Wisneski J A, Stanley W C, Neese R A, Morris D L, Brooks G A, Gertz E W
Department of Medicine, University of California, San Francisco.
Horm Metab Res. 1990 Mar;22(3):157-62. doi: 10.1055/s-2007-1004874.
Controversy exists in the literature concerning the correct infusion and sampling sites in studies measuring substrate turnover rates. To investigate this problem, we examined the results obtained with various infusion and sampling sites in 7 anesthetized dogs. [1-14C]lactate was infused by a primed continuous infusion method in three different sites (the left ventricle, ascending aorta, and the aortic arch) in a sequential fashion; samples were obtained simultaneously from five sites (femoral artery, carotid artery, pulmonary artery, superior vena cava and inferior vena cava) for each of the three different infusion sites. [U-13C]lactate was also infused in a femoral vein and simultaneous samples were obtained in the carotid artery and femoral artery for analysis of the stable isotope. [14C]lactate analysis demonstrated that infusion of the tracer into the left ventricular chamber resulted in a uniform distribution in the systemic circulation. Infusion into the ascending aorta near the aortic valve resulted in uniform distribution of tracer in four out of five experiments. Tracer infusion into the aortic arch resulted in nonuniform systemic distribution of tracer. The [U-13C]lactate results showed that infusion into the femoral vein gives uniform systemic distribution, similar to that observed with left ventricular infusion. The pulmonary artery lactate specific activities varied from those in the superior vena cava. Thus, this study shows that the tracer must be infused in the left ventricle or upstream from this chamber to obtain optimal systemic distribution. Vena caval sampling, especially superior vena caval sampling, will not give a consistent mixed venous concentration of the lactate tracer. Therefore, aortic tracer infusion with vena caval sampling may lead to errors in determining substrate turnover values.
在测量底物周转率的研究中，关于正确的输注和采样部位，文献中存在争议。为了研究这个问题，我们检查了7只麻醉犬在不同输注和采样部位所获得的结果。通过预充连续输注法，以顺序方式在三个不同部位（左心室、升主动脉和主动脉弓）输注[1-14C]乳酸盐；对于三个不同的输注部位，同时从五个部位（股动脉、颈动脉、肺动脉、上腔静脉和下腔静脉）采集样本。还通过股静脉输注[U-13C]乳酸盐，并同时在颈动脉和股动脉采集样本用于稳定同位素分析。[14C]乳酸盐分析表明，将示踪剂输注到左心室内会导致其在体循环中均匀分布。在五个实验中的四个实验里，将示踪剂输注到主动脉瓣附近的升主动脉会导致示踪剂在体循环中均匀分布。将示踪剂输注到主动脉弓会导致示踪剂在体循环中分布不均。[U-13C]乳酸盐的结果表明，输注到股静脉会产生均匀的体循环分布，类似于左心室输注时观察到的情况。肺动脉中乳酸盐的比活性与上腔静脉中的不同。因此，本研究表明，示踪剂必须输注到左心室或该腔室的上游部位，以获得最佳的体循环分布。腔静脉采样，尤其是上腔静脉采样，不会给出一致的乳酸盐示踪剂混合静脉浓度。因此，通过腔静脉采样进行主动脉示踪剂输注可能会导致在确定底物周转率值时出现误差。
