MEASUREMENT OF METABOLIC EXTRACTION OF TRACERS IN THE LUNG USING A MULTIPLE INDICATOR DILUTION TECHNIQUE

  • 1 January 1984
    • journal article
    • research article
    • Vol. 25  (1) , 31-37
Abstract
Selective pulmonary uptake of many natural and synthetic substances has been demonstrated by physiologists and pharmacologists using isolated perfused lung preparations or invasive techniques. It is difficult to relate these laboratory studies to disease processes and to the study of problems encountered in a [human] clinical environment. A noninvasive method was developed for studying the pulmonary uptake of tracer substances using available radiotracers, gamma cameras and computers that would give information similar, if not identical, to that from the invasive laboratory methods, and that could be applied in a clinical setting. The multiple-indicator dilution technique, modified for external counting, is well suited for such studies of pulmonary uptake of tracer substances. 99mTc microsulfur colloid (99mTc micro SC) was used as an intravascular reference tracer, N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) as a cellular test tracer amine and 111In DTPA [diethylenetriaminepentaacetate] as an extracellular tracer [in dogs]. Calculated 1st-pass lung uptakes of 123I-IMP and 111 DTPA were 0.92 .+-. 0.04 and 0.17 .+-. 0.04, respectively, relative to the reference tracer. Using this approach, the 1st-pass pulmonary extraction of a variety of radiolabeled test tracers can be measured in a clinical environment in a variety of physiologic settings.