Irreversible Pulmonary Changes Induced in Rat Lung by Dust Overload

Abstract

The objective of this study was to investigate whether the effects of dust overload are reversible upon cessation of subchronic exposure to test toner. Female ratswere exposed 6hr/day, 5 days/week for 3 months to a test tonerat 0, 10, and 40 mg/m3. The retained quantity oftest toner in the lungs at the end ofexposure was GA and 3.0 mg for the low and high exposure groups, respectively. Fifteen months later, the corresponding values mere 0.12 and 2.65 mg in the lungs. Alveolar clearance oftracer aerosols as weil as cytologic and enzymatic parameters in the bronchoalveolar fluid was investigated at the end ofexposure and subsequently up to 15 months later. The alveolar dearance of RFe203, 51Cr-polystyrene, and 'Sr-polystyrene tracer aerosols was slightly retarded at the low and substantially impaired at the high exposure level. At the low exposure level, there was some recovery in the clearance behavior up to 6 months after exposure In contrast, at the high exposure level there was no indication of a reversal of the impaired clearance. For the jS glucuronidase activity and the number of polymorphonuclear cells, the pattern of the effects was similar to the effects on the half-timne tracer particle clearance. In conclusion, the dust overload at a lung burden of3 mg test toner in rats was persistent for at least 15 months after termination of exposure.

RELATIONSHIP BETWEEN ENZYMATIC MARKERS OF PULMONARY CELL DAMAGE AND CELLULAR PROFILE: A Study in Bronchoalveolar Lavage Fluid

“…Many studies in animals report the relationship between LDH and pulmonary disorders [ 13,17,[23][24][25][26][27][28][29][30][31] . Only a few studies on humans have been carried out to investigate the relation between LDH an pulmonary disorders.…”

Nanoparticles-A Thoracic Toxicology Perspective

“…Nano-size CB has been intensively studied with regard to the issue of low toxicity dust and the confounding effect of rat lung overload 64-67. In view of the very high surface area per unit volume of NP and the identification of surface area as the driver for overload,68-70 attention has been focused on the nanoparticulate form of these nuisance dusts.…”

Inhalation of Poorly Soluble Particles. Ii. Influence of Particle Surface Area on Inflammation and Clearance

“…Changes in chemokine levels in the centriacinar region could impact on the chemotactic gradient. The accumulation of chemokines in the centriacinar region would be expected to act to retain macrophages, regardless of their particle load, and to prevent their migration to the mucociliary escalator (Bellmann et al, 1992). Thus a scenario of accumulating inflammatory cells, retention of particles, and release of proinflammatory mediators can be envisaged.…”