[Effect of pyridoxine on histamine liberation and degranulation of rat mast cells].

Pyridoxine, one of the B vitamins, has been shown to be useful in the treatment of childhood bronchial asthma by Collip et al. (1975). A double-blind study with 76 asthmatic children followed for five months indicated significant improvement in asthma following pyridoxine therapy (200 mg daily) and a reduction in dosage of bronchodilators and cortisone. Other reports have shown that nicotinamide, another B vitamin shows inhibitory activity in rat mast cell degranulation and histamine release (Bekier et al. 1974, Wiczolkowska and Maslinski, 1975, 1976). These results induced us to investigate if pyridoxine, like nicotinamide or disodium cromoglycate, exhibits pharmacological inhibitory activity in rat mast cell degranulation and histamine release induced by antigen or other non-immunological stimulants. We found that pyridoxine at concentrations of 10 (-3) M, or greater significantly inhibited rat mast cell degranulation and histamine release induced by phospholipase A, compound 48/80, antigen (egg albumin) or a mixture of dextran and phosphatidyl serine, respectively. In these experimental models, pyridoxine shows a pharmacological profile similar to nicotinamide and disodium cromoglycate, although weaker than the latter. In spite of this, the lack of toxicity of this vitamin at relatively high doses (1 or 1.5 g), the possibility that other mechanisms of action may be involved, such as the improvement in tryptophan metabolism reported by Collip following pyridoxine therapy, suggest that this vitamine merits additional research.