Abstract
1. When a solution of histamine was applied to the skin of rats and mice, and India ink injected intravenously, the endothelial cells of the small capillaries phagocytized the carbon particles in the treated area. No phagocytosis was observed beyond this area.
2. The induced phagocytic function of the endothelial cells endured for fifteen minutes. Phagocytosis could be reactivated in the same site by repeated application of histamine, thus demonstrating the reversibility of the cellular alteration.
3. It was found that the phagocytic activity is diminished by small concentrations of antihistaminic substance and inhibited by higher concentrations (1 per cent).
4. The endothelial cells of the small capillaries in the skin traumatized by burning or freezing show similar phagocytosis. Diphenhydramine diminished the phagocytic activity in the case of mechanical injury.
5. The possible mechanism of action of histamine and the antihistaminic substances is discussed.
Footnotes
- Received May 11, 1951.
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