Evaporative water loss from rats in the heat

Fr, Hainsworth

doi:10.1152/ajplegacy.1968.214.5.979

Cited by 69 publications

(45 citation statements)

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“…rapid rise of body temperature permitting radiation and convection of heat from the animal to the environment. Secondly, when the body temperature is above 39"C, they produce a large flow of saliva that they spread on their fur to increase evaporative loss (Hainsworth, 1968;Berg et al, 1990;Yanase et al, 1991). The submaxillary glands, which are very rich in tissue kallikrein (Orstavik, 1978), are the main effector organs of this thermolytic salivation (Hainsworth & Stricker, 1969;1972).…”

Section: Introductionmentioning

confidence: 99%

Thermolytic salivation, substance P and kinins in rats

Damas

1995

Archives of Physiology and Biochemistry

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In the heat, rats produce a large flow of saliva that they spread on their fur. We have tested whether substance P (SP) is involved in this response by using RP 67580, a NK1 tachykinin receptor antagonist, in normal and in kininogen-deficient rats. In anaesthetized rats, the sialogogic effect of SP (1 and 5 micrograms.kg-1 iv) was inhibited by RP 67580 (50 to 2500 micrograms.kg-1 iv). SP (5 micrograms.kg-1 iv) did not modify the vascular permeability to 125I-labelled albumin in submaxillary glands but increased this permeability in periglandular soft tissues and in the ears. This effect was suppressed by RP 67580 (50 to 2500 micrograms.kg-1 ip). Unanaesthetized normal male Wistar rats were exposed to ambient temperatures of 26 degrees C (thermoneutral range) or 36 degrees C for one hour. After this time period, a loss of body weight was observed. The thermolytic water loss reached 2% of body weight. This body weight loss was reduced by atropine (3 mg.kg-1 ip) or RP 67580 (50 to 2500 micrograms.kg-1 ip). The submaxillary glands were swollen and accumulated labelled albumin. This accumulation was reduced by atropine but was not affected by RP 67580. An extravasation of labelled albumin occurred in periglandular tissues. This accumulation was not modified by atropine which induced a large oedema of the soft tissues. Protein extravasation was suppressed by RP 67580 (2500 micrograms.kg-1) which did not modify or increased the volume of the oedema.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Introductionmentioning

confidence: 99%

Thermolytic salivation, substance P and kinins in rats

Damas

1995

Archives of Physiology and Biochemistry

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“…Outside this range, metabolic rate is elevated at the lower limit by enhanced heat production and at the upper limit by increased motor activity due to escape behaviour and thermoregulatory grooming (saliva spreading). However, this definition was considered unsuitable for the purposes of the proposed study, since within the temperature range defined (28-330C), body temperature is elevated above normal [Hainsworth, 1967; Hellstrom, 1975], the tail vessels are markedly dilated [Rand, Burton and Ing, 1965] and saliva spreading has been reported [Hainsworth, 1967[Hainsworth, , 1968; these effects would obviously distort the thermoregulatory responses to the amines. Clearly, a rat attempting to maintain a normal body temperature by increasing evaporative (saliva spreading) and non-evaporative (a sustained tail vasodilatation) heat loss is not in a 'neutral' condition [Mount, 1974].…”

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Body Temperature Regulation and Thermoneutrality in Rats

Poole¹,

Stephenson²

1977

Exp Physiol

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Various concepts of thermoneutrality were considered for a proposed study of the role of hypothalamic amines in temperature regulation of rats. The classic definition, the ambient temperature over which metabolic rate is minimum and constant, gave a range of approximately 28 to 32'C. However, within this temperature range rats were inactive, the inactivity apparently representing a behavioural response to heat stress and itself responsible for the reduced metabolic rate; certain thermoregulatory effectors were also activated to increase heat loss. Therefore an alternative range, 180O± 1-9 (mean ± S.D.) to 28-1 ± 1 0°C, was defined in which rats displayed normal activity, behavioural thermoregulation being absent.For a study of the thermoregulatory effects of intrahypothalamic infusions of amines in conscious unrestrained rats, knowledge of their thermoneutral range is essential. Various concepts of thermoneutrality have been advanced. The classic definition, which considers only metabolic rate, is the ambient temperature range over which metabolic rate is minimum and constant. This gives a range of 28-33°C for rats housed at 23-25°C [Herrington, 1940;Swift and Forbes, 1939]. Outside this range, metabolic rate is elevated at the lower limit by enhanced heat production and at the upper limit by increased motor activity due to escape behaviour and thermoregulatory grooming (saliva spreading). However, this definition was considered unsuitable for the purposes of the proposed study, since within the temperature range defined (28-330C), body temperature is elevated above normal [Hainsworth, 1967; Hellstrom, 1975], the tail vessels are markedly dilated [Rand, Burton and Ing, 1965] and saliva spreading has been reported [Hainsworth, 1967[Hainsworth, , 1968; these effects would obviously distort the thermoregulatory responses to the amines. Clearly, a rat attempting to maintain a normal body temperature by increasing evaporative (saliva spreading) and non-evaporative (a sustained tail vasodilatation) heat loss is not in a 'neutral' condition [Mount, 1974]. A definition which also considers behavioural thermoregulation is likely to be more appropriate, for example that of Bianca [1974]: the range of ambient temperature in which the animal neither combats cold by raising its heat production nor heat by evaporative heat loss, and in which behavioural thermoregulation is normally absent. In an attempt to delineate this range in rats, metabolic rate and activities of thermoregulatory effectors (shivering, tail vasomotor tone and behavioural thermoregulation including saliva spreading) were monitored at different ambient temperatures.143

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“…The thermoneutral zone for the albino rat has been variously reported to be 26±28°C (Clarkson et al 1972), 28±30°C (Poole and Stephenson 1977), and 28±29°C (Herrington 1940). When placed in a dierent environmental temperature or under conditions of hyperthermia, rats begin to thermoregulate by using salivation and urination to wet and cool the body; ordinarily the tail is also used as a radiator in thermoregulation (Rand et al 1965;Hainsworth 1967Hainsworth , 1968Hainsworth et al 1968). After 2 h in a dierent environmental temperature, heat dissipation is maximized.…”

Section: Discussionmentioning

confidence: 99%

Effect of environmental temperature on the interactive developmental toxicity of radiofrequency radiation and 2-methoxyethanol in rats

Nelson

Conover

Krieg

et al. 1998

International Archives of Occupational and Environmental Health

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Environmental temperature does affect the specific absorption rate (SAR) necessary to maintain a specific colonic temperature but does not affect the interactive developmental toxicity of RF radiation and 2ME in rats. These results, consistent with the literature, add to the evidence that the developmental toxicity of RF radiation (combined or alone) is associated with colonic temperature, not with SAR.

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Evaporative water loss from rats in the heat

Cited by 69 publications

References 0 publications

Thermolytic salivation, substance P and kinins in rats

Thermolytic salivation, substance P and kinins in rats

Body Temperature Regulation and Thermoneutrality in Rats

Effect of environmental temperature on the interactive developmental toxicity of radiofrequency radiation and 2-methoxyethanol in rats

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