Effects of forskolin alone and in combination with isoproterenol on antigen-induced histamine release from guinea-pig minced lung.

Forskolin inhibited antigen-induced release of histamine and leukotrienes from minced guinea-pig lung. The apparent potency of forskolin was similar for the two measured responses. Combination of forskolin with isoproterenol resulted in an additive inhibition of histamine release. The results support the contention that increases in cyclic AMP can inhibit antigen-induced histamine release, but a two-site model for forskolin does not appear to be operative in this system.