INHIBITION OF RELEASE OF SLOW-REACTING SUBSTANCE BY ARSENIC

The effects of arsenic, in the form of Fowler's solution, on sensitized guinea-pigs have been studied in an attempt to explain the previously reported beneficial effects of the metal in the treatment of patients with asthma. Arsenic was found to prevent the release of SRS-A and histamine in isolated perfused lungs in the presence of specific antigen. It also blocked the contraction of isolated, sensitized ileum in contact with antigen. Arsenic did not markedly inhibit the action of SRS-A, histamine or acetylcholine on isolated ileum. Some animals treated with arsenic survived anaphylactic shock whereas all untreated animals died. It was concluded that arsenic is effective in the treatment of asthmatic patients because the release of histamine and SRS-A in the lungs is blocked. Arsenic does not appear to block the union of antigen with antibody and must inhibit a later step in the reaction. The possible mechanism of action is discussed. © 1969.