Dual pathway clearance of /sup 99m/Tc-DTPA from the bronchial mucosa
Many studies have reported clearance rates of 99mTc-DTPA from the alveolar epithelial surface, but few have measured clearance of this solute from the bronchial mucosa. Those that have attempted such measurements have discounted the possibility that 99mTc-DTPA may be removed from the bronchial airways by mucocilliary transport as well as by absorption through the epithelium. This study was designed to better approximate the rate of 99mTc-DTPA absorption across the bronchial epithelium by correcting the measurements of total 99mTc-DTPA clearance for mucus transport. On two separate study days, each normal, nonsmoking subject (n = 8) breathed an aqueous aerosol (2.0 microns MMAD, sigma g = 2.0) containing 99mTc bound to DTPA or human serum ablumin (HSA) (a relatively nonpermeable solute that is cleared only by mucus transport over the period of measured clearance) while seated in front of a gamma camera. Breathing pattern was standardized to produce a similar central deposition of particles on both study days. From measurements of retention versus time over a 1-h period, exponential rate constants (Ktot and Km) were determined for the clearance of 99mTc-DTPA and 99mTc-HSA, respectively. By modeling the airways as a single compartment with two possible routes of clearance, we determined the permeability rate constant, Kp, as Ktot minus Km. Results showed that mucus clearance (Km) accounted for two thirds of the total rate of 99mTc-DTPA clearance (Ktot) (mean Ktot = 0.00985, Km = 0.00698, and Kp = 0.00287/min).
- Research Organization:
- SUNY at Stony Brook, New York, NY (USA)
- OSTI ID:
- 6080866
- Journal Information:
- Am. Rev. Respir. Dis.; (United States), Vol. 139:5
- Country of Publication:
- United States
- Language:
- English
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DTPA
LUNG CLEARANCE
MUCOUS MEMBRANES
PERMEABILITY
ABSORPTION
AEROSOLS
BIOLOGICAL HALF-LIFE
BIOLOGICAL PATHWAYS
BRONCHI
CELL MEMBRANES
EPITHELIUM
ISOMERIC NUCLEI
MAN
RETENTION
TECHNETIUM 99
TRACER TECHNIQUES
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHELATING AGENTS
CLEARANCE
COLLOIDS
DISPERSIONS
DRUGS
EXCRETION
HOURS LIVING RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PRIMATES
RADIOISOTOPES
RADIOPROTECTIVE SUBSTANCES
RESPIRATORY SYSTEM
SOLS
TECHNETIUM ISOTOPES
TISSUES
VERTEBRATES
YEARS LIVING RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques