Contribution of post-secretory mechanisms to the observed pattern of histamine and 5-hydroxytryptamine secretion from peritoneal rat mast cells in response to compound 48/80

Compound 48/80 induces a greater percentage release of histamine than 5-HT from purified peritoneal rat mast cells such that the log-concentration effect curves diverge. Mast cells were shown to remove histamine and 5-HT applied exogenously, although uptake of 5-HT was in preference to that of histamine. At concentrations of clomipramine and fluoxetine that were shown to inhibit 5-HT uptake, the net percentage release of 5-HT increased in a corresponding manner. Likewise, pargyline and nialamide, which inhibit monoamine oxidase, potentiated the release of 5-HT, although they were without effect upon 5-HT uptake. Observed differences in the pattern of histamine and 5-HT secretion are proposed to be the result of post-secretory events involving amine reuptake and metabolism rather than a reflection of differential release mechanisms.