Histamine in the Rabbit Skin

Abstract

Using the trypan blue test we have shown 1 that histamine injected intradermally in the very young rabbit does not cause a seepage into the injected area of the dye injected intravenously. This fact is consistent with an observation described by Feldberg and Kella-way 2 on the pharmacological effect of histamine on the cat. Very young cats are very resistant to the injection of histamine. In particular, the pressure in the pulmonary artery is only slightly altered by the intravenous injection of histamine in young cats, while the same dose injected into old cats may produce marked changes. By determining the histamine content of the lungs in cats varying in weights from 0.5 to 6 kg, they have shown a parallelism between the increasing amount of histamine in the lung tissue and the pharmacological effects produced by the drug when injected into the vein. This work was undertaken to ascertain whether a parallelism exists between the histamine content of the skin and the response to the trypan blue test.

Experimental. We have determined (41 rabbits) the amount of histamine in rabbit skin by employing the Barsoum and Gaddum method 3 as modified by Code. 4 A technic devised by us 5 was used to reduce the volume of the extract, when desirable. All figures regarding histamine refer to histamine dihydrochloride which was used in the assays. Simultaneously with the collection of the fragment of skin for extraction we determined the area of the skin slices. A rectangle of the skin surface was drawn against cellophane paper and the area measured over millimetered paper. Then the skin fragment was cut out with sharp scissors, the subcutaneous connective tissue carefully dissected and the rectangle of the skin weighed.