Effect of face immersion on body temperature and tail blood flow in the rat

1971 ◽  
Vol 40 (3) ◽  
pp. 659-668 ◽  
Author(s):  
B.A. Gooden
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Face Immersion ◽  
Tail Blood

Body temperature control of rat tail blood flow

1983 ◽  
Vol 245 (3) ◽  
pp. R426-R432 ◽  
Author(s):  
E. R. Raman ◽  
M. F. Roberts ◽  
V. J. Vanhuyse
Keyword(s):  
Blood Flow ◽  
Heat Exchange ◽  
Body Temperature ◽  
Heat Flow ◽  
Thermal Conductance ◽  
Venous Occlusion ◽  
Albino Rats ◽  
Blood Flows ◽  
Rat Tail ◽  
Tail Blood

Tail blood flow (BF) and heat flow (HF) were measured in five albino rats during transients in rectal temperature (Tre) caused by body heating at rest. During heating, tail temperature (Tt) was kept at 15, 20, 25, 30, 35, or 42 degrees C by enclosing the tail in a water-perfused tube. Thermal conductance (K) was computed as HF/(Tre-Tt). BF was measured by venous occlusion plethysmography. Heating caused a rise in Tre that was accompanied by proportional increases in both K and BF. The ratio R = K/BF represents conductance per unit BF and reflects the amount of heat exchange for a given BF. R can thus be used to estimate the distribution of BF within the tail. R was independent of Tre at all Tt, indicating that BF distribution is controlled by the tail. R was low at low Tt and rose at higher Tt. This suggests that at low Tt, blood flows primarily in central veins of the tail and at higher Tt blood flows in peripheral tail veins.

TEMPERATURE REGULATION IN EXERCISE

PEDIATRICS ◽  
1963 ◽  
Vol 32 (4) ◽  
pp. 691-702
Author(s):  
Sid Robinson
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Heat Stroke ◽  
The Body ◽  
Physiological Regulation ◽  
Temperature Changes ◽  
Metabolic Heat ◽  
Warm Blood ◽  
Hot Environments ◽  
Large Increments

The central body temperature of a man rises gradually during the first half hour of a period of work to a higher level and this level is precisely maintained until the work is stopped; body temperature then slowly declines to the usual resting level. During prolonged work the temperature regulatory center in the hypothalamus appears to be reset at a level which is proportional to the intensity of the work and this setting is independent of environmental temperature changes ranging from cold to moderately warm. In hot environments the resistance to heat loss may be so great that all of the increased metabolic heat of work cannot be dissipated and the man's central temperature will rise above the thermostatic setting. If this condition of imbalance is continued long enough heat stroke will ensue. We have found that in a 3 mile race lasting only 14 minutes on a hot summer day a runner's rectal temperature may rise to 41.1°C., with heat stroke imminent. The physiological regulation of body temperature of men in warm environments and during the increased metabolic heat production of work is dependent on sweating to provide evaporative cooling of the skin, and on adjustments of cutaneous blood flow which determine the conductance of heat from the deeper tissues to the skin. The mechanisms of regulating these responses during work are complex and not entirely understood. Recent experiments carried out in this laboratory indicate that during work, sweating may be regulated by reflexes originating from thermal receptors in the veins draining warm blood from the muscles, summated with reflexes from the cutaneous thermal receptors, both acting through the hypothalamic center, the activity of which is increased in proportion to its own temperature. At the beginning of work the demand for blood flow to the muscles results in reflex vasoconstriction in the skin. As the body temperature rises the thermal demand predominates and the cutaneous vessels dilate, increasing heat conductance to the skin. Large increments in cardiac output and compensatory vasoconstriction in the abdominal viscera make these vascular adjustments in work possible without circulatory embarrassment.

Effect of two methods of hand heating on body temperature, forearm blood flow, and deep venous oxygen saturation

1990 ◽  
Vol 259 (5) ◽  
pp. E639-E643 ◽  
Author(s):  
I. W. Gallen ◽  
I. A. Macdonald
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Oxygen Content ◽  
Forearm Blood Flow ◽  
Venous Blood ◽  
Blood Oxygen ◽  
Left Hand ◽  
Venous Oxygen Saturation ◽  
Baseline Values ◽  
Healthy Females

Two methods of hand heating [warmed blanket 40 degrees C (WB) and warm-air box 55 degrees C (WA)] were compared with the effect of no heating (control) in six healthy females. After 30 min baseline, the left hand was either heated for 1 h or not heated. Measurements were made of skin temperature (ST), core temperature (CT), right forearm (FBF) and skin blood flow (SBF), and right forearm deep venous blood oxygen content with and without occlusion of the hand circulation. CT rose above baseline in WB (by +0.2 degrees C, P less than 0.01) but not with control or WA. Abdominal ST rose only with WB (by +0.66 degrees C above baseline, P less than 0.01). FBF increased above baseline values with both WA (by +10 ml.l forearm-1.min-1) and WB (by +12 ml.l forearm-1.min-1), but neither was significantly greater than the control. SBF increased above baseline only with WB (by +202 mV, P less than 0.01), and this was significantly greater than control SBF. With an occluded hand circulation, deep venous oxygen content rose above baseline values with WB only (+6.0%, P less than 0.01) but was not greater than control with either method of hand heating. We conclude that using a warm-air box has less effect than a heated blanket on the measured variables.

scholarly journals Body temperature influences regional tissue blood flow during retrograde cerebral perfusion

1997 ◽  
Vol 114 (3) ◽  
pp. 440-447 ◽  
Author(s):  
Akihiko Usui ◽  
Keiji Oohara ◽  
Fumihiko Murakami ◽  
Hideki Ooshima ◽  
Mitsuo Kawamura ◽  
...  
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Cerebral Perfusion ◽  
Tissue Blood Flow ◽  
Retrograde Cerebral Perfusion

Heat acclimation and hypohydration: involvement of central angiotensin II receptors in thermoregulation

1999 ◽  
Vol 277 (1) ◽  
pp. R47-R55 ◽  
Author(s):  
Michal Horowitz ◽  
Pavel Kaspler ◽  
Eckhart Simon ◽  
Ruediger Gerstberger
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Angiotensin Ii ◽  
Heat Acclimation ◽  
Angiotensin Ii Receptors ◽  
Ang Ii ◽  
Biphasic Response ◽  
Temperature Thresholds ◽  
Before And After ◽  
Tail Blood

This investigation attempted to confirm the involvement of central ANG II-ergic signals in thermoregulation. Experiments were conducted on rats undergoing short (STHA)- and long (LTHA)-term heat acclimation, with and without superimposed hypohydration. Vasodilatation (VTsh) and salivation (STsh) temperature thresholds, tail blood flow, and heat endurance were measured in conscious rats during heat stress (40°C) before and after losartan (Los), an ANG II AT1-selective receptor antagonist, administration either to the lateral ventricle or intravenously. Heat acclimation alone resulted in decreased VTsh. STsh decreased during STHA and resumed the preacclimation value, together with markedly increased heat endurance on LTHA. Hypohydration did not affect this biphasic response, although STsh was elevated in all groups. The enhanced heat endurance attained by LTHA was blunted. Neither Los treatment affected the nonacclimated rats. In the heat-acclimated, euhydrated rats, intracerebroventricular Los resulted in decreased VTsh, whereas intravenous Los resulted in elevated STsh. Both intracerebroventricular and intravenous Los led to markedly enhanced heat endurance of the LTHA hypohydrated rats. It is concluded that the LTHA group showed a loss of the benefits acquired by acclimation on hypohydration, whereas the STHA rats, which show an accelerated autonomic excitability in that phase, gained some benefit. It is suggested that ANG II modulates thermoregulation in conditions of chronic adjustments. Central ANG II signals may lead to VTsh upshift, whereas circumventricular structures, activated via circulating ANG II, decrease STsh. On hypohydration these responses seem to be desensitized.

Effects of immersion of the hand in cold water on digital blood flow

1965 ◽  
Vol 20 (1) ◽  
pp. 61-64 ◽  
Author(s):  
A. C. L. Hsieh ◽  
T. Nagasaka ◽  
L. D. Carlson
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Cold Water ◽  
Regression Equation ◽  
Finger Blood Flow ◽  
Circulatory Response ◽  
Cold Induced Vasodilatation ◽  
Digital Blood Flow

The temperatures of the tip of the middle fingers ( Ts) of nine comfortably warm subjects have been recorded during immersion of all the fingers of one hand in a 27–liter bath containing slowly stirred water at temperatures ranging from 4.6 to 40 C ( Tw). Blood flow ( F = ml/cm2 per min) was estimated from the average Ts for the last 15 min of a 20-min period, Tw and body temperature ( Tb) by using the equation: F = 1,087 x K( Ts – Tw)/ ( Tb – Ts). (K = 0.0134 kcal/cm2 per min per °C.) The increase in F per °C reduction in Tw below 10 C was 0.16 ± 0.077 (P < .05). This value gives a measure of the vasodilatation occasioned by immersion in water below 10 C. The sample regression equation of F on Tw was: F = 4.1 – .16 Tw ± 0.17 (n = 27; range of Tw = 4.6 to 10 C). This method of estimating blood flow at several levels of Tw describes more fully the peripheral circulatory response to cold than methods in which only one level of Tw is used. cold-induced vasodilatation; temperature and finger blood flow Submitted on August 28, 1963

Circadian rhythm in sweating and cutaneous blood flow

1984 ◽  
Vol 246 (3) ◽  
pp. R321-R324 ◽  
Author(s):  
L. A. Stephenson ◽  
C. B. Wenger ◽  
B. H. O'Donovan ◽  
E. R. Nadel
Keyword(s):  
Blood Flow ◽  
Circadian Rhythm ◽  
Body Temperature ◽  
Forearm Blood Flow ◽  
Sweat Rate ◽  
Circadian Variation ◽  
Esophageal Temperature ◽  
Cutaneous Blood Flow ◽  
Cutaneous Vasodilation ◽  
Cutaneous Blood

To characterize the changes in the control of the heat loss responses associated with the circadian variation in body temperature, we studied five men during 20 min of exercise in 25 degrees C on 6 separate days. Experiments were conducted at six times, equally spaced over the 24-h day. Esophageal temperature (Tes) and chest sweat rate (msw) were measured continuously, and forearm blood flow (FBF) was measured one to two times per minute. The thresholds for sweating and forearm vasodilation were significantly higher at 1600 and 2000 than at 2400 and 0400, averaging 0.57 and 0.65 degrees C higher, respectively, at 1600 than at 0400. Resting Tes and the Tes thresholds for cutaneous vasodilation and sweating during exercise all showed a similar circadian rhythm. The level at which core temperature is regulated therefore varies over the 24-h day with the zenith occurring around 1600 and the nadir at 0400. However, whereas the slope of the msw-to-Tes relation did not change over the 24-h day, the slope of the FBF-to-Tes relation tended to increase between 0400 and 2400, implying that the circadian rhythm may be more complex than just a shift in the central reference temperature.

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