metiamide and Poultry-Diseases

Pentobarbital-anesthetized and spontaneously breathing, bovine albumin (BA)-sensitized adult domestic fowl showed acute systemic anaphylaxis to IV injection of antigen (BA), which was characterized by arterial hypotension, central venous hypertension, and bradycardia. Large doses of pyrilamine maleate (/1-receptor antagonist) partially inhibited acute systemic anaphylaxis. On the other hand, metiamide (a specific H2-antagonist) and propranolol (beta-adrenergic antagonist) markedly enhanced the anaphylactic response. Terbutaline (beta 2-agonist), dimaprit (a highly selective H2-agonist), and compound FPL 55712 (a slow-reacting substance of anaphylaxis receptor antagonist) either significantly inhibited or reversed the anaphylactic response. Cimetidine (a newer H2-antagonist) enhanced only central venous pressor response to BA. This investigation appears to suggest a minor role of histamine and a major role of slow-reacting substance of anaphylaxis as chemical mediatiors of anaphylaxis. A protective role of beta 2-adrenergic and H2-histaminergic receptors seem to operate in immediate hypersensitivity reactions in adult domestic fowl.

Topics: Anaphylaxis; Animals; Blood Pressure; Carotid Arteries; Chickens; Chromones; Cimetidine; Dimaprit; Ethers; Heart Rate; Metiamide; Poultry Diseases; Propranolol; Pyrilamine; Receptors, Adrenergic; Receptors, Adrenergic, beta; Receptors, Histamine; Receptors, Histamine H2; Terbutaline; Thiourea