The relationship between functional vasodilatation in adipose tissue and prostaglandin

Abstract

1 . Earlier it had been found that during fat mobilization there was an increased blood flow in the adipose tissue and the tissue contained a vasodilator substance. 2 . Extract of an activated fat pad contained 3 to 25 times as much activity as the contralateral resting fat pad. 3 . The following findings suggest that the vasodilator substance is prostaglandin E₂: (a) It caused contractions of the guinea-pig ileum which were not reduced by mepyramine, but were reduced by atropine. (b) It caused a prolonged vasodilator response when injected close-arterially to the epigastric fat pad. (c) It was eluted from a silicic acid column by a solvent system which is known to elute prostaglandins of the E series but not those of the F series. (d) Its indices of discrimination were similar to those of prostaglandin E's when assayed on three different pharmacological preparations. (e) On thin-layer chromatography it behaved more like prostaglandin E₂ than E₁. 4 . Neither prostaglandin E₁ nor prostaglandin E₂ inhibited the release of free fatty acids from the rabbit epigastric fat pad by ACTH^1–24. 5 . It seems likely that prostaglandin E₂ is responsible for the vasodilatation accompanying fat mobilization from adipose tissue.