Effects of Sulfuric Acid on Ferret Respiratory Tract Clearance

Abstract

I NTRO D U CTI 0 NMany animal species have been successfully used as models by toxicologists in respiratory tract deposition and clearance studies. Among these are rabbits (Chen and Schlesinger, 1983;Schlesinger, 1990), dogs (Wolff et al., 1981), donkeys (Schlesinger et al., 1979), rats (Kenoyer et al., 1981;Mannix et al., 1983), sheep (Sackner et al., 1981, mice (Fairchild et al., 1975), guinea pigs , and hamsters (Harbison and Brain, 1983). When selecting an animal model for a particular clearance study, the investigators must consider many practical factors, including the cost of purchasing and housing (feeding, etc.) the animals, the number of animals that would be required to observe a significant physiological effect, and the ease of performing the measurements. Most im- portantly, the anatomical and physiological similarity of the respiratory system of the animal to the human respiratory system, and the availability of healthy animals, are key features for many studies.

Effects of nitrogen dioxide on respiratory tract clearance in the ferret

“…The clearance data reported here are in good agreement with that previously reported for the normal young adult ferret (Mannix et al, 1991), and are distinctly different from the clearance patterns of rodents as reported by others (Bailey et al, 1989) and measured in our laboratory using the same methods as in the present work (Kenoyer et al, 1981;Mannix et al, 1982). Therefore, it is of limited value to compare directly the slopes found for particle clearance from the head and thoracic regions among the various species.…”

“…The purified air-exposed group had a clearance pattern very similar to that measured in older control ferrets in a previous study (Mannix et al, 1991). As in the earlier study, about 20% of the tracer radioactivity was presumed to be deposited on slow-clearing epithelium, as evidenced by the time-zero intercept of the slow-clearing component.…”

“…The ferret was chosen as the animal model because its lung structure in many ways resembles that of the human more than do the lung structures of other species used in toxicologie studies (Phalen and Oldham, 1983;Oldham et al, 1990). Additionally, in a previous study the ferret thoracic clearance pattern was found to be quite similar to that of humans (Mannix et al, 1991). Because the ferret grows very rapidly, from about 15 g at birth to as much as 1 kg at 20 wk, an exposure regimen spanning the period of most rapid lung maturation could be accomplished in a reasonable time frame.…”

“…Clearance was measured by monitoring the disappearance of inhaled radiolabeled particles from the head and thoracic regions as previously described (Mannix et al, 1991). In brief, 51 Cr-labeled polystyrene latex microspheres were prepared (Hinrichs et al, 1978) and the ferrets were allowed to inhale an aerosol of the particles for a period of 30 min using a previously described nose-only exposure apparatus (Raabe et al, 1973).…”

“…The total radioactivity deposited in the respiratory tract was approximately 1 /¿Ci per ferret. The distribution and quantitation of radioactivity was determined using two collimated sodium iodide scintillation detectors positioned to separately detect radiation from the head and thoracic regions (Mannix et al, 1991). The head airways region extended from the tip of the nose to the midpoint of the trachea, while the thoracic region included the lower half of the trachea and the lungs.…”