亜硫酸ガスの幼弱動物の呼吸器に及ぼす影響に関する実験研究 -とくに肺病理組織学的検討と, 換気力学的検討-

抄録

In order to examine the effects of SO₂ inhalation on infant animals, experiments were designed to start on CF₁ mice of 1 week and rabbits of 1 month after birth. 1 to 10ppm SO₂ gas and saline aerosol were inhaled for one hour every day. 6 to 9 infant mice from the same parents were divided into SO₂ and control groups and mice of each group were examined pathologically after exposed peroid for 1 to 12 weeks. Rabbits were also divided into SO₂ and control groups, and each group consisted of 4 infant rabbits and respiratory flow-resistance by oscillation method and histo-pathological changes were examined after exposed period for 1 to 11 months.
SO₂ gas of 1-10ppm was found to act on the lungs of young mice as follows: After 2 weeks of exposure, dilatation of the alveoli and diffuse thickening of the alveolar septa were noticed. After 4 weeks of exposure, mononuclear cells infiltration around the bronchi and epitherial degeneration of the bronchi were revealed. After 7 weeks of exposure, mononuculear cells infiltration in the perivascular areas and exudative cells in the alveoli were found. After 8 weeks of exposure, nodular formation on the alveolar septa appeared. Among these changes, the infiltration of mononuculear cells around the bronchi and the pulmonary vessels increased up to 10 weeks after the start of SO₂ exposure, but did not increase apparently after 10 weeks' exposure. Althought these histopathological changes showed somewhat similar to those seen in the adult animals, it is noteworthy to point out that they appeared in relatively early stage after the SO₂ exposure in the young animals in spite of inhalation of the low concentration (1 to 10ppm) of SO₂.
During the experiments of rabbits, the weight gain with the growth did not appear to be influenced by the exposure of SO₂ gas. The Breathing frequency trended to lower in the SO₂ groups than in the control groups without any correlation to the exposed period. The total respiratory flow resistance decreased with the growth in control groups, and seemed to be dependent on the lung volume. While in the SO₂ groups, after 4 to 8 months' exposure, values of the resistance were above the range of the control groups. After 9 to 11 months' exposure, however, the flow resistance were not different between the two groups. Shortly after an adiministration of hydrochloric-L-isoproterenol, the total respiratory flow resistance reacted to decrease in the SO₂ groups under 5 to 8 months' exposure. These effects were not observed after 8 months' exposure. The histopathological changes seen in the rabbits were alveolitis and interstitial inflamation and were similar to those found in the experiments of the mice. These kinds of changes were also observed in the control groupss but in lower degree. Although contamination by the viral or bacterial infection can not be completely excluded, the pathological changes in the SO₂ groups which were more severe and irreversible seems to be responsible to the influence of the SO₂ gas.