The influences of andrenotropic drugs and noradrenaline on the histamine release in cardiac anaphylaxis in vitro.

1. The regional distribution (auricles, ventricles and septum) of histamine and its release during anaphylaxis were studied in isolated perfused guinea-pig hearts.2. The highest value of histamine content was found in the right auricle, the lowest in the left ventricle and septum, both in normal hearts, and in the hearts subjected to anaphylaxis.3. The fraction of the total histamine released in the course of 24 min by antigen was 50%. The fraction released from the different regions of the heart was similar. No evidence was found for release of 5-hydroxytryptamine.4. A relation was found between the distribution of mast cells and the tissue concentration of histamine. The highest number of mast cells per unit area was found in the right auricle; the lowest in the left ventricle.5. The histamine release by antigen was reduced by previous treatment with (+)-tubocurarine; the histamine release by (+)-tubocurarine was depressed by previous challenge of the heart with antigen.6. Reserpine reduces histamine release. Perfusion of reserpine-treated hearts with noradrenaline partially restored histamine release.7. beta-Adrenergic blocking agents (dichloroisoproterenol and pronethalol) reduced histamine release.8. The drugs tested did not modify the tissue concentration of histamine.9. The possibility of a modulating activity of catecholamines on histamine release in cardiac anaphylaxis is discussed.