Effect of Chlorpromazine, Mepyramine, Prenylamine and Reserpine on 5‐Hydroxytryptamine Content and Fine Structure of Rat Peritoneal Mast Cells Incubated in Vitro

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Abstract
The mechanism of action of the drugs tested in releasing 5‐hydroxytryptamine from mast cells in vitro was studied under different incubation conditions and by observing the morphological changes associated with the amine release. It was proposed that chlorpromazine, mepyramine and prenylamine release 5‐hydroxytryptamine by a mechanism of action not requiring energy because neither did the drugs exert their maximal effect at physiological pH values nor was the release blocked by pre‐incubation with sodium cyanide. The suggestion is supported by the morphological observations revealing destructive changes of the mast cells. The reserpine induced release of 5‐hydroxytryptamine from mast cells was small upon incubation in a phosphate buffer and was completely inhibited upon incubation in a physiological medium containing divalent cations sand glucose. The release was not decreased by lowering the temperature of the incubation medium from 37°C to 23°C which indicate a mechanism of action not requiring energy. On the other hand, reserpine had a maximal releasing effect around neutral pH values and the release was totally blocked by pre‐incubation with sodium cyanide suggesting a necessity for metabolically active cells. An energy requiring mechanism of action of reserpine was further supported by the observed morphological alterations which were much of the same nature as those induced by compound 48/80.