Catabolism of collagen and non-collagen protein in the rat uterus during post-partum involution

Publisher Website
Google Scholar
Abstract
The metabolic breakdown of collagen and non-collagen protein was studied in the rat uterus undergoing post-partum involution. Collagen disappeared from the uterus at a rate proportional to the surface area of the fibre, after an initial lag period of about 18 hr. The process was complete by 100 hr. post partum. A small, but significant, increase in the amount of saline-soluble collagen occurred, reaching a peak at 40-50 hr. post partum. Small peptides containing hydroxyproline did not increase in amount during involution. Free hydroxyproline doubled in amount and increased sixfold in concentration, reaching a peak about 60 hr. post partum. This free hydroxyproline appears to leave the uterus through the blood stream. Only a small increase in urinary-peptide hydroxyproline could be detected. Non-collagen protein and wet weight decreased at first-order rates with half-lives of 34-38 hr. Free proline and glycine decreased at significantly slower rates (49 and 66 hr.). The involuting uterus contains two catheptic activities. The cathepsin having optimum pH 3.5 can effect almost complete digestion of uterine collagen at 37[degree] in vitro. Imino- and imido-dipeptidase activities were one-third of those found in rat liver.