Effects of prostaglandins E1, E2, F2 alpha and arachidonic acid on aryl hydrocarbon hydroxylase activity of intestinal and hepatic microsomes from male rats.

The in vitro effects of prostaglandins E1, E2, F2 alpha and arachidonic acid on microsomal aryl hydrocarbon hydroxylase (AHH) activity from rat liver and intestinal mucosa were examined. PGE1 and PGE2 stimulated AHH activity of intestinal microsomes, while both prostaglandins had an inhibitory effect on AHH activity of liver microsomes. PGF2 alpha had little effect on AHH activity of intestinal and hepatic microsomes. Arachidonic acid exerted strongly inhibitory effects on AHH activity of both intestine and liver, with the greatest inhibition being exerted against intestinal AHH. Kinetic studies demonstrated that the inhibition of hepatic AHH activity by PGE1 at concentrations of 0.10 mM or less was non-competitive.