Brenda N. Wells, Gaylene M. Russell McEvoy, Hamza Shogan, Meghan E. Kiley, Graham M. Fraser
{"title":"Fixing skeletal muscle PO2 eliminates hyperinsulinemic microvascular blood flow response","authors":"Brenda N. Wells, Gaylene M. Russell McEvoy, Hamza Shogan, Meghan E. Kiley, Graham M. Fraser","doi":"10.1111/micc.12805","DOIUrl":null,"url":null,"abstract":"<div>\n \n \n <section>\n \n <h3> Objective</h3>\n \n <p>To determine if insulin-mediated hyperemia is partially dependent on local muscle oxygen concentration.</p>\n </section>\n \n <section>\n \n <h3> Methods</h3>\n \n <p>Sprague–Dawley rats were anesthetized, and the extensor digitorum longus (EDL) was reflected onto an inverted microscope. Intravital video microscopy sequences were recorded during baseline and hyperinsulinemic euglycemia. The muscle was reflected over a glass stage insert (Experiment 1a and 1b), or over a gas exchange chamber (Experiment 2), and microvascular capillary blood flow was recorded during sequential changes (7%–12%–2%–7%) of oxygen (O<sub>2</sub>) concentration. Blood flow was measured by the red blood cell supply rate (SR) in number of cells per second. All animal protocols were approved by Memorial University's Institutional Animal Care Committee.</p>\n </section>\n \n <section>\n \n <h3> Results</h3>\n \n <p>In Experiment 1a, SR increased from 8.0 to 14.0 cells/s at baseline to euglycemia (<i>p</i> = .01), while no significant SR variation was detected after performing a sham hyperinsulinemic euglycemic clamp (Experiment 1b). In Experiment 2, SR decreased at 12% O<sub>2</sub> and increased at 2% O<sub>2</sub>, compared to 7% O<sub>2</sub>, under both experimental conditions. Magnitude of SR responses to oxygen oscillations during euglycemia were not different to those at baseline at each O<sub>2</sub> concentration (<i>p</i> > .9).</p>\n </section>\n \n <section>\n \n <h3> Conclusions</h3>\n \n <p>Our results suggest that increased blood flow observed in response to insulin is eliminated if tissue oxygen microenvironment is fixed at a given oxygen concentration.</p>\n </section>\n </div>","PeriodicalId":18459,"journal":{"name":"Microcirculation","volume":"30 4","pages":""},"PeriodicalIF":1.9000,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Microcirculation","FirstCategoryId":"3","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/micc.12805","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"HEMATOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Objective
To determine if insulin-mediated hyperemia is partially dependent on local muscle oxygen concentration.
Methods
Sprague–Dawley rats were anesthetized, and the extensor digitorum longus (EDL) was reflected onto an inverted microscope. Intravital video microscopy sequences were recorded during baseline and hyperinsulinemic euglycemia. The muscle was reflected over a glass stage insert (Experiment 1a and 1b), or over a gas exchange chamber (Experiment 2), and microvascular capillary blood flow was recorded during sequential changes (7%–12%–2%–7%) of oxygen (O2) concentration. Blood flow was measured by the red blood cell supply rate (SR) in number of cells per second. All animal protocols were approved by Memorial University's Institutional Animal Care Committee.
Results
In Experiment 1a, SR increased from 8.0 to 14.0 cells/s at baseline to euglycemia (p = .01), while no significant SR variation was detected after performing a sham hyperinsulinemic euglycemic clamp (Experiment 1b). In Experiment 2, SR decreased at 12% O2 and increased at 2% O2, compared to 7% O2, under both experimental conditions. Magnitude of SR responses to oxygen oscillations during euglycemia were not different to those at baseline at each O2 concentration (p > .9).
Conclusions
Our results suggest that increased blood flow observed in response to insulin is eliminated if tissue oxygen microenvironment is fixed at a given oxygen concentration.
期刊介绍：
The journal features original contributions that are the result of investigations contributing significant new information relating to the vascular and lymphatic microcirculation addressed at the intact animal, organ, cellular, or molecular level. Papers describe applications of the methods of physiology, biophysics, bioengineering, genetics, cell biology, biochemistry, and molecular biology to problems in microcirculation.
Microcirculation also publishes state-of-the-art reviews that address frontier areas or new advances in technology in the fields of microcirculatory disease and function. Specific areas of interest include: Angiogenesis, growth and remodeling; Transport and exchange of gasses and solutes; Rheology and biorheology; Endothelial cell biology and metabolism; Interactions between endothelium, smooth muscle, parenchymal cells, leukocytes and platelets; Regulation of vasomotor tone; and Microvascular structures, imaging and morphometry. Papers also describe innovations in experimental techniques and instrumentation for studying all aspects of microcirculatory structure and function.
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