Effects of Intravenous Administration of Slow-Reacting Substance of Anaphylaxis, Histamine, Bradykinin, and Prostaglandin F2α on Pulmonary Mechanics in the Guinea Pig

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Abstract
The effects of intravenous administration of a purified preparation of slow-reacting substance of anaphylaxis (SRS-A), histamine, bradykinin, and prostaglandin F2α (PGF2α) on the mechanics of respiration were assessed in the unanesthetized guinea pig. Geometrically increasing doses of SRS-A resulted in graded decreases in average pulmonary compliance, with only modest increases in average pulmonary resistance. A dose with apparent maximal effects. 3,000 U/kg, resulted in a decrease of 49±7% of compliance below control values, with an increase in resistance of 24±8% above control. Intravenous administration of geometrically increasing amounts of histamine, bradykinin, and prostaglandin F2α also resulted in decreased compliance; but in each case this was accompanied by a marked increase in respiratory resistance. A decrease of compliance of approximately 50%, induced by intravenous histamine, bradykinin, or PGF2α, was accompanied by an increase of 60-140% in resistance. Thus, intravenously administered SRS-A alters pulmonary mechanics with a more peripheral effect than any of the other agents tested.