Abstract
Histamine injected intra-arterially increases the permeability of the capillaries supplied by the artery. The rapid loss of protein from the plasma can be detected by comparing the blood draining from the part before and after the inj. The hematocrit reading and Hb conc. increased markedly while the protein conc. rose only slightly. A reaction similar to that produced by histamine is not seen in uninjured tissue in the usual types of shock.