Diphasic disappearance of metachromasia in the rat gastric mucosal mast cells after a single injection of insulin

Two biochemically distinct populations of histaminocytes separated by isokinetic sedimentation of dispersed rat gastric cells

Two populations of histaminocytes, with different sedimentation rates (SR), were separated by a computer developed isokinetic gradient using dispersed rat gastric mucosal cells. Histamine content, histidine decarboxylase (HDC) activity and incorporation of radiolabelled histidine metabolites were used to assess the migration of specific cells throughout the gradients. One histaminocyte population, with cells of lower SR, contained high HDC activity and undetectable levels of histamine, whereas the other population, with cells of higher SR, contained lower HDC activity and high concentration of histamine. Both types of histaminocytes incorporated 3H-histidine metabolites. Electron microscopy showed that the fractions containing histaminocytes with lower SR had 3.5 times more endocrine ECL cells than the original population of dispersed fundic cells and lacked A and D cells, whereas the fractions with histaminocytes of higher SR were associated with a 2.7 times higher concentration of A and D cells and with a 7.7 times higher ratio of a variety of partial cells with a distinct mitochondrial morphology. These results are consistent with prior novel information regarding the separation of two populations of rat histaminocytes using different sedimentation techniques.

Separation and characteristics of two histaminocytes from rat gastric mucosa

To determine the properties of rat gastric cells involved in histamine metabolism (histaminocytes), fundic mucosa was enzymatically dispersed prior to separation by sedimentation methods. The distribution of histamine content, histidine decarboxylase (HDC) activity and incorporation of radioactive histidine metabolites were used to determine the characteristics of various populations of gastric cells. All activities measured, as well as most of the dispersed gastric cells, occurred in a narrow range of density between 1.083 and 1.091 g/ml. Velocity sedimentation showed that two populations of histaminocytes can be distinguished. One population has a higher sedimentation rate, suggesting a larger size, contains histamine, HDC activity and incorporates radioactive metabolites. Another population, in fractions with lower sedimentation rates, contains little histamine, has a higher HDC activity than the previous population and also incorporates radiolabelled histidine metabolites. For the first time, two populations of viable histaminocytes have been separated that differ in their biochemical properties.

The effects of zinc sulphate on vagal-induced mast cell changes and ulcers in the rat stomach

The effects of zinc sulphate pretreatment on the formation of gastric ulcers, changes in intragastric pressure and changes in the gastric mucosal mast cell count induced by electrical vagal stimulation were studied in anaesthetized rats. Vagal stimulation produced a high gastric glandular ulcer incidence and ulcer index, increased the intragastric pressure, and reduced the number of granulated mast cells in the gastric mucosa and submucosa. Pretreatment with zinc sulphate (22, 44 ot 88 mg/kg), injected i.p. 48 h beforehand, reversed the changes in these parameters in a dose-related manner. These observations suggest that the inhibitory effects of zinc sulphate on mucosal mast cell degranulation may account for its ability to antagonise vagal-induced gastric glandular ulceration. The mechanisms involved in the aetiology of this type of gastric ulcer are discussed in the light of these results.