Prostaglandin, slow-reacting substance, and histamine release from anaphylactic guinea-pig hearts, and its pharmacological modification.

Prostaglandins (Pgs), slow-reacting substance of anaphylaxis (SRS-A), and histamine were released from anaphylactic isolated perfused guinea pig hearts. Pgs were to the greatest part of the F2alpha-type. PgE2 was found in traces only. Neither PgA2, nor the metabolites 13,14-dihydro-15-keto-PgF2alpha and 13,14-dihydro-15-keto-PgE2 were detected in the perfusates. Isoproterenol reduced the PgF2alpha output significantly. This effect was increased by the addition of theophylline. Propranolol did not reverse the effect of isoproterenol, but in a high concentration (5 mug/ml) reduced the PgF2alpha output for its own. Indomethacin completely abolished the anaphylactic prostaglandin release. The histamine liberation was significantly decreased only by the combination of isoproterenol and theophylline, and also by a high concentration of propranolol (5 mug/ml). In contrast to the Pg release, the anaphylactic SRS-A and histamine liberation was not abolished by indomethacin, but rather increased. The results are discussed in view of the possible role of the released substances in the functional events of cardiac anaphylaxis.