Role of adenosine in the hypoxia-induced hypothermia of toads

Luiz G. S. Branco, Alexandre A. Steiner, Glenn J. Tattersall, Stephen C. Wood
2000 American Journal of Physiology. Regulatory Integrative and Comparative Physiology  
of adenosine in the hypoxia-induced hypothermia of toads. Am J Physiol Regulatory Integrative Comp Physiol 279: R196-R201, 2000. -The concept that hypoxia elicits a drop in body temperature (T b ) in a wide variety of animals is not new, but the mechanisms remain unclear. We tested the hypothesis that adenosine mediates hypoxia-induced hypothermia in toads. Measurements of selected T b were performed using a thermal gradient. Animals were injected (into the lymph sac or
more » ... ) with aminophylline (an adenosine receptor antagonist) followed by an 11-h period of hypoxia (7% O 2 ) or normoxia exposure. Control animals received saline injections. Hypoxia elicited a drop in T b from 24.8 Ϯ 0.3 to 19.5 Ϯ 1.1°C (P Ͻ 0.05). Systemically applied aminophylline (25 mg/kg) did not change T b during normoxia, indicating that adenosine does not alter normal thermoregulatory function. However, aminophylline (25 mg/kg) significantly blunted hypoxia-induced hypothermia (P Ͻ 0.05). To assess the role of central thermoregulatory mechanisms, a smaller dose of aminophylline (0.25 mg/kg), which did not alter hypoxia-induced hypothermia systemically, was injected into the fourth cerebral ventricle. Intracerebroventricular injection of aminophylline (0.25 mg/kg) caused no significant change in T b under normoxia, but it abolished hypoxia-induced hypothermia. The present data indicate that adenosine is a central and possibly peripheral mediator of hypoxia-induced hypothermia. thermoregulation; aminophylline; body temperature; behavior; anapyrexia
doi:10.1152/ajpregu.2000.279.1.r196 pmid:10896882 fatcat:xqzi4ouovzb25kuhizkfxpqwbu