Donaldson K, Brown D M, Miller B G, Brody A R
Napier University, Edinburgh, Scotland.
Exp Toxicol Pathol. 1995 May;47(2-3):207-11. doi: 10.1016/S0940-2993(11)80316-7.
Rats were exposed, by inhalation, to target airborne fibre concentrations of 1000 f/ml (PCOM fibres by WHO criteria) of a long amosite asbestos sample and a vitreous fibre sample; the target was closely attained for both fibre samples. The size distributions of the two fibre samples was closely similar. Rats were placed in the chambers for 7 hours and then, following a further 16 hours in room air, were injected with bromo-deoxyuridine (BRDU). The presence of BRDU-positive cells in terminal bronchioles/alveolar ducts was assessed in blocks taken from various parts of the left lung, from apex to base. There were significant differences in the proliferative responses between animals but there were also significant differences between the treatments. Lungs from rats exposed to vitreous fibres showed no greater response than the controls, but there was a markedly greater proliferative response in the lungs of rats inhaling long amosite. There was a decreasing gradient of proliferative response from the apex of the lung to the base with all treatments. This could be explained by different degrees of deposition in different areas of the lung. Similar amounts of fibre accumulated in the lungs of rats exposed to the two fibre types and it is unlikely that dissolution could be important over the timescale used here. We conclude that, when amosite asbestos deposits in the lungs of rats it stimulates a proliferative response and that deposition of an equal number of similar-sized vitreous fibres has no effect.
将大鼠通过吸入暴露于长纤维铁石棉样本和玻璃纤维样本的目标空气传播纤维浓度1000 f/ml（根据世界卫生组织标准为PCOM纤维）；两种纤维样本均接近达到目标浓度。两种纤维样本的尺寸分布非常相似。将大鼠置于实验舱中7小时，然后在室内空气中再放置16小时后，注射溴脱氧尿苷（BRDU）。从左肺从尖部到基部的不同部位取材，评估终末细支气管/肺泡管中BRDU阳性细胞的存在情况。动物之间的增殖反应存在显著差异，但处理之间也存在显著差异。暴露于玻璃纤维的大鼠的肺与对照组相比没有表现出更大的反应，但吸入长纤维铁石棉的大鼠的肺中增殖反应明显更大。所有处理组从肺尖到肺底的增殖反应梯度均呈下降趋势。这可以用肺不同区域的不同沉积程度来解释。暴露于两种纤维类型的大鼠肺中积累的纤维量相似，并且在所使用的时间尺度上溶解不太可能起重要作用。我们得出结论，当铁石棉沉积在大鼠肺中时，它会刺激增殖反应，而等量大小相似的玻璃纤维沉积则没有影响。
