Effect of Phlorizin on the in Vitro Release of Histamine from Lung Tissue1

Histamine release was induced from sensitized guinea‐pig lung tissue by antigen, and from non‐sensitized rat lung tissue by compound 48/80. Phlorizin (10‐3M) had no apparent inhibitory effect on the histamine‐releasing reactions when elicited under nitrogen in the presence of 5.6 × 10‐3M glucose. When the glucose concentration was decreased to 7 × 10‐4M, phlorizin (10‐3M) inhibited histamine release under nitrogen in both reactions, to the same extent as did nitrogenation in the absence of glucose. Under nitrogen, the enhancing effect of glucose was progressively inhibited by increasing concentrations of phlorizin. In both reactions, its inhibitory effect decreased with rising glucose concentration. The results are interpreted to indicate that phlorizin inhibits histamine release mainly by inhibiting the transport of glucose.