Release of 5‐Hydroxytryptamine and Histamine from Rat Mast Cells¹

Abstract

Abstract The release of 5‐hydroxytryptamine (5‐HT) and histamine from rat peritoneal mast cells was studied. Major variations of amine content per cell were noted. Compound 48/80, n‐decylamine, polymyxin B, phospholipase A and distilled water released 5‐HT and histamine. The concentration‐response curve for 5‐HT to 48/80 was parallel to that of histamine. The number of histamine molecules released, considered as a ratio of the number of 48/80 molecules in the medium, ranged from 4 to over 40, whereas the corresponding ratio for 5‐HT ranged from less than 1 to approximately 2. The amine release by 48/80 was dependent upon pH and temperature and took place within 20 sec at 22° C. Certain enzyme inhibitors such as allicin (SH group inhibitor) and ninhydrin (NH 2 group inhibitor) blocked the amine release. Dinitrophenol inhibited the release only in glucose‐free medium. Sodium cyanide, 10 ‐4 M, and anoxia inhibited the release of neither amine. The results suggest that 5‐HT is released from mast cells by the same mechanism as is histamine. The data are in agreement with previous evidence from this laboratory favouring an enzymatic mechanism of release of histamine by polymer amine releasing agents.