Jones C D, Bull J R
Res Vet Sci. 1987 Jan;42(1):82-91.
Two groups of three calves were exposed to monodisperse aerosols of radiolabelled polystyrene spheres measuring 3.3 microns in aerodynamic diameter (SD 0.3 micron). Although the spheres preferentially deposited in the trachea and major bronchi, 72 per cent of the total radioactivity deposited was found in lung tissue beyond the major bronchi. Mean alveolar deposition, estimated from the end retention value after mucociliary clearance, was 34 per cent in the group of bull calves and 52 per cent in the group of heifer calves. Alveolar deposition increased from 47 to 56 per cent (P less than 0.05) in heifer calves treated with oestradiol. Mucociliary clearance of the spheres was unaffected by repeated exposure to the experimental aerosol and the overall mean mucociliary clearance rate constant was 1.28 (+/- 0.43) h-1 (half-life 32 minutes). Clearance curve profiles tended to be characteristic for individual calves but variation in mucociliary clearance rates within calves was high and on occasions clearance rate inexplicably fell to 10 to 50 per cent of the maximum achievable value for the calf. Neither mucociliary clearance rate nor alveolar deposition was affected by a change in climate from 14 degrees C, 87 per cent relative humidity to 5 degrees C, 75 per cent relative humidity. Both alveolar deposition and mucociliary clearance of the spheres could be manipulated using a beta-adrenergic treatment.
两组三头小牛暴露于空气动力学直径为3.3微米（标准差0.3微米）的放射性标记聚苯乙烯球体的单分散气溶胶中。尽管这些球体优先沉积在气管和主支气管中，但在主支气管以外的肺组织中发现了72%的总沉积放射性。根据黏液纤毛清除后的最终保留值估算，公牛犊组的平均肺泡沉积率为34%，小母牛犊组为52%。用雌二醇处理的小母牛犊的肺泡沉积率从47%增加到56%（P<0.05）。球体的黏液纤毛清除不受重复暴露于实验性气溶胶的影响，总体平均黏液纤毛清除率常数为1.28（±0.43）h-1（半衰期32分钟）。清除曲线特征往往因个体小牛而异，但小牛体内黏液纤毛清除率的变化很大，有时清除率会莫名其妙地降至小牛最大可达值的10%至50%。从14摄氏度、相对湿度87%变为5摄氏度、相对湿度75%的气候变化对黏液纤毛清除率和肺泡沉积均无影响。使用β-肾上腺素能治疗可以控制球体的肺泡沉积和黏液纤毛清除。
