Stimulation by carrageenan of arachidonate 12-lipoxygenase activity in dog gingival tissue

At 4 h after injection of carrageenan into the gingiva, the 12-lipoxygenase activity of the gingival homogenate was markedly increased. Activity in the cytosol and microsomal fractions was markedly increased when assessed as the specific activity based on nmol/min/mg of protein, and in the cytosol fraction as the percentage distribution of total activity. The 12-lipoxygenase activity in the homogenate from carrageenan-treated gingiva was not affected by either EDTA or calcium ion, or a combination of the two. 12-lipoxygenase activity in both carrageenan-treated and untreated gingiva was inhibited dose-dependently by AA861, a striking difference from its effect on platelet 12-lipoxygenase. There was a marked increase of 12-lipoxygenase activity in experimentally inflamed gingiva compared to the non-inflamed gingiva.