[Changes in glycoprotein composition of the tracheal submucosal glands caused by S-carboxymethylcysteine treatment].

The mechanism for the expectorant effect of S-carboxymethylcysteine (S-CMC) was investigated histologically and histochemically using isolated canine trachea. Following S-CMC treatment, the number of total glycoprotein-containing goblet cells (GC) did not change. The numbers of acid glycoprotein (AGP)-, neutral glycoprotein (NGP)-, and sulphated glycoprotein (SGP)-containing GC were also unaltered in a concentration range of 10(-7) to 10(-4) M. On the other hand, the ratio of the acinar inner diameter of submucosal glands (SG) to the tracheal wall thickness significantly increased with 10(-5) and 10(-4) M S-CMC, and the thickness of the acini of SG significantly decreased with 10(-4) M S-CMC. Although the ratio of the numbers of AGP-to NGP-containing glandular cells and AGP content in the cells did not change, the number of SGP-containing glandular cells significantly decreased with 10(-4) M S-CMC, and SGP content in the cells significantly decreased concentration-dependently High concentrations (10(-5) and 10(-4) M) of S-CMC produced increases in total saccharide, protein and N-acetylhexosamine concentrations in the incubation fluid. These findings suggest that S-CMC has a selective secretagogic action on SG, and an action which alters the composition of AGP, a chief viscous factor, in the mucous granules of SG. The expectorant effect of this agent may, at least in part, be ascribable to these actions.