Tobacco Documents Online

AL'l'ERA'1'IONS IN LUNG PARtiNC1lYAlf1 I'OLLOWING EXE'tiRIM[:N'I'AL CHRONIC DNt1ALA'I'ION Or TOBACCO SMOKE ~ Hunter Nicholas, FKau1 Davies, Cl inton Sornbc*rger and Gary Iluher Ilarvarcl hicdical School, 13oston, Massachusetts / Despite the prevailing epidemiologic data associating tobacco cigarette smoking with chronilc pulmonary disease, little or no cause-andi-effect evidence has emerged tA link tobacca directly to parenchymal alterations in the lung. To study this probeimi, we quantified alterations in pulmonary parenchyma distal to the terminal airways by light microscope stereology in lungs of male CD rats exposed daily for 6 months to whol'e tobacco smoke. Experimental smoke inhalations were performed three times per day in a tobacco deposition dose equivallent to approximately 11-2 packs of unfiltered cigarettes per day in man. The lungs were then inflated with glutaraldehyde for 24 hours at a constant pressure of 25 cm water and lung volumes determined. Lung sections were analyzed on an automated stage sampling microscope by point and inter- section counting with a Weibel test lattice. The volume density (Vv) of parenchymatous tissue distal' to the terminal airways of control and smoke- exposed lungs, respectively, was 0.13 and 0.11, (P<.01), the Vv of parenchymatous air space was 0.87 and 01.89 (P<.01); and the surface density of alveolar epithelium was 0.050 and 0.044 uz/u3. These data indicate a decrease of 210 in parenchymous tissue and a 12% decrease in the alveolar surface area. Topographical analysis of the alveoli revealed that the numerical density of Type I pnetnnocytes was 35 an& 23 per 106 u3 (P<.Ol) in control and smoke- exposed lungs, respectively. These experiments demonstrate that a loss or destruction of lung parenchyma distal to the terminal airways occured following experimental exposure to tobacco smoke for six months duration.