The actions of retinal and retinoic acid on histamine release from rat peritoneal mast cells

Histamine release from rat peritoneal mast cells induced by anti-IgE was potentiated by the retinoids: retinoic acid 2-10 microM and retinal 1-5 microM. Retinal also produced a concentration-dependent increase in anti-IgE-stimulated 45Ca uptake by these mast cells. A similar potentiating action of both retinoids was observed on histamine release induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). For both anti-IgE- and TPA-induced histamine release, the potentiating effect of the two retinoids was only observed in the presence of extracellular calcium. In contrast, histamine release induced by compound 48/80 was inhibited by retinal 1-5 microM and by retinoic acid 10-50 microM and the inhibition was the same in the presence as in the absence of extracellular calcium 1 mM. Histamine release induced by calcium and the calcium ionophore A 23187 was inhibited by retinoid acid 2-10 microM and by retinal 10 microM. Inhibitions of compounds 48/80-induced histamine release by cromoglycate and by retinal were additive. It is concluded that while the actions of retinoids on rat peritoneal mast cells are consistent with the inhibition of protein kinase C, another action of these compounds, unrelated to this enzyme, may explain the data.