Significance of Histamine in Enhancement of Contractile Tension During the Atrial Anaphylaxis

Although it has been generally considered that histamine plays a principal role in the anaphylactic reaction, no hypothesis to explain it has been confirmed experimentally. This investigation was attempted to re-examine the significance of histamine in the anaphylactically induced dynamic responses. The results obtained are as follows : Histamine was released from the isolated atrial and ventricular muscle of sensitized guinea pigs in anaphylaxis. Numbers of mast cells in the ventricular muscle are incomparablly fewer than in the epi-and pericardium. Therefore histamine released during anaphylaxis would partially come from the muscle cell, that is to suppose that the cardiac muscle cell is sensitized by antigen. Metabolic inhibitors apparently depressed histamine release in atrial anaphylaxis. Monoiodoacetate (2.15 mM) inhibited histamine release almost completely, but provoked a dynamic response of the atrial anaphylaxis. Sodium arsenite (3.85 mM or more) inhibited completely the dynamic response of the atrial anaphylaxis, while histamine release was not completely reduced by arsenite. These results indicate that released histamine may not be responsible to dynamic responses in the atrial anaphylaxis