Crisanti K C, Fewell J E
Department of Physiology and Biophysics, The University of Calgary Health Sciences Centre, Calgary, Alberta T2N 4N1, Canada.
J Appl Physiol (1985). 1998 Sep;85(3):1150-9. doi: 10.1152/jappl.1998.85.3.1150.
In newborns and adults of a number of species, exposure to acute hypoxemia produces a "regulated" decrease in core temperature, the mechanism of which is unknown. The present experiments were carried out in chronically instrumented newborn (5-10 days of age; n = 59) and older (25-30 days of age; n = 61) guinea pigs to test the hypothesis that the endogenous opioids mediate this regulated decrease in core temperature. During an experiment, core temperature, oxygen consumption, and selected ambient temperature were measured in a thermocline (linear temperature gradient of 10-40 degreesC) during a control period of normoxemia, an experimental period of normoxemia or hypoxemia (inspired oxygen fraction 0.10), and during a recovery period of normoxemia following an intraperitoneal injection of naloxone hydrochloride (a nonspecific opioid antagonist; 1, 2, or 4 mg/kg) or vehicle. Naloxone did not significantly alter basal core temperature or the core temperature response to acute hypoxemia in newborn or older guinea pigs. Naloxone did, however, decrease basal oxygen consumption in newborn and older guinea pigs and altered the thermoregulatory effector mechanism used to decrease core temperature during hypoxemia in the newborn guinea pigs. Our data do not support the hypothesis that the endogenous opioids mediate the regulated decrease in core temperature that occurs in newborn and older guinea pigs during exposure to acute hypoxemia.
在许多物种的新生儿和成年个体中，暴露于急性低氧血症会导致核心体温出现“调节性”下降，其机制尚不清楚。本实验在长期植入仪器的新生豚鼠（5 - 10日龄；n = 59）和较大豚鼠（25 - 30日龄；n = 61）中进行，以检验内源性阿片类物质介导这种核心体温调节性下降的假说。在实验过程中，于热梯度层（10 - 40摄氏度的线性温度梯度）中，在常氧血症的对照期、常氧血症或低氧血症（吸入氧分数0.10）的实验期以及腹腔注射盐酸纳洛酮（一种非特异性阿片类拮抗剂；1、2或4毫克/千克）或赋形剂后的常氧血症恢复期，测量核心体温、氧耗量和选定的环境温度。纳洛酮并未显著改变新生或较大豚鼠的基础核心体温或对急性低氧血症的核心体温反应。然而，纳洛酮确实降低了新生和较大豚鼠的基础氧耗量，并改变了新生豚鼠在低氧血症期间用于降低核心体温的体温调节效应机制。我们的数据不支持内源性阿片类物质介导新生和较大豚鼠在暴露于急性低氧血症期间出现的核心体温调节性下降这一假说。
