Distribution of mast cells in human heart auricles and correlation with tissue histamine.

The mast cell density, fixation and staining properties, as well as tissue histamine, were studied in the human heart right auricles of 28 patients with mild atrial or ventricular septal defect (ASD or VSD respectively). We have found that different modes of fixation did not change significantly the mast cell appearance and number as stained with pinacyanol erythrosinate. The mast cell density was 21294 +/- 2775 cells per mm3 tissue and the mean histamine content of the auricle was 900.7 +/- 63.9 ng/g wet tissue weight. A significant positive correlation was observed between mast cell counts and histamine content (r = 0.79, p = 0.001). Furthermore, our data suggest the existence of a non-mast cell pool of cardiac histamine in man.