Sequential changes of the activities of the dog tracheal secretory cells caused by intraduodenal application of brovanexine

: The effects of brovanexine (BvX) on secretory activities of tracheal secretory cells and on behavior of mucus glycoprotein in these cells were investigated histologically and histochemically using the biopsy technique. When BvX was given at 10 or 20 mg/kg intraduodenally to anesthetized dogs, the thickness of the acini of submucosal glands (SG) and the ratio of the acinar inner diameter to the tracheal wall thickness (A1WR) markedly increased dose-dependently after 2 to 6 hr. The numbers of goblet cells (GC) and glandular cells showing a stain index B&P with a combination of alcian blue (AB) at pH 2.5 or pH 1.0 and periodic acid-Schiff (PAS) were reduced dose-dependently after 1 to 6 hr, while the number of cells with a stain index R were increased. Both the BvX-induced histological changes in SG and histochemical changes in GC and SG reached a peak after 4 hr. These histological and histochemical changes were also found for the BR-227-, a metabolite of BvX, and bromhexine (BH)-treated groups. BR-227- or BH-induced histological changes were to the same degree as those induced by BvX, but BvX- or BR-227-induced histochemical changes were slighter than those induced by BH. The total number of GC stained positively with a combination of AB at pH 2.5 and PAS was unaffected by BvX or BH treatment, while BR-227 tended to decrease it. These findings suggest that BvX both has a secretagogic action selectively on SG and a mucolytic action toward acid glycoprotein in granules of secretory cells in vivo, and these actions are durable.