Regulation mode of evaporative cooling underlying a strategy of the heat-tolerant FOK rat for enduring ambient heat
| Autor: | Takanori Oiwa, Fujiya Furuyama, Daisuke Miyazawa, Hitoo Nishino, Yoshiaki Isobe, Etsuro Tanaka, Masataka Murakami, Hideki Hida |
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| Rok vydání: | 2003 |
| Předmět: |
Hyperthermia
Male medicine.medical_specialty Saliva Hot Temperature Physiology Submandibular Gland Saliva secretion Core temperature Biology In Vitro Techniques Heat Stress Disorders Rats Sprague-Dawley Species Specificity Physiology (medical) Internal medicine medicine Animals Strain (chemistry) Behavior Animal Strain difference medicine.disease Adaptation Physiological Rats Rats Inbred ACI Heat tolerance Endocrinology Immunology Salivation Evaporative cooler Body Temperature Regulation |
| Zdroj: | American journal of physiology. Regulatory, integrative and comparative physiology. 285(6) |
| ISSN: | 0363-6119 |
| Popis: | Compared with other rat strains, the inbred FOK rat is extremely heat tolerant. This increased heat tolerance is due largely to the animal's enhanced saliva spreading abilities. The aims of the present study were to 1) quantify the heat tolerance capacity of FOK rats and 2) determine the regulatory mode of the enhanced salivary cooling in these animals. Various strains of rats were acutely exposed to heat. In the heat-intolerant strains, saliva spreading was insufficient and the core temperature (Tc) rose rapidly. In contrast, FOK rats maintained an elevated Tcplateau (39.5 ± 0.7°C) for 5-6 h over a wide range of ambient temperatures (Ta) (37.5-42.5°C). In hot environments the FOK rats secreted copious amounts of saliva and spread it over more than the entire ventral body surface. FOK rats had a low Tcthreshold for salivation, and the salivation rate increased linearly in proportion to the Tcdeviation from the threshold. No strain difference or temperature effect was observed in the saliva secretion rate from in vitro submandibular glands perfused by sufficient doses of ACh. These results suggest that 1) the ability of FOK rats to maintain a moderate steady-state hyperthermia (39.5 ± 0.7°C) over a wide Tarange is enabled by a lowered threshold Tcfor salivation and functional negative-feedback control of saliva secretion and 2) strain differences in ability to endure heat stress are mainly attributable to changes in the thermoregulatory control system rather than altered secretory abilities of the salivary glands. |
| Databáze: | OpenAIRE |
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