In vivo metabolism of [1- 14C]arachidonic acid during different phases of granuloma development in the rat

Abstract

The metabolism of [1- 14C]arachidonic acid was studied in vivo during the development of carrageenin-induced granuloma in the rat. For this purpose a double-cannulated teflon cylinder was implanted into the dorsal subdermal tissue of rats, and the cannulae were exteriorised through the skin at the scruff of the neck. The “chamber” allowed the injection of substances and collection of exudate at different stages of granuloma development. When [1- 14C]arachidonate was injected into the chamber one hour before recovery of the exudate at periods up to 12 days after initiating the inflammation, hydroxy fatty acids and prostaglandin E 2 appeared to be the main products formed. Only very small amounts of thromboxane B 2 and 6-ketoprostaglandin F 1α were detectable. These in vivo results are in marked contradiction to observations of other workers with granuloma tissue in vitro. The present findings are discussed in relation to the postulated negative-feedback function of E-type prostaglandins and a possible role of hydroxy fatty acids in inflammation.