RESUMO
Planned exposures of rodents to diesel exhaust required development of an exhaust generation and delivery system flexible enough to accommodate varied experimental designs. The features of the exposure system built to meet these needs are summarized. Essential aspects including both the exhaust dilution and delivery system and the computer monitoring and control functions are described. During the first 29 weeks of a study with target particle concentrations of 350, 3500, and 7000 micrograms/m3, the achieved values were 310, 3360, and 6830 micrograms/m3 with coefficients of variation of 23, 10, and 9%, respectively. The system has now operated reliably for more than 24 months.
Assuntos
Emissões de Veículos/toxicidade , Animais , Computadores , Equipamentos e Provisões , Gases/análise , Camundongos , Tamanho da Partícula , Ratos , Emissões de Veículos/análiseAssuntos
Pulmão/efeitos dos fármacos , Nitritos/efeitos adversos , Animais , Colágeno/análise , Feminino , Pulmão/análise , Pulmão/patologia , Masculino , Ratos , Fatores de TempoRESUMO
A multitiered inhalation exposure chamber was evaluated for use in aerosol toxicity studies by determining the uniformity of pulmonary deposition in 144 rats simultaneously exposed to 99mTc-CsCl aerosols. The activity median aerodynamic diameter and geometric standard deviation were 1.7-2.1 micron and 1.8 respectively. In one experiment, lung deposition of 99mTc in male and female rats was 728 and 544 nCi, respectively, after 130 min exposure to an aerosol concentration of 173 nCi/L. Analysis of variance revealed a significant effect of several factors on lung deposition. Animals housed on one side of the chamber had lung burdens 8-11% greater than those on the opposite side. Because an animal's location within the chamber had a slight effect on its lung burden of inhaled aerosol we recommend the rotation of animals among the chamber's six tiers during chronic aerosol toxicity studies. The overall coefficient of variation in lung burden was only 21% which is less than the variability reported in small rodents given a nose-only aerosol exposure.
Assuntos
Câmaras de Exposição Atmosférica , Aerossóis , Animais , Feminino , Pulmão/metabolismo , Masculino , Ratos , Ratos Endogâmicos F344 , Fatores Sexuais , TecnécioRESUMO
Ammonia concentrations in 2.8 m3 chronic inhalation exposure chambers housing either 144 rats or 360 mice were measured by ion chromatography and chemiluminescence to evaluate chamber maintenance procedures. Variables included use of bacteriostatic cageboard, air flow rate, animal species, and age. Ammonia concentrations were lowered by using bacteriostatic cageboard and were inversely proportional to cageboard changing frequency and air flow rate.