Increased prostaglandin synthetase activity in inflamed tissues of the rabbit eye

Tissues from normal and inflamed rabbit eyes were examined for prostaglandin synthetase activity using homogenates and microsomal preparation. Ocular inflammation was induced with 10 microgram Shigella endotoxin injected into the vitreous body. Homogenates of iris-ciliary processes of normal and inflamed eyes synthesized 2.3 and 5.6 microgram respectively of prostaglandins per g wet weight of tissues from endogenous substrate. Intact tissues from normal and inflamed eyes produced similar amounts of prostaglandins (2.2 and 5.3 microgram/g wet wt. respectively). Microsomes obtained from inflamed tissues produced 565 ng of prostaglandins per mg of protein per 30 min compared with 190 ng synthetized by normal microsomes. The apparent Km for the substrate of prostaglandin synthetase from inflamed tissues compared with that from normal was found to be lower. It is suggested that prostaglandin synthetase activity in the ocular tissues is modified during Shigella endotoxin-induced inflammation.