Cold Exposure of Southdown and Welsh Mountain Sheep. 2. Effects of breed, plane of nutrition and previous acclimatization to cold upon skin temperature, heart rate, shivering and respiration rate

1969 ◽  
Vol 11 (1) ◽  
pp. 77-89 ◽  
Author(s):  
A. R. Sykes ◽  
J. Slee

SUMMARYShorn Southdown and Welsh Mountain sheep on high or maintenance levels of nutrition were subjected to two acute (−20°C; 4 mph wind) cold exposures in climate chambers. Before and between exposures the sheep were kept in either a cold (+8°C) or a thermoneutral (+30°C) environment.1. At +8°C, all the sheep shivered and showed sustained vasoconstriction and elevated heart rates.2. At + 30°C, heart rates, skin temperatures on the extremities and muscular tone were all consistently higher in sheep which had previously been kept at +8°C.3. During cooling, the onset of vasoconstriction and increase in heart rate were both delayed in sheep previously kept at + 8°C.4. These effects (2, 3) were retained for at least 2 days but less than 12 days after the sheep returned to thermoneutrality. They decayed faster than the increased resistance to body cooling produced simultaneously in the same sheep (Sykes and Slee, 1969), since this was still detectable after 2 weeks.5. Breed differences were mainly small.6. It was concluded that acclimatization induced by chronic cold exposure was associated with a temporary increase in basal metabolic rate.

1968 ◽  
Vol 10 (1) ◽  
pp. 17-35 ◽  
Author(s):  
A. R. Sykes ◽  
J. Slee

Closely shorn Scottish Blackface female sheep aged 9–14 months, half on high plane and half on low plane nutrition, were subjected, in climate chambers, to two short acute cold exposures down to −20°C. The acute exposures were separated by two weeks chronic exposure to a moderately subcriticai temperature (+8°C) or to a thermoneutral temperature (+30°C). Most of the sheep showed a greater resistance to body cooling at the second acute exposure (Slee and Sykes, 1967). This increased resistance to hypothermia, defined as acclimatization, was apparently influenced more by acute than by chronic cold exposure. The present paper deals with changes in skin temperature, heart rate, shivering intensity and skinfold thickness which also resulted from cold exposure, and accompanied acclimatization.After acute cold exposure followed by chronic exposure to +8°C the following changes in these parameters were observed:1. Extremity skin temperatures and heart rates were consistently increased at thermoneutral ambient temperatures.2. Vasoconstriction of the extremities and increased heart rate, both of which normally occur during the early stages of cold exposure, were delayed.3. Heart rates at sub-zero ambient temperatures were increased.4. Cold-induced vasodilatation at sub-zero ambient temperatures was increased.After acute cold treatment alone the intensity of shivering during the second acute exposure was reduced. Also the onset of foot vasoconstriction was slightly delayed.A highly significant relationship was observed between shivering intensity and heart rate during cold exposure.Plane of nutrition had less effect on the physiological responses to cooling than did previous cold experience.It was suggested in discussion that the physiological responses associated with acclimatization were: elevated basal metabolic rate, delayed onset of vasoconstriction and delayed metabolic response to cold, and consequent lowering of the critical temperature. Summit metabolism was also increased and shivering intensity reduced during acute cold exposure. Some of these responses could have resulted from either acute or chronic moderate cold exposure. However their persistence, once induced, appeared to depend upon continued exposure to moderate cold.


Author(s):  
Nima Ahmadi ◽  
Farzan Sasangohar ◽  
Tariq Nisar ◽  
Valerie Danesh ◽  
Ethan Larsen ◽  
...  

Objective To identify physiological correlates to stress in intensive care unit nurses. Background Most research on stress correlates are done in laboratory environments; naturalistic investigation of stress remains a general gap. Method Electrodermal activity, heart rate, and skin temperatures were recorded continuously for 12-hr nursing shifts (23 participants) using a wrist-worn wearable technology (Empatica E4). Results Positive correlations included stress and heart rate (ρ = .35, p < .001), stress and skin temperature (ρ = .49, p < .05), and heart rate and skin temperatures (ρ = .54, p = .0008). Discussion The presence and direction of some correlations found in this study differ from those anticipated from prior literature, illustrating the importance of complementing laboratory research with naturalistic studies. Further work is warranted to recognize nursing activities associated with a high level of stress and the underlying reasons associated with changes in physiological responses. Application Heart rate and skin temperature may be used for real-time detection of stress, but more work is needed to validate such surrogate measures.


1965 ◽  
Vol 209 (1) ◽  
pp. 227-230 ◽  
Author(s):  
Tetsuo Nagasaka ◽  
Loren D. Carlson

Oxygen consumption, heart rate, and colonic, pinna, and paw temperatures were recorded continuously in warm-adapted (W-A) and cold-adapted (C-A) dogs anesthetized with pentobarbital sodium (30 mg/kg), paralyzed with Flaxedil (5 mg/kg per hr), and mechanically ventilated. The dogs were infused with norepinephrine (1.25 µg/kg per min) for 20 min at 30 C and after 45 min of acute cold exposure to 5 C. Oxygen consumption of C-A dogs increased with a slight increase in the heart rate during the initial 18–20 min of body cooling. O2 consumption decreased continuously during cold exposure in W-A dogs. Calorigenic effects of infused noradrenaline were similar in C-A and W-A dogs at 30 C and 5 C. Heart rate increased in W-A dogs at 30 and 5 C. These results show that nonshivering thermogenesis is well developed by cold acclimation in dogs, and suggest that the increase may be due to an increase in noradrenaline in blood rather than to increased sensitivity of the animals to the calorigenic effects of noradrenaline.


1963 ◽  
Vol 18 (3) ◽  
pp. 483-488 ◽  
Author(s):  
B. S. Kang ◽  
S. H. Song ◽  
C. S. Suh ◽  
S. K. Hong

Oral temperatures of Korean diving women (ama) were measured before and after diving work in four seasons of the year. Their basal metabolic rate, measured in four seasons, was compared to that of nondiving women who lived in the same community and ate the same diet as the ama. Average oral temperatures declined to 35 C after 70 min of work in summer (water temp., 27 C) and to 33 C after 15 min of work in the winter (water temp., 10 C). Average body temperature, computed from weighted oral and average skin temperatures, declined to 34.6 C in summer and to 30 C in winter. Duration of work periods was determined principally by water temperature, since oral temperature declined at a rate inversely proportional to water temperature. The lower deep body temperatures which the ama endure in winter do, however, prolong their winter work period. The BMR of nondiving women was the same as the Dubois standard throughout the year. However, the BMR of ama varied with the season, ranging from +5 of the Dubois standard in summer to +35 in winter. We conclude that the elevated BMR of ama during the winter is cold adaptation, induced by repeated immersion in cold water. Submitted on November 23, 1962


1962 ◽  
Vol 13 (1) ◽  
pp. 165 ◽  
Author(s):  
TE Allen

Zebu, Jersey, and Zebu x Jersey crossbred heifers were subjected to a rising temperature regime over the range 65 to 105°F. Sweating rates, respiration rates, skin temperatures, and rectal temperatures were measured. All breeds showed similar responses in skin temperature and rectal temperature to increase in air temperature. The increase in skin temperature was approximately linear with rise in air temperature. Rectal temperature did not commence to rise until an air temperature of 90°F and a skin temperature of 98° was reached. Breed differences in sweating and respiratory rates with increase in air and skin temperature were observed. The Jersey heifers showed an early and almost linear increase in sweating rate with rise in air and skin temperature, whereas the sweating rate of the Zebu heifers did not increase until air temperature had risen to at least 85°F and skin temperature to 95°. Two crossbreds began to increase their sweating rates at temperatures intermediate between those recorded for Zebus arid Jerseys. The remaining two behaved similarly to Jerseys. All three breeds showed similar maximum sweating rates in response to this rising temperature regime. The respiratory rate of' the Jerseys was higher than that of the Zebus at all temperatures, and particularly at high temperatures. Crossbreds respired at rates comparable to the Jerseys until an air temperature of 90°F and a skin temperature of 97°F were exceeded, when their respiration rates became intermediate between the other two breeds. The significance of these differences is discussed.


2000 ◽  
Vol 203 (20) ◽  
pp. 3153-3159 ◽  
Author(s):  
J.B. Williams ◽  
B.I. Tieleman

The ‘energy demand’ hypothesis for short-term adjustments in basal metabolic rate (BMR) posits that birds adjust the size of their internal organs relative to food intake, a correlate of energy demand. We tested this hypothesis on hoopoe larks (Alaemon alaudipes), inhabitants of the Arabian desert, by acclimating birds for 3 weeks at 15 degrees C and at 36 degrees C, then measuring their BMR and total evaporative water loss (TEWL). Thereafter, we determined the dry masses of their brain, heart, liver, kidney, stomach, intestine and muscles of the pectoral region. Although mean body mass did not differ initially between the two groups, after 3 weeks, birds in the 15 degrees C group had gained mass (44.1+/−6.5 g), whereas larks in the 36 degrees C group had maintained a constant mass (36.6+/−3.6 g; means +/− s.d., N=6). Birds in the 15 degrees C group had a mean BMR of 46.8+/−6.9 kJ day(−1), whereas birds in the 36 degrees C group had a BMR of 32.9+/−6.3 kJ day(−1), values that were significantly different when we controlled for differences in body mass. When measured at 35 degrees C, larks in the cold-exposure group had a TEWL of 3.55+/−0.60 g H(2)O day(−)(1), whereas TEWL for birds in the 36 degrees C group averaged 2.23+/−0.28 g H(2)O day(−1), a difference of 59.2%. Mass-independent TEWL differed significantly between groups. Larks in the 15 degrees C group had a significantly larger liver, kidney and intestine than larks in the 36 degrees C group. The total increase in organ mass contributed 14.3% towards the total mass increment in the cold exposure group. Increased food intake among larks in the cold group apparently resulted in enlargement of some of the internal organs, and the increase in mass of these organs required a higher rate of oxygen uptake to support them. As oxygen demands increased, larks apparently lost more evaporative water, but the relationship between increases in BMR and TEWL remains unresolved.


1963 ◽  
Vol 18 (6) ◽  
pp. 1209-1212 ◽  
Author(s):  
Robert J. T. Joy

Nine healthy males were infused with norepinephrine (o. μg/kg min) for 20 min before and after five 40-hr weeks of seminude exposure to 5 C. All infusions were given in the basal state, in a quiet room at 27 C, after a 30-min period of control measurements. Rectal temperatures and respiratory rates were unchanged either by the drug or the intervening cold exposure. The drug increased respiratory minute volumes and tidal volumes and decreased heart rates, but equally so in both experiments. Mean skin temperatures were unaffected by the drug but were significantly (P < .025) higher after cold exposure (mean 1 C). Both basal and drug-induced increase above basal of systolic and diastolic blood pressures was significantly lower (P < .025) after cold exposure. Oxygen consumption was the same in both basal periods and was unaffected by the drug before cold exposure. After cold exposure, norepinephrine produced a significant (P < .025) increase in oxygen consumption (mean 18 cc/min m2). These results show a changed sensitivity to norepinephrine in cold-exposed men, with a decrease in vasopressor response and the development of a calorigenic response. The data suggest that in men, norepinephrine may be a mediator of a nonshivering thermogenesis occurring with cold acclimatization. Note: (With the Assistance of Joseph C. Matone, Gerald W. Newcomb, and Wendell C. Bradford) cold exposure; catecholamines; norepinephrine calorigenesis; nonshivering thermogenesis Submitted on May 2, 1963


2011 ◽  
Vol 300 (6) ◽  
pp. H2300-H2307 ◽  
Author(s):  
Melissa A. Inglott ◽  
Melissa M. J. Farnham ◽  
Paul M. Pilowsky

The rostral ventrolateral medulla differentially regulates sympathetic output to different vascular beds, possibly through the release of various neurotransmitters and peptides that may include pituitary adenylate cyclase-activating polypeptide (PACAP). An intrathecal administration of PACAP increases splanchnic sympathetic nerve activity and heart rate, but not mean arterial blood pressure. The mechanism behind this response is unknown but may be due to a differential control of sympathetic outflows. In this study we sought 1) to investigate whether intrathecal PACAP differentially affects sympathetic outflow, 2) to determine whether the intrathecal responses to PACAP are solely due to a spinally mediated mechanism, and 3) to determine whether intrathecal PACAP affects metabolic function. Experiments using urethane-anesthetized, vagotomized, ventilated, and paralyzed adult male Sprague-Dawley rats were conducted in this study. Intrathecal injections of PACAP-38 were given, and mean arterial pressure, heart rate, the activity of regional sympathetic nerves, end-tidal CO2, and core temperature were recorded. The novel findings of this study are that 1) intrathecal PACAP-38 causes a prolonged widespread sympathoexcitation in multiple sympathetic beds, 2) this widespread sympathoexcitation is mediated within the spinal cord itself since spinal transection does not abrogate the response, and 3) that intrathecal PACAP-38 increases basal metabolic rate. Therefore, we conclude that intrathecal PACAP acts in the spinal cord to cause a prolonged widespread sympathoexcitation and that PACAP also causes an increase in basal metabolic rate that includes an increase in brown adipose tissue thermogenesis in our rat preparation.


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