Effect of pilocarpine on behavior of mucus glycoproteins of canine tracheal secretory cells.

Behavior of mucus glycoproteins in tracheal secretory cells after treatment with pilocarpine was investigated histologically and histochemically using the isolated canine trachea. Following pilocarpine treatment, the number of total and neutral glycoprotein-containing goblet cells was reduced concentration-dependently. The number of acid glycoprotein (AGP)-containing goblet cells was not altered with 10(-7) and 10(-6) M pilocarpine, but significantly decreased with 10(-5) and 10(-4) M pilocarpine. The thickness of the acini of submucosal glands significantly decreased, and the ratio of acinar inner diameter to tracheal wall thickness increased in 10(-5) and 10(-4) M pilocarpine. AGP content in glandular cells increased in 10(-7) and 10(-6) M pilocarpine, but markedly decreased at concentrations of 10(-5) and 10(-4) M. Pilocarpine treatment caused an increase in N-acetylhexosamine concentration in the incubation fluid. Total saccharide concentration in the incubation fluid decreased in 10(-7) and 10(-6) M pilocarpine, but was not apparently altered at concentrations of 10(-5) and 10(-4) M. These findings suggest that lower concentrations of pilocarpine stimulate synthesis of AGP in goblet and glandular cells much more preferentially than it stimulates discharge of AGP from the cells. While at higher concentrations, the AGP-discharge effect overcomes the stimulation in synthesis.