Liu B, Wohlfart B, Johansson B W
Department of Pharmacology, University of Lund, Sweden.
Cryobiology. 1990 Oct;27(5):539-46. doi: 10.1016/0011-2240(90)90041-2.
During hibernation the body temperature may fall to only a few degrees above 0 degree C. The heart of the hedgehog continues to function whereas the hearts of nonhibernating mammals stop beating. The present study was performed to investigate and compare the mechanical responses to hypothermia in rabbits, rats, and hedgehogs. Isometric force was recorded from papillary muscles mounted in an organ bath and effects of hypothermia on the mechanical restitution curve were also compared. A reduction of bath temperature from 35 degrees C caused an increase in peak developed force. Maximum force was seen at 20 degrees C in the rabbit, 15 degrees C in the rat, and 10 degrees C in the hedgehog preparations. In all the species there was a similar prolongation of time to peak force and of time from peak to half-relaxation as temperature was lowered. An increase in resting force and after-contractions were recorded in the rabbit and rat muscles at temperatures below 15 and 10 degrees C, respectively. The rabbit and rat preparations became inexcitable at temperatures below 10 and 5 degrees C, respectively. The hedgehog papillary muscle, on the other hand, still contracted at 0 degree C and did not show increased resting force nor after-contractions. The results are consistent with the hypothesis that there is a calcium overload in cardiac cells from rabbit and rat at low temperatures but there is no calcium overload in the hedgehog muscle during hypothermia.
在冬眠期间，体温可能会降至仅比0摄氏度高几度。刺猬的心脏仍在继续运作，而非冬眠哺乳动物的心脏则停止跳动。本研究旨在调查和比较兔子、大鼠和刺猬对低温的力学反应。从安装在器官浴中的乳头肌记录等长力，并比较低温对力学恢复曲线的影响。将浴温从35摄氏度降低会导致最大收缩力增加。在兔子中，20摄氏度时可见最大力；在大鼠中，15摄氏度时可见最大力；在刺猬标本中，10摄氏度时可见最大力。在所有物种中，随着温度降低，达到峰值力的时间以及从峰值到半松弛的时间都有类似的延长。分别在低于15摄氏度和10摄氏度时，在兔子和大鼠的肌肉中记录到静息力增加和后收缩。兔子和大鼠的标本分别在低于10摄氏度和5摄氏度时变得无法兴奋。另一方面，刺猬的乳头肌在0摄氏度时仍能收缩，且未显示静息力增加和后收缩。这些结果与以下假设一致，即低温时兔子和大鼠心脏细胞存在钙超载，而刺猬肌肉在低温期间不存在钙超载。
