Binder N D, Day D, Battaglia F C, Meschia G, Sparks J W
Department of Pediatrics, University of Colorado School of Medicine, Denver 80262.
J Appl Physiol (1985). 1991 Apr;70(4):1469-76. doi: 10.1152/jappl.1991.70.4.1469.
Previous studies have shown that venous lactate specific activity during arterial tracer lactate infusion differs from arterial lactate specific activity during systemic venous tracer lactate infusion. We performed paired experiments on chronically catheterized rabbits to compare left ventricular (LV) infusion with femoral venous (FV) infusion of L-[U-14C]lactate. Blood was sampled from both the femoral artery (FA) and right ventricle (RV) during both modes of infusion. The mean lactate specific activity measured for each combination (infusion site, sampling site) was (FV,FA) 4,380 +/- 452, (FV,RV) 4,370 +/- 471, (LV,FA) 4,364 +/- 239, and (LV,RV) 3,325 +/- 240 (SE) dpm/mumol. Lactate turnover calculated from the specific activity in the (LV,RV) mode was significantly higher than from the other three modes (P less than 0.001). Models of lactate turnover are discussed demonstrating that the (FV,FA) and analogous modes of infusion sampling measure the turnover rate of lactate molecules that cycle through the circulation. This estimate of turnover is less than the turnover rate by the whole organism to the extent that some produced lactate is metabolized locally without entering the general circulation. The turnover calculated by the (LV,RV) mode overestimates the turnover of circulating lactate and relates to whole body lactate turnover in a complex manner.
先前的研究表明，动脉注射示踪剂乳酸期间的静脉乳酸比活度与全身静脉注射示踪剂乳酸期间的动脉乳酸比活度不同。我们对长期插管的兔子进行了配对实验，以比较左心室（LV）输注L-[U-14C]乳酸与股静脉（FV）输注的情况。在两种输注模式下，均从股动脉（FA）和右心室（RV）采集血液。每种组合（输注部位、采样部位）测得的平均乳酸比活度为：（FV，FA）4380±452，（FV，RV）4370±471，（LV，FA）4364±239，以及（LV，RV）3325±240（SE）dpm/μmol。根据（LV，RV）模式下的比活度计算出的乳酸周转率显著高于其他三种模式（P<0.001）。文中讨论了乳酸周转模型，结果表明（FV，FA）以及类似的输注采样模式测量的是循环中乳酸分子的周转率。这种周转率的估计值低于整个生物体的周转率，因为部分生成的乳酸在局部代谢而未进入体循环。通过（LV，RV）模式计算出的周转率高估了循环乳酸的周转率，并且与全身乳酸周转率存在复杂的关系。
