Using the granuloma pouch technique of SELYE, effect of modification in local histamine on the inflammatory tissue reactions was examined in rats. The increase in the weight of pouch wall and histological inflammatory changes were distinctly inhibited in either case of histamine depletion
by sinomenine and of desensitization to histamine by repeated injections of histamine. In rats injected with aminoguanidine, the skin and local histamine contents increased in similar degree as those in rats receiving histamine injection, but the inflammatory tissue reactions were severer than in the control. The total histamine of the pouch wall during inflammation reached the maximum four days after the injection of croton oil and decreased thereaftcr. The prcliferative processes indicating the recovery of injured tissues in later stages of the inflammation were the most vigorous in rats treated with histamine and this was in contrast to the extreme weakness of this tendency in animals in which the local histamine had been depleted. These observations not only suggests the fairly close relationship of histamine to carly reaction of inflammation but also indicates the role of histamine in its recovery processes.</p
