Ac. Mork et al., CHLORIDE SECRETION IN THE SUBMANDIBULAR-GLAND OF ADULT AND EARLY POSTNATAL RATS STUDIED BY X-RAY-MICROANALYSIS, HISTOCHEM C, 105(4), 1996, pp. 297-303
Submandibular acinar cells of 1-day-old, 7-day-old, and adult rats wer
e analyzed with X-ray microanalysis after stimulation with carbachol f
or different time periods (2-7 min). In unstimulated animals, marked d
ifferences in elemental content between compartments could be observed
: secretory granules had a higher Ca and lower P and K content than ot
her cell compartments. Comparison between different age groups showed
significant differences for Ca, which increased with age in all compar
tments; Mg increased with age in the secretory granules and the apical
cytoplasm. Only the glands from adult animals showed a significant ef
fect of cholinergic stimulation: a transient decrease in Cl and K. The
Cl concentration in the secretory granules decreased to 60% of the co
ntrol value, which suggests that the granules release Cl upon stimulat
ion. In young animals, no or little change in elemental distribution w
as observed after stimulation. This may indicate that Cl- secretion me
chanisms are much less prominent in young animals. The ultra structure
of submandibular secretory granules depends on the preparation method
: condensed and electron-dense in freeze-substituted unfixed tissue, d
econdensed and more translucent in aldehyde-fixed tissue. This may ind
icate that the granules can transport water, and swell during the proc
ess of aldehyde fixation.