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Šorli J, Lenasi H. The Effect of Acute Hyperglycaemia Induced by Oral Glucose Load on Heart Rate Variability and Skin Microvascular Reactivity in Young Adults. Life (Basel) 2023; 14:56. [PMID: 38255671 PMCID: PMC10817604 DOI: 10.3390/life14010056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/24/2024] Open
Abstract
We aimed to elucidate the effects of acute hyperglycaemia, induced by an oral glucose tolerance test (OGTT), on the autonomic nervous system (ANS) and skin microvascular reactivity at the time point of peak plasma glucose concentration (cglc) in 20 young, healthy participants. We assessed their heart rate variability (HRV) as a measure of the ANS activity and the parameters of post-occlusive reactive hyperaemia (PORH) to estimate skin microvascular reactivity as measured by laser Doppler (LD) fluxmetry. The tests were repeated 30 min after a standard OGTT (75 g glucose dissolved in 250 mL water) and, in a separate control experiment, after drinking the same amount of water. Participants had their cglc and serum insulin measured at three consecutive time-points according to the testing protocol. The low-frequency (LF) spectral power, the LF to high-frequency (LF/HF) ratio, and the diastolic blood pressure increased significantly more after water than after OGTT, and there was a trend of the peak LD flux of PORH decreasing more after OGTT than after water. Significant correlations between some PORH and all the HRV parameters and cglc increase after OGTT were found, implying diminished vascular reactivity evoked by hyperglycaemia in healthy subjects with lower glucose tolerance.
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Affiliation(s)
- Jernej Šorli
- General Hospital Dr. Franc Derganc, 5290 Šempeter pri Gorici, Slovenia
| | - Helena Lenasi
- Institute of Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
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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 PMCID: PMC11178292 DOI: 10.1152/ajpregu.00169.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 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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Greenshields JT, Keeler JM, Freemas JA, Baker TB, Johnson BD, Carter SJ, Schlader ZJ. Cutaneous microvascular vasodilatory consequences of acute consumption of a caffeinated soft drink sweetened with high-fructose corn syrup. Physiol Rep 2021; 9:e15074. [PMID: 34676680 PMCID: PMC8531600 DOI: 10.14814/phy2.15074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 09/09/2021] [Accepted: 09/19/2021] [Indexed: 11/24/2022] Open
Abstract
This study tested the hypotheses that compared to drinking water, consumption of a caffeinated soft drink sweetened with high-fructose corn syrup (HFCS) attenuates the cutaneous vasodilatory response to local skin heating without (Protocol 1) and following ischemia-reperfusion injury (Protocol 2). In a randomized, counterbalanced crossover design, 14 healthy adults (25 ± 3 year, 6 women) consumed 500 ml of water (water) or a caffeinated soft drink sweetened with HFCS (Mtn. Dew, DEW). Thirty minutes following beverage consumption local skin heating commenced on the right forearm (Protocol 1), while on the left forearm ischemia-reperfusion commenced with 20 min of ischemia followed by 20 min of reperfusion and then local skin heating (Protocol 2). Local skin heating involved 40 min of heating to 39℃ followed by 20 min of heating to 44℃. Skin blood flow (SkBf, laser Doppler) data were normalized to mean arterial pressure and are presented as a cutaneous vascular conductance (CVC) and as percentage of the CVC response during heating to 44℃ (%CVCmax ). Protocol 1: During local heating at 39℃, no differences were observed in CVC (water: 2.0 ± 0.6 PU/mmHg; DEW: 2.0 ± 0.8 PU/mmHg, p = 0.83) or %CVCmax (water: 59 ± 14%; DEW 60 ± 15%, p = 0.84) between trials. Protocol 2: During local skin heating at 39℃, no differences were observed in CVC (water: 1.7 ± 0.5 PU/mmHg; DEW: 1.5 ± 0.5 PU/mmHg, p = 0.33) or %CVCmax (water: 64 ± 15%; DEW 61 ± 15% p = 0.62) between trials. The cutaneous microvascular vasodilator response to local heating with or without prior ischemia-reperfusion injury is not affected by acute consumption of a caffeinated soft drink sweetened with HFCS.
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Affiliation(s)
- Joel T. Greenshields
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
| | - Jason M. Keeler
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
| | - Jessica A. Freemas
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
| | - Tyler B. Baker
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
| | - Blair D. Johnson
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
| | - Stephen J. Carter
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
- Cancer Prevention and Control ProgramIndiana University Melvin and Bren Simon Comprehensive Cancer CenterIndianapolisIndianaUSA
| | - Zachary J. Schlader
- H.H. Morris Human Performance LaboratoriesDepartment of KinesiologySchool of Public HealthIndiana UniversityBloomingtonIndianaUSA
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Investigation of proteins important for microcirculation using in vivo microdialysis after glucose provocation: a proteomic study. Sci Rep 2021; 11:19093. [PMID: 34580391 PMCID: PMC8476624 DOI: 10.1038/s41598-021-98672-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/13/2021] [Indexed: 11/08/2022] Open
Abstract
Insulin has metabolic and vascular effects in the human body. What mechanisms that orchestrate the effects in the microcirculation, and how the responds differ in different tissues, is however not fully understood. It is therefore of interest to search for markers in microdialysate that may be related to the microcirculation. This study aims to identify proteins related to microvascular changes in different tissue compartments after glucose provocation using in vivo microdialysis. Microdialysis was conducted in three different tissue compartments (intracutaneous, subcutaneous and intravenous) from healthy subjects. Microdialysate was collected during three time periods; recovery after catheter insertion, baseline and glucose provocation, and analyzed using proteomics. Altogether, 126 proteins were detected. Multivariate data analysis showed that the differences in protein expression levels during the three time periods, including comparison before and after glucose provocation, were most pronounced in the intracutaneous and subcutaneous compartments. Four proteins with vascular effects were identified (angiotensinogen, kininogen-1, alpha-2-HS-glycoprotein and hemoglobin subunit beta), all upregulated after glucose provocation compared to baseline in all three compartments. Glucose provocation is known to cause insulin-induced vasodilation through the nitric oxide pathway, and this study indicates that this is facilitated through the interactions of the RAS (angiotensinogen) and kallikrein-kinin (kininogen-1) systems.
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Högstedt A, Ghafouri B, Tesselaar E, Farnebo S. Sampling insulin in different tissue compartments using microdialysis: methodological aspects. Sci Rep 2020; 10:21948. [PMID: 33319790 PMCID: PMC7738523 DOI: 10.1038/s41598-020-78728-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 11/26/2020] [Indexed: 01/25/2023] Open
Abstract
Sampling the concentration of insulin in human skin using microdialysis is challenging because of low intracutaneous concentrations and low recovery, presumably due to adsorption of insulin to the microdialysis system. In this study, we aimed to (1) measure how the concentration of insulin varies in three different tissue compartments (intracutaneous, subcutaneous and intravenous) and (2) to study how much insulin is adsorbed to the microdialysis catheter membranes and tubing during a typical microdialysis experiment, both in vivo and in vitro. We hypothesized that (1) the concentration of insulin decreases from the intravenous compartment to the intracutaneous and subcutaneous tissue, and that (2) adsorption of insulin to the microdialysis membrane and tubing impairs the recovery of insulin from the tissue. In this experimental study, microdialysis catheters were inserted intracutaneously, subcutaneously and intravenously in 11 healthy subjects. Systemic endogenous hyperinsulinemia was induced by intake of an oral glucose load. Insulin concentration was measured in the dialysate and in the extracted samples from the catheter membrane and tubings. In vitro microdialysis was performed to investigate the temporal resolution of the adsorption. After an oral glucose load insulin concentration increased intravenously, but not in the intracutaneous or subcutaneous compartments, while glucose, lactate and pyruvate concentrations increased in all compartments. The adsorption of insulin to the microdialysis membrane in vivo was highest in the intravenous compartment (p = 0.01), compared to the intracutaneous and subcutaneous compartments. In vitro, the adsorption to the microdialysis membrane was highest one hour after sampling, then the concentration gradually decreased after three and five hours of sampling. The concentration of insulin in peripheral tissues is low, probably due to decreasing tissue vascularity. Adsorption of insulin to the microdialysis membrane is modest but time-dependent. This finding highlights the importance of a stabilization time for the microdialysis system before sampling tissue analytes.
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Affiliation(s)
- Alexandra Högstedt
- Department of Surgery in Linköping, and Department of Biomedical and Clinical Sciences, Faculty of Health Sciences, Linköping University, 58185, Linköping, Sweden.
| | - Bijar Ghafouri
- Pain and Rehabilitation Centre, and Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
| | - Erik Tesselaar
- Department of Medical Radiation Physics, and Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
| | - Simon Farnebo
- Department of Hand Surgery, Plastic Surgery and Burns, and Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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Reminy K, Hue O, Antoine-Jonville S. Effect of warm environment on the skin blood flow response to food intake. Int J Hyperthermia 2020; 37:836-842. [PMID: 32635784 DOI: 10.1080/02656736.2020.1788174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Warm exposure places high demands on thermoregulation mechanisms, which depend on the effectiveness of the microvascular function. The associations between the microcirculation and metabolism in warm environments have received little attention. The purpose of this study was to explore skin blood flow (SkBF) in response to food intake in a warm environment compared to control. METHODS Thirty-two healthy, acclimated-to-warm-environment and physically active participants were recruited (20 females and 12 males). They participated in two sessions (warm environment: 31 °C and control: 20 °C, presented in randomized order). SkBF was measured before and after standardized food intake through the acquisition of perfusion signals by laser Doppler flowmetry (Periflux System 5000), following a local heating protocol. RESULTS SkBF was affected by the environmental temperature, showing an increase in the warm environment compared to control (all p < .001). SkBF was significantly affected by food intake (all p < .007), being reduced after meals. In the men's group, SkBF was reduced in both environmental temperatures after meals. In women, meals affected SkBF at 20 °C but not in the warm environment. CONCLUSION These results may indicate a competition between thermo- and glyco-regulation in a warm environment to the detriment of glucose homeostasis in women.
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Affiliation(s)
- K Reminy
- Laboratoire ACTES (Adaptation Climat Tropical Exercice Santé, EA3596), Université des Antilles, Pointe-à-Pitre, Guadeloupe, France
| | - O Hue
- Laboratoire ACTES (Adaptation Climat Tropical Exercice Santé, EA3596), Université des Antilles, Pointe-à-Pitre, Guadeloupe, France
| | - S Antoine-Jonville
- Laboratoire ACTES (Adaptation Climat Tropical Exercice Santé, EA3596), Université des Antilles, Pointe-à-Pitre, Guadeloupe, France
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Stokes SM, Bertin FR, Stefanovski D, Belknap JK, Medina-Torres CE, Pollitt CC, van Eps AW. Lamellar energy metabolism and perfusion in the euglycaemic hyperinsulinaemic clamp model of equine laminitis. Equine Vet J 2020; 52:577-584. [PMID: 31845378 DOI: 10.1111/evj.13224] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/29/2019] [Accepted: 12/04/2019] [Indexed: 01/19/2023]
Abstract
BACKGROUND Hyperinsulinaemia is associated with the development of endocrinopathic laminitis; however, the mechanisms remain unclear. OBJECTIVES Evaluate the effects of hyperinsulinaemia on lamellar energy metabolism and perfusion during laminitis development. STUDY DESIGN In vivo experiment. METHODS Eight Standardbred horses were instrumented with a microdialysis probe in the lamellae of a forelimb. A 24 hours baseline period (BASELINE) was followed by 48 hours of a continuous euglycaemic hyperinsulinaemic clamp (EHC) from 24 to 72 hours (CLAMP). Microdialysate was collected every 6 hours and analysed for glucose, lactate and pyruvate concentrations and lactate-to-pyruvate ratio (L:P). Microdialysis urea clearance was used to estimate lamellar tissue perfusion. Archived microdialysis samples from six identically instrumented Standardbred horses served as controls (CON). Variables were compared over time and between EHC and CON horses using a mixed-effects linear regression model. RESULTS Glucose concentration decreased during the CLAMP period in CON and EHC horses (P < .001), but there was no difference between CON and EHC (P > .9). Lactate concentration increased during the CLAMP period in CON and EHC horses (P < .001), however, the rate of increase was significantly higher in EHC horses relative to CON (P = .014). There was a relative increase in pyruvate concentration in EHC horses compared with CON during the CLAMP period (P = .03). L:P increased significantly in CON horses during the CLAMP period (P < .001) but not in EHC (P = .1). Urea clearance did not change in CON (P = .9) or EHC (P = .05) during the CLAMP, but did increase in EHC relative to CON (P = .02). MAIN LIMITATIONS The effects of microdialysis probe implantation on perfusion and metabolism remain unclear. The EHC model may not mimic natural endocrinopathic laminitis. CONCLUSIONS Laminitis developed without evidence of lamellar hypoperfusion or energy stress. Therapies to improve perfusion are unlikely to affect the initial development of endocrinopathic laminitis.
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Affiliation(s)
- Simon M Stokes
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Francois R Bertin
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Darko Stefanovski
- New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania
| | - James K Belknap
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio
| | - Carlos E Medina-Torres
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Christopher C Pollitt
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Andrew W van Eps
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia.,New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania
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Högstedt A, Iredahl F, Tesselaar E, Farnebo S. Effect of N G -monomethyl l-arginine on microvascular blood flow and glucose metabolism after an oral glucose load. Microcirculation 2019; 27:e12597. [PMID: 31628700 DOI: 10.1111/micc.12597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 09/09/2019] [Accepted: 10/16/2019] [Indexed: 12/28/2022]
Abstract
OBJECTIVE The aim of this study was to investigate whether the effects on local blood flow and metabolic changes observed in the skin after an endogenous systemic increase in insulin are mediated by the endothelial nitric oxide pathway, by administering the nitric oxide synthase inhibitor NG -monomethyl l-arginine using microdialysis. METHODS Microdialysis catheters, perfused with NG -monomethyl l-arginine and with a control solution, were inserted intracutaneously in 12 human subjects, who received an oral glucose load to induce a systemic hyperinsulinemia. During microdialysis, the local blood flow was measured by urea clearance and by laser speckle contrast imaging, and glucose metabolites were measured. RESULTS After oral glucose intake, microvascular blood flow and glucose metabolism were both significantly suppressed in the NG -monomethyl l-arginine catheter compared to the control catheter (urea clearance: P < .006, glucose dialysate concentration: P < .035). No significant effect of NG -monomethyl l-arginine on microvascular blood flow was observed with laser speckle contrast imaging (P = .81). CONCLUSION Local delivery of NG -monomethyl l-arginine to the skin by microdialysis reduces microvascular blood flow and glucose delivery in the skin after oral glucose intake, presumably by decreasing local insulin-mediated vasodilation.
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Affiliation(s)
- Alexandra Högstedt
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Fredrik Iredahl
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Erik Tesselaar
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.,Department of Medical Radiation Physics, Linköping University, Linköping, Sweden
| | - Simon Farnebo
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.,Department of Hand Surgery, Plastic Surgery and Burns, Linköping University, Linköping, Sweden
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Horová E, Pelcl T, Šoupal J, Škrha J, Flekač M, Vejražka M, Škrha J, Prázný M. Postprandial microvascular reactivity is significantly modified by endogenous insulin in recently diagnosed Type 2 diabetic patients. Diabetes Res Clin Pract 2018. [PMID: 29518486 DOI: 10.1016/j.diabres.2018.02.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Eva Horová
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Tomáš Pelcl
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Jan Šoupal
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Jan Škrha
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Milan Flekač
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Martin Vejražka
- Institute of Medical Biochemistry and Laboratory Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Jan Škrha
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Martin Prázný
- 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.
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Response of Blood Perfusion at ST 36 Acupoint after Drinking Cold Glucose or Saline Injection. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017; 2017:4212534. [PMID: 28465703 PMCID: PMC5390596 DOI: 10.1155/2017/4212534] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/05/2017] [Indexed: 12/16/2022]
Abstract
Skin blood flux (SkBF) changes caused by drinking cold water are generally associated with vagal tone and osmotic factors in digestive system. According to acupuncture theory, change of SkBF at ST 36 might reflect the functional changes of digestive system. The aim of this study is to analyze the changes of SkBF after drinking 3°C 0.9% saline or 5% glucose injection by monitor blood flux at bilateral ST 36. The results indicated that, after drinking different cold water, the change ratio of SkBF at right side ST 36 has been different. Because all solutions have the same temperature (3°C) and both saline and glucose solution have the same osmolality, suggesting that the SkBF changes resulting from drinking cold water are not regulated just by the vagal tone and osmolality, there must have been other factors. These results have not been consistent with the frequency domain results of heart rate variability (HRV) analysis. Coherence analysis of blood flux signals at bilateral ST 36 indicated that there have been different coherence-frequency curves among different groups in special frequency bands, which suggested that coherence analysis might provide a potential tool to evaluate different status.
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Methodological concerns with laser speckle contrast imaging in clinical evaluation of microcirculation. PLoS One 2017; 12:e0174703. [PMID: 28358906 PMCID: PMC5373607 DOI: 10.1371/journal.pone.0174703] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 03/13/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Laser Speckle Contrast Imaging (LSCI) is a non-invasive and fast technique for measuring microvascular blood flow that recently has found clinical use for burn assessment and evaluation of flaps. Tissue motion caused by for example breathing or patient movements may however affect the measurements in these clinical applications, as may distance between the camera and the skin and tissue curvature. Therefore, the aims of this study were to investigate the effect of frame rate, number of frames/image, movement of the tissue, measuring distance and tissue curvature on the measured perfusion. METHODS Methyl nicotinate-induced vasodilation in the forearm skin was measured using LSCI during controlled motion at different speeds, using different combinations of frame rate and number of frames/image, and at varying camera angles and distances. Experiments were made on healthy volunteers and on a cloth soaked in a colloidal suspension of polystyrene microspheres. RESULTS Measured perfusion increased with tissue motion speed. The relation was independent of the absolute perfusion in the skin and of frame rate and number of frames/image. The measured perfusion decreased with increasing angles (16% at 60°, p = 0.01). Measured perfusion did not vary significantly between measurement distances from 15 to 40 cm (p = 0.77, %CV 0.9%). CONCLUSION Tissue motion increases and measurement angles beyond 45° decrease the measured perfusion in LSCI. These findings have to be taken into account when LSCI is used to assess moving or curved tissue surfaces, which is common in clinical applications.
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