scholarly journals Independent and combined impact of hypoxia and acute inorganic nitrate ingestion on thermoregulatory responses to the cold

2021 ◽  
Vol 121 (4) ◽  
pp. 1207-1218
Author(s):  
Josh T. Arnold ◽  
Stephen J. Bailey ◽  
Simon G. Hodder ◽  
Naoto Fujii ◽  
Alex B. Lloyd
Keyword(s):  
Blood Flow ◽  
Cooling Rate ◽  
Skin Blood Flow ◽  
Rectal Temperature ◽  
Onset Time ◽  
Rate Of Change ◽  
Vascular Control ◽  
Delta Change ◽  
Core Cooling ◽  
The Impact

Abstract Purpose This study assessed the impact of normobaric hypoxia and acute nitrate ingestion on shivering thermogenesis, cutaneous vascular control, and thermometrics in response to cold stress. Method Eleven male volunteers underwent passive cooling at 10 °C air temperature across four conditions: (1) normoxia with placebo ingestion, (2) hypoxia (0.130 FiO2) with placebo ingestion, (3) normoxia with 13 mmol nitrate ingestion, and (4) hypoxia with nitrate ingestion. Physiological metrics were assessed as a rate of change over 45 min to determine heat loss, and at the point of shivering onset to determine the thermogenic thermoeffector threshold. Result Independently, hypoxia expedited shivering onset time (p = 0.05) due to a faster cooling rate as opposed to a change in central thermoeffector thresholds. Specifically, compared to normoxia, hypoxia increased skin blood flow (p = 0.02), leading to an increased core-cooling rate (p = 0.04) and delta change in rectal temperature (p = 0.03) over 45 min, yet the same rectal temperature at shivering onset (p = 0.9). Independently, nitrate ingestion delayed shivering onset time (p = 0.01), mediated by a change in central thermoeffector thresholds, independent of changes in peripheral heat exchange. Specifically, compared to placebo ingestion, no difference was observed in skin blood flow (p = 0.5), core-cooling rate (p = 0.5), or delta change in rectal temperature (p = 0.7) over 45 min, while nitrate reduced rectal temperature at shivering onset (p = 0.04). No interaction was observed between hypoxia and nitrate ingestion. Conclusion These data improve our understanding of how hypoxia and nitric oxide modulate cold thermoregulation.

Effect of continuous negative-pressure breathing on skin blood flow during exercise in a hot environment

1998 ◽  
Vol 84 (6) ◽  
pp. 1845-1851 ◽  
Author(s):  
Kei Nagashima ◽  
Hiroshi Nose ◽  
Akira Takamata ◽  
Taketoshi Morimoto
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Negative Pressure ◽  
Venous Occlusion ◽  
Peak Oxygen Consumption ◽  
Hot Environment ◽  
Significant Difference ◽  
Negative Pressure Breathing ◽  
The Impact ◽  
Cardiopulmonary Baroreceptors

To assess the impact of continuous negative-pressure breathing (CNPB) on the regulation of skin blood flow, we measured forearm blood flow (FBF) by venous-occlusion plethysmography and laser-Doppler flow (LDF) at the anterior chest during exercise in a hot environment (ambient temperature = 30°C, relative humidity = ∼30%). Seven male subjects exercised in the upright position at an intensity of 60% peak oxygen consumption rate for 40 min with and without CNPB after 20 min of exercise. The esophageal temperature (Tes) in both conditions increased to 38.1°C by the end of exercise, without any significant differences between the two trials. Mean arterial pressure (MAP) increased by ∼15 mmHg by 8 min of exercise, without any significant difference between the two trials before CNPB. However, CNPB reduced MAP by ∼10 mmHg after 24 min of exercise ( P < 0.05). The increase in FBF and LDF in the control condition leveled off after 18 min of exercise above a Tes of 37.7°C, whereas in the CNPB trial the increase continued, with a rise in Tes despite the decrease in MAP. These results suggest that CNPB enhances vasodilation of skin above a Tes of ∼38°C by stretching intrathoracic baroreceptors such as cardiopulmonary baroreceptors.

scholarly journals Skin blood flow measurements during heat stress: technical and analytical considerations

2020 ◽  
Vol 318 (1) ◽  
pp. R57-R69 ◽  
Author(s):  
Georgia K. Chaseling ◽  
Craig G. Crandall ◽  
Daniel Gagnon
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Skin Blood Flow ◽  
Research Question ◽  
The Body ◽  
Control Mechanisms ◽  
Vascular Control ◽  
Subsequent Increase ◽  
Flow Measurements ◽  
Doppler Flowmetry

During heat stress, the skin vasculature can greatly increase conductance secondary to vasodilation. The subsequent increase in skin blood flow allows for convective heat transfer from the core to the skin and between the skin surface and the surrounding environment. Measurement of skin blood flow, therefore, provides valuable information regarding heat exchange between the body and the environment. In addition, assessment of skin blood flow can be used to study vascular control mechanisms. Most often, skin blood flow is measured by venous occlusion plethysmography, Doppler ultrasound, laser-Doppler flowmetry, and, more recently, optical coherence tomography. However, important delimitations to each of these methods, which may be dependent on the research question, must be considered when responses from these approaches are interpreted. In this brief review, we discuss these methods of skin blood flow measurement and highlight potential sources of error and limitations. We also provide recommendations to guide the interpretation of skin blood flow data.

scholarly journals Hypoxic cutaneous vasodilation is sustained during brief cold stress and is not affected by changes in CO2

2010 ◽  
Vol 108 (4) ◽  
pp. 788-792 ◽  
Author(s):  
Grant H. Simmons ◽  
Sarah M. Fieger ◽  
Christopher T. Minson ◽  
John R. Halliwill
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Cold Stress ◽  
Skin Blood Flow ◽  
Cold Exposure ◽  
Whole Body ◽  
Cutaneous Vasodilation ◽  
Hypercapnic Hypoxia ◽  
Hypoxic Vasodilation ◽  
The Impact

Hypoxia decreases core body temperature in animals and humans during cold exposure. In addition, hypoxia increases skin blood flow in thermoneutral conditions, but the impact of hypoxic vasodilation on vasoconstriction during cold exposure is unknown. In this study, skin blood flow was assessed using laser-Doppler flowmetry, and cutaneous vascular conductance (CVC) was calculated as red blood cell flux/mean arterial pressure and normalized to baseline ( n = 7). Subjects were exposed to four different conditions in the steady state (normoxia and poikilocapnic, isocapnic, and hypercapnic hypoxia) and were cooled for 10 min using a water-perfused suit in each condition. CVC increased during all three hypoxic exposures (all P < 0.05 vs. baseline), and the magnitude of these steady-state responses was not affected by changes in end-tidal CO2 levels. During poikilocapnic and hypercapnic hypoxia, cold exposure reduced CVC to the same levels observed during normoxic cooling ( P > 0.05 vs. normoxia), whereas CVC remained elevated throughout cold exposure during isocapnic hypoxia ( P < 0.05 vs. normoxia). The magnitude of vasoconstriction during cold stress was similar in all conditions ( P > 0.05). Thus the magnitude of cutaneous vasodilation during steady-state hypoxia is not affected by CO2 responses. In addition, the magnitude of reflex vasoconstriction is not altered by hypoxia, such that the upward shift in skin blood flow (hypoxic vasodilation) is maintained during whole body cooling.

scholarly journals The improvement of the functional condition of micro-vascular endothelium among the aged people with metabolic syndrome under quercetin influence

2020 ◽  
pp. 65-71
Author(s):  
Oleg . Korkushko ◽  
Olena Bondarenko ◽  
Georgij Duzhak ◽  
Ivanna Antonuk-Shchehlova ◽  
Svitlana Naskalova ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Metabolic Syndrome ◽  
Blood Flow ◽  
Functional State ◽  
Skin Blood Flow ◽  
Recovery Period ◽  
Control Group ◽  
Doppler Flowmetry ◽  
Vasomotor Function ◽  
The Impact

Abstract. The Aim of study is the impact of course application of quercetin on the functional state of the endothelium of the microvessels in elderly people with metabolic syndrome. Materials and methods. We examined 110 patients (55 primary and 55 control patients) with metabolic syndrome (MS). Patients in the main group (n = 55) received quercetin ("Kvertin", chewing tablets manufactured by PJSC "Borshchagovsky KFZ", 80 mg 3 times a day) during 3 months. The control group patients (n = 55) received placebo tablets. The volume velocity of skin blood flow in the region of the middle third of the inner surface of the forearm was determined using the laser doppler flowmetry (LDP) on the apparatus BLF-21D (Transonic Systems Inc, USA). The functional state of the endothelium of microvessels was examined in a sample with post-exclusive hyperemia by clamping shoulder vessels of with a cuff for 3 minutes, in which the pressure exceeded the systolic blood pressure of the subject by 50 mm Hg. Blood pressure was measured by the Erkameter 3000 (Germany) mercury sphygmomanometer on the shoulder artery in accordance with ESH recommendations. Results. In the group of patients receiving quercetin, when performing a test with post-occlusive hyperemia, there was a statistically significant increase in the maximum volumetric velocity of the skin blood flow and the duration of the recovery period, the volumetric velocity of the skin blood flow to the initial level, which indicates an improvement in the vasomotor function of the microvessel endothelium. Improvement of the functional state of the endothelium occurred in 38 of 55 patients (69%) examined and was accompanied by a significant decrease in the level of systolic and diastolic blood pressure. Patients in the control group showed no improvement in the indices of vasomotor function of the microvessel endothelium. Conclusions. Course application of quercetin improves the functional state of the endothelium of microvessels, which helps to lower blood pressure in patients with metabolic syndrome. Key words: metabolic; syndrome; quercetin; functional state of the endothelium; arterial pressure

Influence of female reproductive hormones on local thermal control of skin blood flow

1999 ◽  
Vol 87 (5) ◽  
pp. 1719-1723 ◽  
Author(s):  
Nisha Charkoudian ◽  
Dan P. Stephens ◽  
Kenna C. Pirkle ◽  
Wojciech A. Kosiba ◽  
John M. Johnson
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Thermal Control ◽  
Reproductive Hormones ◽  
Whole Body ◽  
Vascular Control ◽  
Local Cooling ◽  
Doppler Flowmetry ◽  
Vasodilator Response ◽  
Local Warming

Progesterone and estrogen modify thermoregulatory control such that, when both steroids are elevated, body temperature increases and the reflex thermoregulatory control of cutaneous vasodilation is shifted to higher internal temperatures. We hypothesized that the influence of these hormones would also include effects on local thermal control of skin blood flow. Experiments were conducted in women in high-hormone (HH) and low-hormone (LH) phases of oral contraceptive use. Skin blood flow was measured by laser-Doppler flowmetry, and local temperature (Tloc) was controlled over 12 cm2 around the sites of blood flow measurement. Tloc was held at 32°C for 10–15 min and was then decreased at one site from 32 to 20°C in a ramp over 20 min. Next, Tloc was increased from 32 to 42°C in a ramp over 15 min at a separate site. Finally, Tloc at both sites was held at 42°C for 30 min to elicit maximum vasodilation; data for cutaneous vascular conductance (CVC) are expressed relative to that maximum. Whole body skin temperature (Tsk) was held at 34°C throughout each study to minimize reflex effects from differences in Tsk between experiments. Baseline CVC did not differ between phases [8.18 ± 1.38 (LH) vs. 8.41 ± 1.31% of maximum (HH); P > 0.05]. The vasodilator response to local warming was augmented in HH ( P < 0.05, ANOVA). For example, at Tloc of 40–42°C, CVC averaged 76.41 ± 3.08% of maximum in HH and 67.71 ± 4.43% of maximum in LH ( P < 0.01 LH vs. HH). The vasoconstrictor response to local cooling was unaffected by phase ( P > 0.05). These findings indicate that modifications in cutaneous vascular control by female steroid hormones include enhancement of the vasodilator response to local warming and are consistent with reports of the influence of estrogen to enhance nitric oxide-dependent vasodilator responses.

scholarly journals Effects of lycium and lycium-composed formula on the peripheral coldness induced by local cooling in mice

2016 ◽  
Vol 8 (3) ◽  
pp. 353
Author(s):  
Jian-Rong Zhou ◽  
Bunka Ishikawa ◽  
Mihoko Nakashima ◽  
Kazumi Yokomizo
Keyword(s):  
Blood Flow ◽  
Surface Temperature ◽  
Skin Blood Flow ◽  
Rectal Temperature ◽  
Skin Surface ◽  
Whole Body ◽  
Skin Surface Temperature ◽  
Local Cooling ◽  
Recovery Rates ◽  
Respective Control

<p>Recently people appealing for peripheral coldness increase. Lycium fruits have a long tradition of use in nutrition and traditional medicine in East Asia, while its effect on peripheral coldness is not yet investigated. We study the effects of lycium and lycium-rich formula (Ligustrum lucidum ait, LLA) on the peripheral coldness induced by local cooling in mice.</p><p>7-week old male ddY mice were administered either water (control) or lycium or LLA for 2 weeks. After an aesthesia, the mouse body except for head was immersed into 10 ℃ water for 10 min. Then the skin surface and rectal temperature of mouse were measured with a thermocamera and a thermocouple thermometer, respectively. And two laser Doppler flow probes were set to measure the skin blood flow of plantar and tail, respectively.</p><p>In the case of 1-week administration on mice, 10% lycium- and 10% LLA-treatments showed good recovery of whole body surface temperature measured by a thermocamera. After 2-week administration on mice, there were not significant differences in the recovery rates of rectal temperature compared with those of the control group. And the 30 min- and 50 min-recovery rates of dorsal skin surface temperature by 1% and 10% lycium-treatment were significantly higher than those of the respective control. Further, the 30 min- and 50 min-plantar skin blood flow by 10% LLA-treatment were significantly higher than those of the respective control. The 50 min-tail skin blood flow by 10% LLA-treatment and 60 min-tail skin blood flow by 1% LLA-treatment were significantly higher than those of the control, respectively.</p>It can be concluded that the administration of lycium or LLA on mouse led to an increase of peripheral blood blow, and thus a recovery of skin surface temperature.

Evaluation of skin blood flow using laser speckle phenomena (V)

1986 ◽  
Vol 6 (3) ◽  
pp. 335-338
Author(s):  
Hitoshi Fujii ◽  
Toshimitsu Asakura ◽  
Yasuhiro Harada ◽  
Kunihiko Nohira ◽  
Yoshihisa Shintomi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Laser Speckle

Effekt of blood flow shutdown on the vein damage when exposed to HIFU

2017 ◽  
pp. 46-50
Author(s):  
Н.Н. Петрищев ◽  
Д.Ю. Семенов ◽  
А.Ю. Цибин ◽  
Г.Ю. Юкина ◽  
А.Е. Беркович ◽  
...  
Keyword(s):  
Blood Flow ◽  
Structural Changes ◽  
Focused Ultrasound ◽  
Vena Cava ◽  
Posterior Wall ◽  
High Intensity Focused Ultrasound ◽  
Vein Wall ◽  
Ultrasound Exposure ◽  
Isolated Segment ◽  
The Impact

The purpose. In the study we investigated the impact of the partial blood flow shutdown on structural changes in the rabbit vena cava posterior wall after exposure to high-intensity focused ultrasound (HIFU). Methods. Ultrasound Exposure: frequency of 1.65 MHz, the ultrasound intensity in the focus of 13.6 kW/cm, the area of the focal spot 1 mm, continuous ultrasound, exposure for 3 seconds. Results. Immediately after HIFU exposure all layers of the vein wall showed characteristic signs of thermal damage. A week after exposure structural changes in the intima, media and adventitia was minimal in the part of vessel with preserved blood flow, and after 4 weeks the changes were not revealed. A week after HIFU exposure partial endothelium destruction, destruction of myocytes, disorganization and consolidation of collagen fibers of the adventitia were observed in an isolated segment of the vessel, and in 4 weeks endothelium restored and signs of damage in media and adventitia persisted, but were less obvious than in a week after exposure. Conclusion. The shutdown of blood flow after exposure to HIFU promotes persistent changes in the vein wall. Vein compression appears to be necessary for the obliteration of the vessel, when using HIFU-technology.

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