Secretory activity of the human bronchial mucous glands in vitro

Abstract

Incorporation and discharge of radioactive glucose and threonine by the mucous and serous cells of the human bronchial submucosal gland have been studied quantitatively using organ culture. Bronchi were mostly obtained from surgical specimens. Concentration of radioactive precursor in the culture medium did not influence the speed of its passage through the cell but changed grain density in the autoradiograph. A different method of quantification was needed for each cell type. Incorporation of glucose into the mucous and serous cells was essentially similar but a little slower in the serous. Threonine appears faster throughout a cell than does glucose but again rather more slowly in serous. In some mucous cells it appears only at base and apex, seeming to be within endoplasmic reticulum and not in the secretory granules. The secretory index (percentage of mucous cells secreting in 4 hours) was similar for all material from any one bronchus. Individual variation was seen and proved to be related to gland size, the higher the gland/wall ratio the higher the secretory index. This applied to the glands from chronic bronchitis, bronchiectasis, and cystic fibrosis. The relation between gland/wall ratio and secretory tubule and cell size has been estabilished.