Effect of oral administration of arachidonic acid on prostaglandin and zinc metabolism in plasma and small intestine of the rat.

The effect of different doses of arachidonic acid (AA) on the intestinal zinc transport rate and on the plasma and intestinal PGE2, PGF2 alpha and 6-keto-PGF1 alpha levels in rats were measured to determine whether the metabolism of AA is involved in the zinc transport mechanism. Twenty-four rats were divided into 4 groups of 6 rats. Each rat received either 1.0 ml of distilled water, 0.5 mg, 1.0 mg or 1.5 mg/ml of AA intraduodenally at 24 and 4 hours before sacrifice. One hour before sacrifice, each rat also received 10 micrograms of 65Zn intraduodenally. The zinc transport rate decreased in comparison to controls when 0.5 mg of AA was given to the rats, but increased when 1.0 mg or 1.5 mg of AA was given. The levels of PGE2, PGF2 alpha and 6-keto-PGF1 alpha (PGI2 metabolite) in the intestinal mucosa all decreased in proportion to the amount of AA given. However, in the plasma, only PGF2 alpha levels decreased while PGE2 and 6-keto-PGF1 alpha levels showed no change compared to controls. When rats were given 1.5 mg of AA without oral administration of 65Zn, plasma PGE2 levels increased while PGF2 alpha levels decreased. The results suggest that AA metabolism influences the zinc transport mechanism by modulating the relative levels of PGE2, PGF2 alpha and PGI2 in plasma and small intestine.