Response of veins draining the nose to alar-fold temperature changes in the dog.

Magilton, J. H.; Swift, Curran S.

doi:10.1152/jappl.1969.27.1.18

Cited by 37 publications

(10 citation statements)

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“…Blood in the angularis oculi flows into the cavernous sinus and exchanges heat with arterial blood in the carotid rete, while nasal blood in the facial vein flows directly to the heart via the external jugular vein and the proportion of nasal venous blood which flows into the angularis oculi or the facial depends upon the relative resistances of the two pathways (Johnsen & Folkow, 1988). Anatomical and pharmacological studies in dogs (Magilton & Swift, 1969), rabbits (Pegram, Bevan & Bevan, 1976), sheep (Khamas & Ghoshal, 1982), reindeer (Johnsen et al 1987) and camels (Elkhawad, Al-Zaid & Bou-Resli, 1990) have demonstrated a muscular segment of the buccal facial vein which has been called a 'sphincter' by some investigators. Both the angularis oculi and the facial veins are innervated by sympathetic nerve fibres.…”

Section: Effect Of Venous Occlusion On Sbcmentioning

confidence: 99%

Selective brain cooling in goats: effects of exercise and dehydration.

Baker

Nijland

1993

The Journal of Physiology

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SUMMARY1. Measurements of brain and central blood temperature (Tbr and Tbl), metabolic rate (MR) and respiratory evaporative heat loss (REHL) were made in trained goats walking on a treadmill at 4'8 km h-' at treadmill inclines of 0, 5, 10, 15 and 20 % when they were fully hydrated and at 0 % when they had been deprived of water for 72 h.2. In hydrated goats, exercise MR increased progressively with increasing treadmill incline. Both Tbl and Tbr rose during exercise, but Tbl always rose more than Tbr, and selective brain cooling (SBC = Tbl-Tbr) increased linearly with Tbl. Significant linear relationships were also present between REHL and Tbl and between SBC and REHL. Neither the slope of the regression relating SBC to Tbl nor the threshold Tbl for onset of SBC was affected by exercise intensity. Manual occlusion of the angularis oculi veins decreased SBC in a walking goat, while occlusion of the facial veins increased SBC. 3. Dehydrated goats had higher levels of Tbl, Tbr and SBC during exercise, but the relationship between SBC and Tbl was the same in hydrated and dehydrated animals. In dehydrated animals, REHL at a given Tbl was lower and SBC was thus maintained at reduced rates of REHL.4. It is concluded that SBC is a linear function of body core temperature in exercising goats and REHL appears to be a major factor underlying SBC in exercise. The maintenance of SBC in spite of reduced REHL in dehydrated animals could be a consequence of increased vascular resistance in the facial vein and increased flow of cool nasal venous blood into the cranial cavity.

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Section: Effect Of Venous Occlusion On Sbcmentioning

confidence: 99%

Selective brain cooling in goats: effects of exercise and dehydration.

Baker

Nijland

1993

The Journal of Physiology

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“…Selective brain cooling has been observed in mammals, birds and reptiles (Caputa, 1980;Baker, 1982). Artiodactyls, such as sheep (Baker & Hayward, 1968a), goats (Taylor, 1966), and reindeer (Johnsen, Blix & Mercer, 1986), and carnivores, such as dogs (Magilton & Swift, 1969;Baker, Chapman & Nathanson, 1974) and cats (Baker, 1972), keep brain temperature lower than deep body temperature by virtue of possessing a carotid rete, which allows carotid arterial blood flowing to the brain to be cooled by venous blood draining the moist surface of the nasal mucosa (Baker, 1983). The ophthalmic rete fulfils a similar role in birds (Kilgore, 1976;Kilgore, Boggs & Birchard, 1979).…”

Section: Introductionmentioning

confidence: 99%

Effects of tracheostomy breathing on brain and body temperatures in hyperthermic sheep.

Laburn

Mitchell

et al. 1988

The Journal of Physiology

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SUMMARY1. We measured rectal and hypothalamic temperature in sheep breathing nasally and via a tracheostomy, during hyperthermia resulting from exposure to a hot environment, exercise and fever.2. In normothermic and hyperthermic sheep hypothalamic temperaturc was up to 1-0°C lower than rectal temperature when the sheep breathed nasally. Tracheostomy breathing abolished the rectal-hypothalamic temperature difference.3. In sheep breathing via the tracheostomy and exposed to a dry-bulb temperature of 45-50°C for 2 h, hypothalamic temperature exceeded rectal temperature by about 0 4°C, and was significantly higher than that in sheep breathing nasally in the same environment.4. During exercise on a treadmill and in the post-exercise period, the difference between hypothalamic and rectal temperature was abolished in the sheep while breathing through the tracheostomy, and rectal temperature rose to higher levels compared to those evident in the same activity while breathing nasally.5. After an i.v. injection of 0-4,ug/kg lipopolysaccharide (LPS), the difference between hypothalamic and rectal temperature again was abolished in the sheep when breathing through the tracheostomy, but rectal temperature rose significantly less compared to when breathing nasally.6. Our results indicate that selective brain cooling depends on upper respiratory tract cooling in normo-and hyperthermic states in sheep.

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“…When the external temperature is high, blood flows from the face toward the brain. Furthermore, changes in temperature in the region of the angular, ocular, and facial veins of the dog can be interpreted as suggesting the presence of a system that proportions blood flow between superficial and deep venous structures (11). Humans and dogs also lack a carotid rete (7).…”

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confidence: 99%

Temperature Sensitivity of Tone in the Rabbit Facial Vein: Myogenic Mechanism for Cranial Thermoregulation?

Winquist

Bevan

1980

Science

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Intrinsic myogenic tone in the buccal segment of the rabbit facial vein is exquisitely sensitive to small changes in temperature in the range 33 degrees to 44 degrees C. This particular venous segment also exhibits a preponderance of beta-adrenergic receptors and receives a dense, medial sympathetic innervation. This area of the vein is proposed to act as a temperature-sensitive sphincter that distributes cooled nasal venous blood between superficial and deep venous drainage systems in the head and neck. Deviation of cool blood to deeper venous sinuses has been shown to be an important thermoregulatory mechanism.

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Response of veins draining the nose to alar-fold temperature changes in the dog.

Cited by 37 publications

References 0 publications

Selective brain cooling in goats: effects of exercise and dehydration.

Selective brain cooling in goats: effects of exercise and dehydration.

Effects of tracheostomy breathing on brain and body temperatures in hyperthermic sheep.

Temperature Sensitivity of Tone in the Rabbit Facial Vein: Myogenic Mechanism for Cranial Thermoregulation?

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