AIM The purpose is to investigate the prophylactic effects of
dibutyryl cAMP on the pulmonary smoke
inhalation injury in
rats. METHODS The water content of lungs, the pulmonary microvascular permeability(PMVP), the level of cAMP, the activity of myeloperoxidase(MPO), and the content of malondialdehyde (MDA) were determined with wet to dry weight ratio, evans blue fluorescence, radioimmunoassay, hydrogen peroxide reduction technique, and thiobarbituric acid spectrophotometry, respectively. RESULTS The PMVP was enlarged obviously at 2 h and reached the highest at 6 h post-smoke-
inhalation injury in rats. The water content of lungs, the activity of myeloperoxidase(MPO) and the content of malondialdehyde (MDA) were increased greatly at the same time. Respiratory failure occurred. On the contrary, the level of cAMP was decreased progressively, which began at 2 h, and reached the lowerest at 6 h(P<0.01) post-smoke-inhalation injury in rats.
Dibutyryl cAMP(Db-cAMP) ip inhibited the enlargement of PMVP and the increase of water content of lungs, reduced the leukocyte infiltration in injuried lung tissues, and alleviated peroxidation injury dose-dependently. Isoprenaline (Iso) ip had the similar effects. CONCLUSION Db-cAMP had prophylactic effects on the pulmonary injury post-smoke-inhalation in rats , the mechanisms of which were related to the decrease of leukocyte infiltration in injuried lungs ,the alleviation of peroxidation and the reduction of PMVP.