Changes in rat lungs upon isolated chronic treatment with sulfur dioxide and in combination with ionizing radiation

In order to evaluate the influence of the isolated and combined sulfur dioxide pollution and ionizing radiation on certain biochemical, enzymic, cytologic and other parameters of the lungs, 250 male albino rats were examined. The chemical noxa was administered via inhalation at concentration of 21,2 mg/m3, during 5 h daily, 5 times weekly, over a period of 4 months. After that treatment the animals were subjected to a single whole-body irradiation with dose rate of 2 and 4 Gy on a linear accelerator with photon energy 9 MeV and radiation power 2 Gy/min. The determination of the different parameters were carried out on the 1st, 5th, 15th, 30th and 60th post-irradiation days. It was established that the sulfur dioxide decreased the cell amount of the bronchoalveolar lavage fluid. The both factors increased the activity of lactate dehydrogenage, acid phosphatase and alkaline phosphatase at the early stages and decreased the activity of angiotensin converting enzyme. The data about the changes of the connective tissue matrix were obtained according to the hydroxyproline content and the collagenase activity