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 reexamine 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 incomp-arablly 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. It was presented by H. H. DALE and P. P. LAIDLAW 6) that the antigen-atibody union in the body causes liberation of histamine which participates in the contractile responses, the so called histamine theory7>. The theory has been supported by many workers 1)2)4)5)9)26) mostly from agreement in amounts of released histamine and its comparable biological activities or from similarity of pharmacodynamic action of hista-mine and of anaphylactic reaction. On the other hand, K NAKAMURA23) has made a versatile study on the mode of anaphylactic reaction and claimed the importance of acetylcholine instead of histamine because they *1 A part of this work was presented at the 17th regional meeting of the Seinan area of the Japanese Pharmacological Society in November 1964. *2ˆÀ " c OEõ'¥ 1964 HISTAMINE IN ATRIUM ANAPHYLAXIS 201 observed closer similarity in acetylcholine. Y. NAKAZAWA24) and K. GREEF11) reported the anaphylactic reaction in the atrial preparation of guinea pig, the increase of contractile force and beat rate. F. KIHARA15) have shown that various antihista minicagents did not inhibit atrial anaphylaxis, and he considered that released histamine might not be a substance principally responsible to the anaphylactic reaction in the atrium. The other paper from our laboratory also criticized the role of acetylcholine, noradrenaline and serotonin in atrial dynamic anaphylaxis16)25) Recentry, Y. NAKAZAWA and A. UEN027) reported that the configuration of intracellular action potential of a …