Changes in levels of cellular retinol- and retinoic-acid-binding proteins of liver and lung during perinatal development of rat.

Abstract

Cellular retinol-binding protein and cellular retinoic-acid-binding protein, candidates for mediating the action of vitamin A, were present in tissues of the fetal rat. Cellular retinol-binding proteins were still present in most tissues of the adult, but the retinoic-acid-binding protein was not detected in some, including lung, liver, intestine and kidney. During perinatal development of lung the level of cellular retinol-binding protein remained relatively constant while the level of the cellular retinoic-acid-binding protein peaked at 10 days postnatally, then declined. It was not detectable in lung tissue from 21 day old rats. In liver the retinoic-acid-binding protein was not detectable later than 5 days postnatally, while the level of the cellular retinol-binding protein rose sharply near birth, declining only after 21 days to the lower adult levels. The variations observed in the levels of the 2 binding proteins suggest different and changing requirements for retinol and retinoic acid in organ development and maturation.