Objective To investigate the effects of different doses of radiation exposure on acute lung injury and mortality from decompression sickness (DCS) induced by rapid floating escape in rats.

Methods A total of 53 Sprague-Dawley rats were stratified in accordance with body weight and divided into 5 groups by using a random number table method. The groups were as follows: blank control group (10 rats), simple decompression group (10 rats), 4 Gy irradiation with decompression group (11 rats), 6 Gy irradiation with decompression group (11 rats), and 8 Gy irradiation with decompression group (11 rats). The animals in the irradiation groups were given different doses of ⁶⁰Co γ whole-body radiation and then exposed to decompression treatment (i.e., after staying at a depth of 57 m for 45 min, the rats were made to ascend quickly to atmospheric pressure within 37 s) 1 h after irradiation. The mortality rate, lung wet-dry weight ratio, degree of lung tissue pathological damage, and changes in levels of inflammatory factors and oxidative stress-related molecules in the alveolar lavage fluid were observed in each group of rats. Mortality rates among groups were compared using Chi-square test, while the remaining variables were analyzed using one-way ANOVA. Further comparison between two groups using LSD t-test.

Results Compared with that in the blank control group, the number of animal deaths and the lung wet-dry weight ratio increased in each experimental group, with the lung wet-dry weight ratio increasing significantly in the 6 Gy and 8 Gy irradiation with decompression groups (F=3.096, LSD-t=2.758, 2.959; all P<0.05). The pathological damage of lung tissues in each experimental group was evident, and those in the 6 Gy and 8 Gy irradiation with decompression groups were more significant among the irradiation groups. The interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and malondialdehyde (MDA) in the bronchoalveolar lavage fluid of each experimental group were significantly increased (F=45.680–78.270, all P<0.01), whereas superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were significantly decreased (F=35.720, 51.370; both P<0.01). Compared with that in the simple decompression group, the number of animal deaths in the 4 Gy and 8 Gy irradiation with decompression groups increased, but no statistical difference was noted in the mortality rate (χ²=7.925, P>0.05). Although the lung wet-dry weight ratio of the rats in each irradiation group exhibited an upward trend, no statistically significant difference was found (LSD-t=0.901, 1.818, 2.020; all P>0.05). The pathological damage of lung tissues was aggravated to different degrees, and the damage degree of the 8 Gy irradiation with decompression group was the most serious. Inflammatory factors (IL-1β, IL-6, and TNF-α) and oxidative stress-related molecules (SOD, GSH-Px, and MDA) in bronchoalveolar lavage fluid changed significantly (LSD-t=3.081–8.265, all P<0.01). Among which, the 6 Gy irradiation with decompression group exhibited the most significant change.

Conclusions Nuclear radiation can worsen lung tissue inflammation and oxidative stress damage caused by rapid floating escape. Such effect is manifested as aggravated lung tissue pathological damage and increased mortality, increasing the risk of DCS caused by rapid floating escape.