Retention of soluble 99mtc-dtpa in the human lung: 24 hr post
-deposition.
Foster, Wm. Michael, Pamela T. Stetkiewicz, and Arthur N. Freed.
Department of Environmental Health Sciences, School of Hygiene and
Public Health, The Johns Hopkins University, Baltimore, MD 21205
APStracts 3:0566A, 1996.
Clearance of low molecular weight solutes, e.g., radiolabeled chelate
diethylentriamine-pentaacetate (DTPA), across epithelial surfaces of
distal airways and the lung parenchyma is a broadly used technique to
assess epithelial integrity. It has been generally assumed that
clearance of solute follows a simple first-order process and that
DTPA clearance through the respiratory epithelium and into blood and
lymphatic channels is complete within a few hours. Using _-camera
imaging and a radiolabeled aerosol of 99mTc-DTPA, we observed in 8
healthy subjects lung retention of radioisotope _24 hr post
-deposition of the 99mTc-DTPA. Residual lung retention at the 24 hr
endpoint averaged 6.0 +/-1.8% (+/-SD) of the amount of radioisotope
initially deposited in the lung. This suggests that for normal,
healthy subjects a small amount of the 99mTc radioisotope, either in
a dissociated or chelated form, is non-permeable or slowly cleared
from respiratory tisssues.
Received 1 August 1996; accepted in final form 26 November 1996.
APS Manuscript Number A741-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996