科研之友
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摘要
The thermoregulatory activity has led to an extensive search for correlations between physiological variables, including metabolic functions, and the ideal level of body temperature. Snakes were also often seen basking, when their body temperatures were relatively independent of ambient temperature, indicating successful thermoregulation. Bothrops jararaca were exposed to two different ambient temperatures (20 and 30oC) over a time course of three weeks and oxygen consumption and body temperature were measured. The snakes exhibited a freerunning rhythm of body temperature. Metabolic rate wasincreased at the same circadian phase as the increase in body temperature in the 30oC. The increase of body temperature and oxygen consumption of B. jararaca occurs in the scotophase of the photoperiod, consistent with that of nocturnal species. However, prior to a scotophase period the snakes under 20oC maintain body temperature and oxygen consumption at higher levels during the day. These results demonstrate for the first time that ectothermic animals may display physiologically generated circadian rhythms of bodytemperature similar to those recorded in endotherms. Circadian rhythms allow animals to anticipate environmental changes: physiological parameters such as body temperature andmobilization of energy reserves have to be adjusted before the expected environmental changes actually take place. A atividade termorreguladora conduziu a uma busca extensiva para o entendimento das correla es entre as vari芍veis fisiol車gicas, incluindo as fun es metab車licas e a temperatura corporal. Frequentes observa es mostram que algumas serpentes podem se aquecer, sendo este aumento de temperatura independente da temperatura ambiente, indicando a termorregula o bem sucedida. Bothrops jararaca foramexpostas a dois ambientes com diferentes temperaturas (20 e 30oC) durante tr那s semanas, sendo mensuradas a temperatura corporal e o consumo de oxig那nio. O aumento da temperatura corporal e consumo de oxig那nio de Bothrops jararaca ocorreram na fase de escuro do fotoper赤odo, consistente para esp谷cies noturnas. Entretanto, antecedendo a fase de escuro, as serpentes em 20oC apresentaram os n赤veis mais elevados durante o dia para temperatura corporal e consumo de oxig那nio. Estes resultados indicam pela primeira vezque animais termodependentes podem controlar a temperatura corporal por meio de ritmos fisiol車gicos circadianos, semelhante aos observados em termoindependentes. Os ritmos circadianos permitem que os animais antecipem as mudan as no ambiente: parametros fisiol車gicos como a tempe
