EFFECTS OF SS320A, A NEW CYSTEINE DERIVATIVE, ON THE CHANGE IN THE NUMBER OF GOBLET CELLS INDUCED BY ISOPROTERENOL IN RAT TRACHEAL EPITHELIUM

We examined the effects of SS320A ((-)-(R)-2-amino-3-(3-hydroxypropylt hio)propionic acid), a new cysteine derivative, on the change in the n umber of goblet cells induced by isoproterenol in rat tracheal epithel ium. Four types of goblet cells were characterized in tracheal epithel ium according to their size and staining affinity with Alcian blue (AB )/periodic acid Schiff (PAS). When each rat was given a single daily i njection of isoproterenol (0.05 mg/kg, i.p.) for 14 days, a significan t increase was observed in AB/PAS-positive cells that were recognizabl e as goblet cells in tracheal epithelium. When SS320A (10-100 mg/kg, p .o.) or propranolol (1 mg/kg, s.c.) was administered before each injec tion of isoproterenol, the increase in the number of goblet cells indu ced by isoproterenol was significantly inhibited. There was no differe nce between male and female rats with regard to this inhibitory action . On the other hand, ambroxol, bromhexine, L-cysteine ethyl ester and S-carboxymethylcysteine (100 mg/kg, p.o., respectively), which are use d as expectorants, had no inhibitory effects on the isoproterenol-indu ced change in the number of goblet eels. Four metabolites (M1-M4) of S S320A in rats also failed to inhibit the change induced by isoproteren ol. These data suggest that SS320A itself may have a beneficial effect against mucus hypersecretion in chronic respiratory diseases.