Barney C C, West D R
Department of Biology, Hope College, Holland, MI 49423.
Physiol Behav. 1990 Sep;48(3):387-95. doi: 10.1016/0031-9384(90)90333-y.
Male rats were thermally dehydrated by exposure without water to an environmental temperature of 40 degrees C for 0-4 hr or to environmental temperatures of 25-40 degrees C for 4 hr. Water intake was then measured for 2 hr or a blood sample was taken to determine the effect of heat exposure on body water status. Evaporative water loss and water intake increased with increased duration and severity of heat exposure. Heat exposure significantly increased plasma osmolality and plasma sodium concentration and significantly decreased plasma potassium concentration. Hematocrit and plasma protein concentration increased slightly but not significantly with heat exposure. The increases in water intake in association with increases in evaporative water loss, plasma osmolality and plasma sodium concentration with no significant increases in hematocrit or plasma protein concentration indicates that the thirst induced by thermal dehydration is primarily osmotic in nature. Water intake equal to about 50% of the evaporative plus urinary water loss reduced plasma osmolality and sodium concentration to control levels, removing the stimulus to drink before the water loss was replaced.
将雄性大鼠置于无水环境中，在40℃下暴露0 - 4小时，或在25 - 40℃环境温度下暴露4小时，使其受热脱水。然后测量2小时的饮水量，或采集血样以确定热暴露对机体水状态的影响。随着热暴露时间的延长和程度的加重，蒸发失水量和饮水量增加。热暴露显著增加血浆渗透压和血浆钠浓度，并显著降低血浆钾浓度。热暴露使血细胞比容和血浆蛋白浓度略有增加，但不显著。饮水量的增加与蒸发失水量、血浆渗透压和血浆钠浓度的增加相关，而血细胞比容或血浆蛋白浓度无显著增加，这表明热脱水诱导的口渴主要是渗透性的。饮水量约为蒸发失水与尿失水量之和的50%时，可使血浆渗透压和钠浓度降至对照水平，在失水量得到补充之前消除饮水刺激。
