Isolation of histamine-containing cells from rat gastric mucosa: biochemical and morphologic differences from mast...

Enriched preparations of intact histamine-containing cells were obtained from rat stomach by enzymatic digestion and density-gradient separation techniques. The distribution of histamine in the various density-gradient fractions was highly correlated with that for both histidine decarboxylase and DOPA-decarboxylase. The fractions with the highest content of these substances (density about 1.040) contained 8%-12% of cells which by electron microscopy had the characteristic appearance of an enterochromaffinlike cell. The distribution of these cells in the density gradient appeared to correlate with the distribution of histamine. The gastric histamine cells differed from the rat peritoneal mast cells in that they possessed neither serotonin nor receptors for IgE and did not release histamine upon exposure to compound 48/80. The rat peritoneal mast cell, on the other hand, had high histamine (17 pg/cell) and serotonin (0.6 pg/cell) contents but lesser amounts of soluble histidine decarboxylase and little DOPA-decarboxylase activity. These studies provide further evidence that in rat gastric mucosal histamine is stored in a cell having the morphologic and biochemical characteristics of an endocrinelike cell and the ability to take up and decarboxylate biogenic amines.