The effect of the head or neck cooling on body core temperature and thermal sensation in humans (1104.6)

Redistribution of blood from the viscera to the peripheral vasculature is the major cardiovascular response designed to restore thermoregulatory homeostasis after an elevation in body core temperature. In this study, we investigated the role of the hypothalamic paraventricular nucleus (PVN) in the reflex decrease in renal blood flow that is induced by hyperthermia, as this brain region is known to play a key role in renal function and may contribute to the central pathways underlying thermoregulatory responses. In anesthetized rats, blood pressure, heart rate, renal blood flow, and tail skin temperature were recorded in response to elevating body core temperature. In the control group, saline was microinjected bilaterally into the PVN; in the second group, muscimol (1 nmol in 100 nl per side) was microinjected to inhibit neuronal activity in the PVN; and in a third group, muscimol was microinjected outside the PVN. Compared with control, microinjection of muscimol into the PVN did not significantly affect the blood pressure or heart rate responses. However, the normal reflex reduction in renal blood flow observed in response to hyperthermia in the control group (∼70% from a resting level of 11.5 ml/min) was abolished by the microinjection of muscimol into the PVN (maximum reduction of 8% from a resting of 9.1 ml/min). This effect was specific to the PVN since microinjection of muscimol outside the PVN did not prevent the normal renal blood flow response. The data suggest that the PVN plays an essential role in the reflex decrease in renal blood flow elicited by hyperthermia.

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MK801 impairs thermoregulation in the heat

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y02-055 ◽

2002 ◽

Vol 80 (3) ◽

pp. 226-232 ◽

Cited By ~ 5

Author(s):

Frédéric Canini ◽

Nadine Simler ◽

Lionel Bourdon

Keyword(s):

Locomotor Activity ◽

Nmda Receptor ◽

Receptor Antagonist ◽

Core Temperature ◽

Exposure Duration ◽

Heat Exposure ◽

Nmda Receptor Antagonist ◽

Dopamine Metabolism ◽

Body Core Temperature ◽

Body Core

The effects of MK801 (dizocilpine), a glutamate NMDA receptor antagonist, on thermoregulation in the heat were studied in awake rats exposed to 40°C ambient temperature until their body core temperature reached 43°C. Under these conditions, MK801-treated rats exhibited enhanced locomotor activity and a steady rise in body core temperature, which reduced the heat exposure duration required to reach 43°C. Since MK801-treated rats also showed increased striatal dopaminergic metabolism at thermoneutrality, the role of dopamine in the MK801-induced impairment of thermoregulation in the heat was determined using co-treatment with SCH23390, a dopamine D1 receptor antagonist. SCH23390 normalized the locomotor activity in the heat without any effect on the heat exposure duration. These results suggest that the MK801-induced impairment of thermoregulation in the heat is related to neither a dopamine metabolism alteration nor a locomotor activity enhancement.Key words: heatstroke, NMDA receptor, thermoregulation, dopamine, locomotion.

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Body Fatness, Body Core Temperature, and Heat Loss During Moderate-Intensity Exercise

Aviation Space and Environmental Medicine ◽

10.3357/asem.3627.2013 ◽

2013 ◽

Vol 84 (11) ◽

pp. 1153-1158 ◽

Cited By ~ 15

Author(s):

Jayme D. Limbaugh ◽

Gregory S. Wimer ◽

Lynn H. Long ◽

William H. Baird

Keyword(s):

Heat Loss ◽

Core Temperature ◽

Body Core Temperature ◽

Moderate Intensity ◽

Moderate Intensity Exercise ◽

Body Fatness ◽

Body Core

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Measuring body core temperature using a novel non-invasive sensor

Extreme Physiology & Medicine ◽

10.1186/2046-7648-4-s1-a28 ◽

2015 ◽

Vol 4 (S1) ◽

Cited By ~ 1

Author(s):

Yoram Epstein ◽

Savyon Mazgaoker ◽

Doron Gruber ◽

Daniel S Moran ◽

Ran Yanovich ◽

...

Keyword(s):

Core Temperature ◽

Body Core Temperature ◽

Non Invasive ◽

Body Core

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Responses of Motor-Sport Athletes to V8 Supercar Racing in Hot Conditions

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2.2.182 ◽

2007 ◽

Vol 2 (2) ◽

pp. 182-191 ◽

Cited By ~ 16

Author(s):

Matt B. Brearley ◽

James P. Finn

Keyword(s):

Perceived Exertion ◽

Thermal Sensation ◽

Sweat Rate ◽

Thermal Strain ◽

Body Core Temperature ◽

Hydration Status ◽

Borg Scale ◽

Thermal Discomfort ◽

Body Core ◽

Cardiovascular Strain

Background:Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.Purpose:To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.Methods:Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.Results:Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.Conclusions:Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.

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