A LIGHT-MICROSCOPIC AUTORADIOGRAPHIC STUDY ON PROTEIN-SYNTHESIS IN PULMONARY CELLS OF AGING MICE

In the present study we first investigated the changes in protein synt hesis of respective cell types of mouse pulmonary alveoli from 16 days of fetal life to senility (postnatal 22 months) by using H-3-leucine light microscopic radioautography. The results revealed that the prote in syntheses in type epithelial cells, type II epithelial cells, inter stitial cells and endothelial cells in the mouse lung changed due to a ging. The protein synthesis of type I epithelial cells was the highest on postnatal day 1, increased again at 1 week after birth, and then d ecreased gradually to 22 months after birth with aging. The protein sy ntheses of type II epithelial cells, interstitial cells and endothelia l cells reached the highest level on fetal day 16, declined progressiv ely with age. and increased again at postnatal 1 week. and then decrea sed gradually from 2 weeks to senility. Our results suggest that the d ecreases in protein synthesis are correlated with the decremental chan ges in DNA and RNA synthesis in the lung with aging.