Metabolism of vitamin A affected by prostaglandin F synthase in contractile interstitial cells of bovine lung.

Contractile interstitial cells (CIC), the major component of the alveolar septum of the bovine lung are enriched in prostaglandin (PG) F synthase (Fukui, M., Fujimoto, T., Watanabe, K., Endo, K., and Kuno, K. (1996) J. Histochem. Cytochem. 44, 251-257.). The enzyme catalyzes not only the reduction of PGD(2) and PGH(2) but also that of various carbonyl compounds (Watanabe, K., Yoshida, R., Shimizu, T., and Hayaishi, O. (1985) J. Biol. Chem. 260, 7035-7041). Here, we report that retinal (vitamin A-aldehyde) was reduced to retinol (vitamin A-alcohol) dose- and time-dependently by PGF synthase using NADPH as a cofactor. The Km value of PGF synthase for retinal was about 20 microM, a same order to that for PGH(2). The conversion of retinal to retinol was also observed in cultured CIC, as demonstrated by the greenish fluorescence characteristic of retinol. Thus, retinal might be one of the natural substrates for PGF synthase in vivo, and retinol synthesized from retinal in CIC may play physiological and pathological roles in the lungs. Copyright 2001 Academic Press.