Effects of acclimation on oxygen consumption ( QO 2) of the brain and its different areas in two genera of anurans

Abstract

1. 1. A series of experiments concerning the effects of acclimatization on the QO 2 of the brain and its different areas were performed in two species of anurans with quite different habitats and behaviour. 2. 2. Measurements of brain QO 2 at 30°C showed for acclimatization at 2–4°C and 37 ± 0·5°C a decrease in brain QO 2 of Bufo arenarum Hensel, while no significant differences were found for Leptodactylus ocellatus. In spite of the extreme acclimatization temperature the phenomenon proved to be reversible after several days at room temperature. 3. 3. Brain QO 2 measured at acclimatization temperatures showed for B. arenarum Hensel a decrease at 4°C and no differences at 20–25°C and 37 ± 0·5°C, with respect to non-acclimatized animals. 4. 4. Considering the QO 2 of the separate areas, the mesencephalon gave the highest O 2 uptake when compared with the telencephalon and medulla, and spinal cord. Oxygen uptake of the divided brain is lower than that of the intact system. The mean value obtained under these conditions was significantly lower than that found when processing the brain as a whole. 5. 5. These results suggest that L. ocellatus has a greater capacity for regulating its QO 2 to different environmental temperatures to maintain an adequate energy expenditure. Also, the different metabolic behaviour of the brain tissue depending on its anatomical integrity deserves to be emphasized.