Initiation of human parturition. XI. Lysosomal enzyme release in vitro from amnions obtained from laboring and nonlaboring women.

In the present investigation, we sought to ascertain whether an alteration in the physiology of amnionic lysosomes could be demonstrated in association with normal human labor at term. We reasoned that perturbation of the lysosomes of amnion would be associated with a greater rate of release of known lysosomal marker enzyme activity from this tissue. In order to investigate this possibility, we employed discs of amnion tissue which were incubated in medium containing sucrose (0.25M). We observed that the rate of release of lysosomal marker enzyme activity, N-acetyl glucosaminidase, into the incubation medium from amnion tissue obtained from laboring women was greater than the rate of release of the same enzyme activity from amnion tissue obtained from women who were not in labor. During incubation, there was no detectable release of lactate dehydrogenase, a cytosolic marker enzyme, which attests to the viability of the amnion tissue during the experiment. These findings are consistent with the view that there is an alteration in the physiology of lysosomes of the amnion associated with human labor at term, a finding which is supportive of a role for lysosomes of the human fetal membranes in the initiation of human parturition.