Karasov W H, Han L R, Munger J C
Department of Wildlife Ecology, University of Wisconsin, Madison 53706.
Am J Physiol. 1988 Jul;255(1 Pt 2):R174-7. doi: 10.1152/ajpregu.1988.255.1.R174.
The energy expenditure of animals in their natural surroundings can be determined by measuring the turnover in body water of isotopes of oxygen and hydrogen. We evaluated the use of infrared spectrophotometry for measuring 2H2O in small (20-microliters) water samples also labeled with 18O. For 2H2O over the enrichment range of 0.1-1 atom%, there was a linear relationship between infrared absorbance and 2H2O enrichment. 2H2O enrichments could be measured with a precision and accuracy of less than or equal to 1%, using this relationship. The presence of 18O in water samples in enrichments of up to 1 atom% had no significant effect on measurement of 2H2O by infrared absorbance. We measured the simultaneous turnover rates of 2H2O and 3H in mice and turtles also labeled with 18O. Our results validated the use of infrared absorbance in doubly labeled water measures of energy expenditure and indicated that the fractionation factors in vivo for 2H2O and 3H do not differ.
动物在自然环境中的能量消耗可以通过测量氧和氢的同位素在体内水分中的周转率来确定。我们评估了红外分光光度法用于测量同样标记有(^{18}O)的小体积（(20)微升）水样中(^{2}H_{2}O)的情况。对于(^{2}H_{2}O)在(0.1 - 1)原子%的富集范围内，红外吸光度与(^{2}H_{2}O)富集度之间存在线性关系。利用这种关系，(^{2}H_{2}O)富集度的测量精度和准确度可达小于或等于(1%)。水样中(^{18}O)的富集度高达(1)原子%时，对通过红外吸光度测量(^{2}H_{2}O)没有显著影响。我们测量了同样标记有(^{18}O)的小鼠和海龟体内(^{2}H_{2}O)和(^{3}H)的同时周转率。我们的结果验证了红外吸光度在双标记水能量消耗测量中的应用，并表明体内(^{2}H_{2}O)和(^{3}H)的分馏系数没有差异。
