Exposure to crystalline silica or treatment with chlorphentermine increases vitamin E levels in rat alveolar lavage materials.
Miles-PR; Bowman-L; Reasor-MJ
J Toxicol Environ Health, A 1996 Dec; 49(5):511-523
Previous studies have shown that vitamin E may be an integral part of lung surfactant and may function to protect this material from oxidant damage. Therefore, we measured the vitamin E levels in alveolar lavage materials from rats exposed to crystalline silica or treated with chlorphentermine (CP) , two treatments that are known to increase surfactant phospholipids (PL) by different mechanisms. Silica exposure leads to increased PL synthesis, and CP treatment causes a reduction in PL degradation. Two different silica preparations, HCl-washed and unwashed silica, were used because exposure to each of them leads to different degrees of phospholipidosis. Exposure to HCl-washed silica results in a more than 17-fold increase in lavage PL and protein levels and a 12.2-fold increase in the amount of vitamin E. Exposure to unwashed silica leads to an approximately 7-fold increase in PL and proteins and a 5.8- fold increase in lavage vitamin E. Following treatment of rats with CP, there is a 15- to 19- fold increase in lavage PL and proteins and a 13.6-fold increase in vitamin E. When the results are expressed as micrograms vitamin E per milligram of lavage PL or protein, there is not much difference between controls and each treatment group. Because surfactant synthesis occurs in the endoplasmic reticulum, we also measured vitamin E in lung microsomes. Both silica exposure and CP treatment also lead to 1.8- to 2.5-fold increases, respectively, in the lung microsomal levels of vitamin E. These results demonstrate that alveolar lavage vitamin E levels are elevated along with lavage PL and proteins, and lung microsomal vitamin E levels are increased following exposure of rats to silica or treatment of the animals with CP.
Silicates; Silicon-compounds; Vitamins; Lung-cells; Lung-fibrosis; Lung-function; Lung-irritants; Laboratory-animals; Pulmonary-disorders; Pulmonary-function; Pulmonary-system
Philip R. Miles, PhD, NIOSH, Physiology Section, Rm. 207, 1095 Willowdale Road, Morgantown, WV 26505
Journal of Toxicology and Environmental Health, Part A: Current Issues