Katz J, Wolfe R R
Cedars-Sinai Medical Center, Los Angeles, CA 90048.
Metabolism. 1988 Nov;37(11):1078-80. doi: 10.1016/0026-0495(88)90071-6.
It has been shown in studies of turnover in vivo of lactate and several amino acids that the specific activity in blood depends on the site of tracer administration and of sampling. Theoretical and experimental studies have established that to obtain valid estimation of turnover in vivo for these compounds, tracers should be administered into the left heart, ideally the ventricle, and blood sampled from the right heart, ideally the pulmonary artery. Alternately, tracer may be infused into the pulmonary artery and blood sampled from the right ventricle. The insertion of such in-dwelling catheters for turnover studies is difficult in small animals and not justified on ethical grounds in humans. We describe here a method to calculate valid turnover rates when the tracer is administered in a peripheral vein and blood sampled from any peripheral artery. In humans, infusion into a hand vein and sampling from the contralateral heated hand vein can be used. The true turnover rate can then be calculated if the cardiac output is determined. Several noninvasive methods for the determination of cardiac output are available. Thus a correct estimate, avoiding major catheterization, for turnover for many blood-borne compounds is possible.
乳酸和几种氨基酸在体内周转的研究表明，血液中的比活性取决于示踪剂给药部位和取样部位。理论和实验研究已证实，为了有效估计这些化合物在体内的周转情况，示踪剂应注入左心，理想情况下是心室，血液应从右心，理想情况下是肺动脉采集。或者，示踪剂可注入肺动脉，血液从右心室采集。在小动物中插入这种用于周转研究的留置导管很困难，而且从伦理角度考虑在人体中也不合理。我们在此描述一种方法，当示踪剂在外周静脉给药且从任何外周动脉采集血液时，计算有效的周转率。在人体中，可将示踪剂注入手部静脉，并从对侧加热的手部静脉取样。如果测定心输出量，便可计算出真实的周转率。有几种非侵入性测定心输出量的方法。因此，避免进行大型插管操作而对许多血源化合物的周转情况进行正确估计是可能的。
