Physiological significance of behavioral hypothermia in hypoxic toads (Bufo marinus).
Physiological significance of behavioral hypothermia in hypoxic toads (Bufo marinus).
复制标题
DOI：
--
复制
发表时间：
1991-09
期刊：
影响因子：
--
通讯作者：
S. C. Wood;G. Malvin
中科院分区：
文献类型：
--
作者：
S. C. Wood;G. Malvin
我们测试了低氧蟾蜍（Bufo marinus）在温度梯度下会选择低于正常温度的假设，这种行为反应是有益的。在常温条件下，选择体温为24.2 +/- 3.6℃，当吸入氧气为10%或更低时，平均选择温度降至15.3 +/- 2.4℃。我们测试的低氧诱导低体温的理论优势包括：(1)通过Q10效应降低摄氧量（VO2）；(2)动脉饱和度（SaO2）升高，(3)通气反应降低，(4)应激反应降低。在25℃（正常首选温度）和15℃（缺氧首选温度）下，测量呼吸常压或低氧气体混合物的蟾蜍的气体交换、红细胞压积、血红蛋白、SaO2、PaO2和pH。与25℃相比，在15℃的分级缺氧中，SaO2显著增加，VO2显著降低。25℃的分级缺氧对VO2没有显著影响，尽管有证据表明在该温度下通气增加（pH和呼吸交换比，RE增加）。在15℃时，只有吸入氧气为4%时，分级缺氧才对VO2有显著影响。25℃时，红细胞压比和血红蛋白在缺氧时显著升高，但在15℃时没有变化。暴露于10% O2（引起行为性低温的值）的蟾蜍在25℃时表现出明显的呼吸性碱中毒，而在15℃时则没有。缺氧导致SaO2和PO2在25℃时显著下降。在缺氧期间冷却至15℃，SaO2显著升高，但PaO2没有变化。综上所述，行为性低温是海蟾对缺氧的有益反应。
We tested the hypotheses that hypoxic toads (Bufo marinus) in a thermal gradient would select a lower than normal temperature and that this behavioral response would be beneficial. Under normoxic conditions, selected body temperature was 24.2 +/- 3.6 degrees C. When inspired O2 was 10% or less, mean selected temperature decreased to 15.3 +/- 2.4 degrees C. The theoretical advantages of hypoxia-induced hypothermia we tested include (1) a reduction of oxygen uptake (VO2) by a Q10 effect; (2) increased arterial saturation (SaO2), (3) a decreased ventilatory response, and (4) a decreased stress response. Gas exchange, hematocrit, hemoglobin, SaO2, PaO2 and pH were measured at 25 degrees C (normal preferred temperature) and 15 degrees C (hypoxia preferred temperature) in toads breathing normoxic or hypoxic gas mixtures. During graded hypoxia at 15 degrees C, SaO2 was significantly increased and VO2 was significantly reduced compared with 25 degrees C. Graded hypoxia did not significantly affect VO2 at 25 degrees C, despite evidence for increased ventilation at that temperature (increased pH and respiratory exchange ratio, RE). At 15 degrees C, graded hypoxia had a significant effect on VO2 only at an inspired O2 of 4%. Increased RE with hypoxia was significant at 25 degrees C but not at 15 degrees C. Hematocrit and [hemoglobin] rose significantly during graded hypoxia at 25 degrees C but did not change at 15 degrees C. Toads exposed to 10% O2 (the value that elicits behavioral hypothermia) showed a significant respiratory alkalosis at 25 degrees C but not at 15 degrees C. Likewise, hypoxia caused a significant drop in SaO2 and PO2 at 25 degrees C. Cooling to 15 degrees C during hypoxia caused a significant rise in SaO2 but no change in PaO2. In conclusion, behavioral hypothermia is a beneficial response to hypoxia in Bufo marinus.