Comparison of the response of mast cells in guinea-pig cardiac atria and ventricles

A comparison was made between collagenase-dispersed guinea-pig atrial and ventricular tissues. Heparin containing cells were stained with alcian blue at pH 2.2, and counted by an automated technique (Technicon H6000). The cells were challenged with the specific antigen (ovalbumin), with antisera to guinea-pig IgG (non-subclass specific), IgG₁ and IgG₂, and the calcium ionophore A23187. Histamine release was measured by an automated spectrofluorometric technique, and leukotriene C₄ was measured by radioimmunoassay.All of the following parameters were higher in the atrial than in ventricular cells (mean ratio and SEM of atrial: ventricular mast cell parameters in parenthesis): 1) Histamine content/g wet tissues (3.32±0.71:1) (p<0.05), 2) Absolute mast cell number as a proportion of total cell count (3.75±1.64:1), 3) Histamine release induced by antigen (significant in one out of four experiments), anti-IgG (significant in three out of four experiments), anti-IgG₁ (significant in two out of four experiments), and anti-IgG₂ (higher but not statistically significant).Ionophore A23187 gave an inconsistent histamine release pattern: significantly higher release from atria in five treatments (different concentrations in different experiments), and higher ventricular release in three.Significantly more leukotriene C₄ was released by antigen and the ionophore A23187 (mean of 3–5 treatments), but not with anti-IgG.