EMPHYSEMA AS A RESULT OF INVOLUNTARY EXPOSURE TO TOBACCO-SMOKE - MORPHOMETRICAL STUDY OF THE RAT

Several attempts have been made to describe the relation that exists b etween tobacco smoke and emphysema, through different experimental mod els of the active smoker. Despite the negative effects that involuntar y inhaled tobacco smoke can have on the lung, no experimental model of the passive smoker has been proposed. In this study, an experimental model of the involuntary smoker is described and the following hypothe sis proposed: Passive exposure to tobacco smoke produces morphological alterations in the rat lung, which are compatible with emphysema. Emp hysema will be considered to have been caused when enlargement of the distal airspaces of the lung and tissue destruction are demonstrated. Sixty Wistar rats were used, divided into two groups: a control group and a group that was passively exposed to tobacco smoke for a period o f 3 months. A morphometrical study of the lung was performed using a c omputerized system. To demonstrate enlargement of the distal airspaces of the lung, the following variables were quantified: alveolar chord and mean linear intercept index (Lm); tissue loss was demonstrated by means of the quantification of the variables: tissue density, internal alveolar perimeter (IAP), and wall thickness (WT). The elastic fiber was also quantified. The animals that were exposed to tobacco smoke di splayed the following significant alterations (p<.05): an increase of the alveolar chord and of the Lm, a decrease of the IAP, WT, and tissu e density, and a loss of the elastic component of the lung. On the bas is of these findings, it is concluded that the rats that were exposed in a passive way to tobacco smoke display morphological pulmonary alte rations that are compatible with the definition of emphysema.