Further studies of the mechanism of counter irritation by turpentine.

The influence of counter irritation by turpentine (0.2 ml) on zymosan- and carrageenan-oedemas was investigated in the rat. Zymosan-oedema was inhibited by mepyramine and methysergide and by leucopenia. It was not modified by captopril and developed normally in kininogendeficient Brown Norway rats. Leucocytes and mast cell amines but not kinins are thus involved in zymosan-oedema. The last phase of this reaction was inhibited by counter irritation alone, but the odema was largely depressed by counter irritation in rats pretreated with mepyramine and methysergide. Carrageenan-oedema was increased by kininase inhibitors and inhibited by leucopenia in normal rats. This inflammatory reaction had a small developement and was not increased by kininase inhibitors in kininogen-deficient BN rats. Leucocytes and kinins participate in the developement of this inflammatory reaction in normal rats while kinins are lacking in deficient rats. Counter irritation depressed carrageenan-oedema in deficient Brown Norway rats and suppressed the potentiating effect of kininase inhibitors in normal rats. Carrageenan oedema was nearly abolished in turpentine-treated leucopenic rats. These results suggest that the anti-inflammatory effect of counter irritation by turpentine could depend on a reduction of leucocyte accumulation into zymosan-oedema and on a reduction of both kinin formation and of leucocyte accumulation into carrageenan-oedema. The significance of T-kininogen as acute phase reactant is discussed.