Clark D J, Fewell J E
Department of Medical Physiology, University of Calgary, AB, Canada.
Can J Physiol Pharmacol. 1996 Mar;74(3):331-6.
In newborn mammals, hypoxemia produces a decrease in body-core temperature (Tbc), the mechanism of which is unknown. Experiments were therefore carried out to determine whether this decrease results from a regulated or a forced thermoregulatory response. Seven Hartley strain guinea pigs were studied on postnatal days 2, 5, 10, 15, and 26 following implantation of a biotelemetry transmitter into the peritoneal cavity on day 1 to measure Tbc. During each experiment, Tbc and selected ambient temperature were determined in a thermocline (15-40 degrees C gradient) during a control period of normoxemia, an experimental period of hypoxemia (produced by decreasing the fraction of inspired oxygen from 0.21 to 0.10), and a recovery period of normoxemia. We reasoned that no change or a decrease in selected ambient temperature while Tbc decreased during hypoxemia would indicate a regulated thermoregulatory response, whereas an increase in selected ambient temperature while Tbc decreased during hypoxemia would indicate a forced thermoregulatory response. Tbc decreased during hypoxemia at all ages; the response was accentuated on days 15 and 26 compared with day 2. Selected ambient temperature decreased during hypoxemia in the youngest animals but remained the same in the older animals. Our data provide evidence that postnatal maturation influences the thermoregulatory response to hypoxemia in guinea pigs and support the hypothesis that the decrease in Tbc during hypoxemia results from a regulated thermoregulatory response.
在新生哺乳动物中，低氧血症会导致体核温度（Tbc）下降，但其机制尚不清楚。因此，开展了实验以确定这种下降是由调节性体温调节反应还是强制性体温调节反应引起的。在出生后第1天将生物遥测发射器植入腹腔，以测量7只哈特利品系豚鼠在出生后第2、5、10、15和26天的Tbc。在每个实验中，在常氧血症对照期、低氧血症实验期（通过将吸入氧分数从0.21降至0.10产生）和常氧血症恢复期，在温度梯度范围（15 - 40摄氏度）内测定Tbc和选定的环境温度。我们推断，在低氧血症期间Tbc下降时选定环境温度无变化或下降，将表明是调节性体温调节反应，而在低氧血症期间Tbc下降时选定环境温度升高，则表明是强制性体温调节反应。在所有年龄段，低氧血症期间Tbc均下降；与第2天相比，第15天和第26天的反应更为明显。在最年幼的动物中，低氧血症期间选定环境温度下降，但在年长动物中保持不变。我们的数据提供了证据，表明出生后的成熟会影响豚鼠对低氧血症的体温调节反应，并支持低氧血症期间Tbc下降是由调节性体温调节反应引起的这一假说。
