RE, McBride PE, Schrage WG. Increased leg blood flow and improved femoral artery shear patterns in metabolic syndrome after a diet and exercise programme. Clin Physiol Funct Imaging 2013; 34:282-9. [PMID: 24237709 DOI: 10.1111/cpf.12095] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 10/01/2013] [Indexed: 01/10/2023]
Abstract
BACKGROUND Altered vascular shear profiles may contribute to the development of atherosclerosis. Physical activity promotes anti-atherogenic shear patterns, resulting in reduced cardiovascular disease risk. Adults with metabolic syndrome (MetSyn) are at increased risk of developing atherosclerosis and cardiovascular disease. Thus, we hypothesized that conduit artery antegrade shear rate (ASR) would increase and retrograde shear rate (RSR) and oscillatory shear indices (OSI) would decrease in MetSyn patients (n = 16, 51 ± 2 years) after participation in a diet and exercise programme (DEP). METHODS Blood flow (Doppler ultrasound, brachial and femoral arteries) was measured, and shear rates were calculated in MetSyn patients before and after 12 weeks of DEP participation. In addition, plasma samples were collected to measure atherogenic markers. RESULTS Diet and exercise programme participation increased resting leg blood flow and femoral artery ASR (P ≤ 0·05), and tended to decrease OSI (P = 0·09); RSR did not change (P>0·05). No changes in resting arm blood flow or ASR were observed (P>0·05), and both RSR and OSI increased after participation (P≤0·05). DEP participation reduced plasma vascular cell adhesion molecule(VCAM)-1 (P = 0·03), with a trend for reduced intercellular cell adhesion molecule(ICAM)-1 (P = 0·09) (i.e. atherogenic markers). CONCLUSION Modest changes in diet and physical activity result in limb-specific improvements in vascular shear profiles and reduced systemic markers of atherosclerotic risk in MetSyn patients. These data provide novel physiologic insight into adaptations that may limit the progression of atherosclerosis in patients with MetSyn.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Kinesiology, School of Education, University of Wisconsin - Madison, Madison, WI, USA
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Harrell JW, Schrage WG. Cyclooxygenase-derived vasoconstriction restrains hypoxia-mediated cerebral vasodilation in young adults with metabolic syndrome. Am J Physiol Heart Circ Physiol 2013; 306:H261-9. [PMID: 24213610 DOI: 10.1152/ajpheart.00709.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Poor cerebrovascular function in metabolic syndrome (MetSyn) likely contributes to elevated risk of cerebrovascular disease in this growing clinical population. Younger MetSyn adults without clinical evidence of cerebrovascular disease exhibit preserved hypercapnic vasodilation yet markedly impaired hypoxic vasodilation, but the mechanisms behind reduced hypoxic vasodilation are unknown. Based on data from rats, we tested the hypothesis that younger adults with MetSyn exhibit reduced cerebral hypoxic vasodilation due to loss of vasodilating prostaglandins. Middle cerebral artery velocity (MCAv) was measured with transcranial Doppler ultrasound in adults with MetSyn (n = 13, 33 ± 3 yr) and healthy controls (n = 15, 31 ± 2 yr). Isocapnic hypoxia was induced by titrating inspired oxygen to lower arterial saturation to 90% and 80% for 5 min each. Separately, hypercapnia was induced by increasing end-tidal CO2 10 mmHg above baseline levels. Cyclooxygenase inhibition (100 mg indomethacin) was conducted in a randomized double-blind, placebo controlled design. MCAv was normalized for group differences in blood pressure (healthy: 89 ± 2 mmHg vs. MetSyn: 102 ± 2 mmHg) as cerebrovascular conductance index (CVCi), and used to assess cerebral vasodilation. Hypoxia increased CVCi in both groups; however, vasodilation was ∼55% lower in MetSyn at SpO2 = 80% (P < 0.05). Indomethacin tended to decrease hypoxic vasodilation in healthy controls, and unexpectedly increased dilation in MetSyn (P < 0.05). In contrast to hypoxia, hypercapnia-mediated vasodilation was similar between groups, as was the decrease in vasodilation with indomethacin. These data indicate increased production of vasoconstrictor prostaglandins restrains hypoxic cerebral vasodilation in MetSyn, preventing them from responding appropriately to this important physiological stressor.
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Affiliation(s)
- John W Harrell
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin
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Limberg JK, Harrell JW, Johansson RE, Eldridge MW, Proctor LT, Sebranek JJ, Schrage WG. Microvascular function in younger adults with obesity and metabolic syndrome: role of oxidative stress. Am J Physiol Heart Circ Physiol 2013; 305:H1230-7. [PMID: 23934859 DOI: 10.1152/ajpheart.00291.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Older adults with cardiovascular disease exhibit microvascular dysfunction and increased levels of reactive oxygen species (ROS). We hypothesized that microvascular impairments begin early in the disease process and can be improved by scavenging ROS. Forearm blood flow (Doppler ultrasound) was measured in 45 young (32 ± 2 yr old) adults (n = 15/group) classified as lean, obese, and metabolic syndrome (MetSyn). Vasodilation in response to endothelial (ACh) and vascular smooth muscle [nitroprusside (NTP) and epoprostenol (Epo)] agonists was tested before and after intra-arterial infusion of ascorbic acid to scavenge ROS. Vasodilation was assessed as a rise in relative vascular conductance (ml·min(-1)·dl(-1)·100 mmHg(-1)). ACh and NTP responses were preserved (P = 0.825 and P = 0.924, respectively), whereas Epo responses were lower in obese and MetSyn adults (P < 0.05) than in lean controls. Scavenging of ROS via infusion of ascorbic acid resulted in an increase in ACh-mediated (P < 0.001) and NTP-mediated (P < 0.001) relative vascular conductance across all groups, suggesting that oxidative stress influences vascular responsiveness in adults with and without overt cardiovascular disease risk. Ascorbic acid had no effect on Epo-mediated vasodilation (P = 0.267). These results suggest that obese and MetSyn adults exhibit preserved endothelium-dependent vasodilation with reduced dependence on prostacyclin and are consistent with an upregulation of compensatory vascular control mechanisms.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Kinesiology, School of Education, University of Wisconsin, Madison, Wisconsin
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Limberg JK, Morgan BJ, Schrage WG, Dempsey JA. Respiratory influences on muscle sympathetic nerve activity and vascular conductance in the steady state. Am J Physiol Heart Circ Physiol 2013; 304:H1615-23. [PMID: 23585141 DOI: 10.1152/ajpheart.00112.2013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In patients with hypertension, volitional slowing of the respiratory rate has been purported to reduce arterial pressure via withdrawal of sympathetic tone. We examined the effects of paced breathing at 7, 14, and 21 breaths/min, with reciprocal changes in tidal volume, on muscle sympathetic nerve activity, forearm blood flow, forearm vascular conductance, and blood pressure in 21 men and women, 8 of whom had modest elevations in systemic arterial pressure. These alterations in breathing frequency and volume did not affect steady-state levels of sympathetic activity, blood flow, vascular conductance, or blood pressure (all P > 0.05), even though they had the expected effect on sympathetic activity within breaths (i.e., increased modulation during low-frequency/high-tidal volume breathing) (P < 0.001). These findings were consistent across subjects with widely varied baseline levels of sympathetic activity (4-fold), mean arterial pressure (78-110 mmHg), and vascular conductance (15-fold), and those who became hypocapnic during paced breathing vs. those who maintained normocapnia. These findings challenge the notion that slow, deep breathing lowers arterial pressure by suppressing steady-state sympathetic outflow.
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Affiliation(s)
- Jacqueline K Limberg
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, School of Education, University of Wisconsin, Madison, WI, USA
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Johansson RE, Harrell JW, Limberg JK, Crain MK, Rousseau CL, Yanke PA, Sebranek JJ, Walker BJ, Eldridge MW, Schrage WG. Contributions of nitric oxide and prostaglandins to exercise hyperemia in young obese adults. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1136.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | | | - Joshua J Sebranek
- School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI
| | - Benjamin J Walker
- School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI
| | - Marlowe W Eldridge
- School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI
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Crain MK, Johansson RE, Peltonen GL, Harrell JW, Schrage WG, Limberg JK, Sebranek JJ, Walker BJ, Eldridge MW. Reduced contribution of NOS and CO to beta adrenergic vasodilation in obesity. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1133.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | | | - Joshua J Sebranek
- University of Wisconsin School of Medicine and Public HealthMadisonWI
| | - Benjamin J Walker
- University of Wisconsin School of Medicine and Public HealthMadisonWI
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Limberg JK, Morgan BJ, Schrage WG, Dempsey JA. Respiratory influences on muscle sympathetic nerve activity and limb vascular conductance in the steady‐state. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1118.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jacqueline K Limberg
- School of EducationDepartment of KinesiologyUniversity of Wisconsin ‐ MadisonMadisonWI
| | - Barbara J Morgan
- School of Medicine and Public HealthDepartment of Orthopedics and RehabilitationUniversity of Wisconsin ‐ MadisonMadisonWI
- School of Medicine and Public HealthJohn Rankin Laboratory of Pulmonary MedicineUniversity of Wisconsin ‐ MadisonMadisonWI
| | - William G Schrage
- School of EducationDepartment of KinesiologyUniversity of Wisconsin ‐ MadisonMadisonWI
| | - Jerome A Dempsey
- School of Medicine and Public HealthJohn Rankin Laboratory of Pulmonary MedicineUniversity of Wisconsin ‐ MadisonMadisonWI
- School of Medicine and Public HealthDepartment of Population Health SciencesUniversity of Wisconsin ‐ MadisonMadisonWI
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Lee Peltonen G, Johansson RE, Harrell JW, Limberg JK, Crain MK, Sebranek JJ, Walker BJ, Marlowe EW, Schrage WG. Endothelium dependent vasodilation in young, obese adults: contribution of NOS. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1133.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Harrell JW, Yanke PA, Schrage WG. Metabolic Syndrome alters the balance of prostaglandins in hypoxia‐mediated cerebral vasodilation. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1203.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- John W Harrell
- Department of KinesiologyUniversity of Wisconsin‐MadisonMadisonWI
| | - Peter A Yanke
- School of Medicine and Public HealthUniversity of Wisconsin‐MadisonMadisonWI
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Abstract
Metabolic syndrome (MetSyn) increases the risk of cerebrovascular disease and stroke; however, its impact on human cerebral circulation remains unclear. Reduced cerebral dilation is also associated with an increased risk of stroke and may occur in MetSyn adults. We hypothesised that MetSyn adults would exhibit reduced cerebral vasodilation to hypoxia and hypercapnia. Middle cerebral artery velocity (MCAv) was insonated with Doppler ultrasound in younger (approximately 35 years) MetSyn and healthy adults. We measured mean arterial blood pressure (MABP), arterial oxygen saturation (S(p)O(2)) and end tidal carbon dioxide (Pet (CO2)). Cerebrovascular conductance index (CVCi) was calculated as MCAv*100/MABP. Cerebral vasodilation (ΔCVCi) to hypoxia (S(p)O(2) = 90% and 80%) and hypercapnia (+10 mm Hg Pet (CO2)) was assessed. Baseline MCAv was similar, while adults with MetSyn had lower baseline CVCi. MetSyn adults demonstrated markedly reduced ΔCVCi compared to healthy adults in response to hypoxia (90% S(p)O(2): 1±2 vs 6±2; 80% S(p)O(2): 5±2 vs 15±3 cm/s/mmHg, p<0.05). Both groups demonstrated similar ΔCVCi to hypercapnia (18±2 vs 20±2 cm/s/mmHg). These data are the first to demonstrate that younger MetSyn adults have impaired hypoxia-mediated cerebral vasodilation prior to clinically overt cerebrovascular disease. These findings provide novel insight into cerebrovascular disease onset in MetSyn adults.
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Affiliation(s)
| | - Barbara J Morgan
- Department of Orthopedics and Rehabilitation, University of Wisconsin, USA
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Limberg JK, Morgan BJ, Sebranek JJ, Proctor LT, Walker BJ, Eldridge MW, Schrage WG. Altered neurovascular control of the resting circulation in human metabolic syndrome. J Physiol 2012; 590:6109-19. [PMID: 23027821 DOI: 10.1113/jphysiol.2012.239780] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Young healthy adults exhibit an inverse linear relationship between muscle sympathetic nerve activity (MSNA) and α-adrenergic responsiveness. This balance may be reversed in metabolic syndrome (MetSyn) as animal models exhibit increased sympathetic activity and α-mediated vasoconstriction. We hypothesized humans with MetSyn would demonstrate increased α-adrenergic vasoconstriction and the inverse relationship between MSNA and adrenergic responsiveness would be lost. We measured MSNA (microneurography of the peroneal nerve) and forearm blood flow (FBF, Doppler ultrasound) in 16 healthy control subjects (31 ± 3 years) and 14 adults with MetSyn (35 ± 3 years; P > 0.05) during local administration of α-adrenergic agonists (phenylephrine (PE), α(1); clonidine (CL), α(2)). MSNA was greater in MetSyn subjects than in healthy controls (P < 0.05). A group difference in vasoconstriction to PE was not detected (P = 0.08). The level of α(1)-mediated vasoconstriction was inversely related to MSNA in control subjects (r = 0.5, P = 0.04); this balance between MSNA and α(1) responsiveness was lost in adults with MetSyn. MetSyn subjects exhibited greater vasoconstriction to CL infusion as compared with healthy controls (P < 0.01). A relationship between MSNA and α(2)-mediated vasoconstriction was not detected in either group. In summary, altered neurovascular control in human MetSyn is receptor specific. The observed uncoupling between MSNA and α(1)-adrenergic responsiveness and increased α(2) vasoconstriction may lead to reduced FBF, altered flow distribution, and/or severe hypertension with the progression toward diabetes and cardiovascular disease.
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Affiliation(s)
- Jacqueline K Limberg
- School of Education, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI 53076, USA
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Abstract
AIM Conduit artery function in obese humans is frequently assessed at rest, but very little is known about resistance artery function in response to muscle contraction. We tested the hypothesis that obese adults will exhibit reduced contraction-induced rapid onset vasodilatation. Single and brief forearm contractions were used to isolate the local effects of muscle contraction on the forearm vasodilatory response, independent of systemic haemodynamic and sympathetic neural influence. METHODS We measured forearm blood flow (Doppler ultrasound), blood pressure (finger photoplethysmography) and heart rate (electrocardiogram) on a beat-by-beat basis in 14 obese (body mass index = 36.2 ± 1.7 kg m(-2)) and 14 lean (body mass index = 21.6 ± 0.7 kg m(-2)) young (18-40 years) adults. Percent changes from baseline in forearm vascular conductance (FVC(%) ) were calculated in response to single, brief forearm contractions performed in random order at 15, 20, 25, 30, 40 and 50% of maximal voluntary contraction (MVC). RESULTS In both groups, each single contraction evoked a significant (P < 0.05), immediate (within one cardiac cycle) and graded FVC(%) increase from one up to six cardiac cycles post-contraction. Immediate (20-50% MVC), peak (15-50% MVC) and total (area under the curve, 20-50% MVC) vasodilatory responses were reduced with obesity. The degree of impaired vasodilatation increased with increasing workloads. CONCLUSIONS These novel findings demonstrate a blunted contraction-induced rapid onset vasodilatation with obesity that is exercise intensity dependent. Impaired rapid onset vasodilatation may negatively impact haemodynamic responses to everyday intermittent activities performed by obese humans.
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Affiliation(s)
- G M Blain
- Department of Population Health Sciences, The John Rankin Laboratory of Pulmonary Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, USA
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Johansson RE, Limberg JK, McBride PE, Schrage WG. Can diabetes prevention program increase resting leg blood flow and antegrade shear rate in patients with metabolic syndrome? FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1142.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Patrick E McBride
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
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Limberg JK, McKenna EJ, Sebranek JJ, Walker BJ, Hagen SA, Morgan BJ, Schrage WG. Augmented alpha‐adrenergic vasoconstriction during exercise in human metabolic syndrome. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1092.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Joshua J Sebranek
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
| | - Benjamin J Walker
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
| | - Scott A Hagen
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
| | - Barbara J Morgan
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
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Harrell JW, McKenna EJ, Linstroth LA, Morgan BJ, Schrage WG. Stimulus‐specific cerebrovascular dysfunction in humans with metabolic syndrome. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.896.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- John W Harrell
- Department of KinesiologyUniversity of Wisconsin - MadisonMadisonWI
| | - Edward J McKenna
- Department of KinesiologyUniversity of Wisconsin - MadisonMadisonWI
| | - Lee A Linstroth
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
| | - Barbara J Morgan
- School of Medicine and Public HealthUniversity of Wisconsin - MadisonMadisonWI
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Limberg JK, Evans TD, Blain GM, Pegelow DF, Danielson JR, Eldridge MW, Proctor LT, Sebranek JJ, Schrage WG. Effect of obesity and metabolic syndrome on hypoxic vasodilation. Eur J Appl Physiol 2011; 112:699-709. [PMID: 21656228 DOI: 10.1007/s00421-011-2025-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 05/23/2011] [Indexed: 12/30/2022]
Abstract
This study was designed to test whether obese adults and adults with metabolic syndrome (MetSyn) exhibit altered hyperemic responses to hypoxia at rest and during forearm exercise when compared with lean controls. We hypothesized blood flow responses due to hypoxia would be lower in young obese subjects (n = 11, 24 ± 2 years, BMI 36 ± 2 kg m(-2)) and subjects with MetSyn (n = 8, 29 ± 3 years BMI 39 ± 2 kg m(-2)) when compared with lean adults (n = 13, 29 ± 2 years, BMI 24 ± 1 kg m(-2)). We measured forearm blood flow (FBF, Doppler Ultrasound) and arterial oxygen saturation (pulse oximetry) during rest and steady-state dynamic forearm exercise (20 contractions/min at 8 and 12 kg) under two conditions: normoxia (0.21 F(i)O(2), ~98% S(a)O(2)) and hypoxia (~0.10 F(i)O(2), 80% S(a)O(2)). Forearm vascular conductance (FVC) was calculated as FBF/mean arterial blood pressure. At rest, the percent change in FVC with hypoxia was greater in adults with MetSyn when compared with lean controls (p = 0.02); obese and lean adult responses were not statistically different. Exercise increased FVC from resting levels in all groups (p < 0.05). Hypoxia caused an additional increase in FVC (p < 0.05) that was not different between groups; responses to hypoxia were heterogeneous within and between groups. Reporting FVC responses as absolute or percent changes led to similar conclusions. These results suggest adults with MetSyn exhibit enhanced hypoxic vasodilation at rest. However, hypoxic responses during exercise in obese adults and adults with MetSyn were not statistically different when compared with lean adults. Individual hypoxic vasodilatory responses were variable, suggesting diversity in vascular control.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Kinesiology, School of Education, University of Wisconsin, 1149 Natatorium, Madison, WI 53706, USA.
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Limberg JK, Harrell JW, Zillner CM, Danielson JM, Sebranek JM, Proctor LT, Schrage WG. Exercise Hyperemia and Acute Ascorbic Acid Infusion in Obesity and Metabolic Syndrome. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1108.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Limberg JK, Eldridge MW, Proctor LT, Sebranek JJ, Schrage WG. Alpha-adrenergic control of blood flow during exercise: effect of sex and menstrual phase. J Appl Physiol (1985) 2010; 109:1360-8. [PMID: 20724565 DOI: 10.1152/japplphysiol.00518.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sex differences exist in autonomic control of the cardiovascular system. This study was designed to directly test sex or female menstrual phase-related differences in α-adrenergic control of blood flow during exercise. We hypothesized that women would exhibit reduced α-adrenergic vasoconstriction compared with men during exercise; in addition, women would constrict less during the early luteal than the early follicular phase of the female menses. Young men (n = 10) were studied once and women (n = 9) studied twice, once during the early follicular phase and once during the early luteal phase of female menses. We measured forearm blood flow (FBF; Doppler ultrasound of the brachial artery) during rest and steady-state dynamic exercise (15 and 30% of maximal voluntary contraction, 20 contractions/min). A brachial artery catheter was inserted for the local administration of α-adrenergic agonists [phenylephrine (PE; α(1)) or clonidine (CL; α(2))]. Blood flow responses to exercise [forearm vascular conductance (FVC)] were similar between all groups. At rest, infusion of PE or CL decreased FVC in all groups (40-60% reduction). Vasoconstriction to PE was abolished in all groups at 15 and 30% exercise intensity. Vasoconstriction to CL was reduced at 15% and abolished at 30% intensity in all groups; women had less CL-induced constriction during the early luteal than early follicular phase (P < 0.017, 15% intensity). These results indicate that vasodilator responses to forearm exercise are comparable between men and women and are achieved through similar paths of α-adrenergic vascular control at moderate intensities; this control may differ at low intensities specific to the female menstrual phase.
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Affiliation(s)
- Jacqueline K Limberg
- Department of Kinesiology, School of Education, University of Wisconsin, Madison, WI 53706, USA
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