Arachidonic acid in guinea pig uterus and plasma.

1. The concentration of unesterified arachidonic acid was low in relation to tissue-esterified arachidonic acid. 2. Intracellular esters contain high concentrations of arachidonic acid, and 75% of this ester pool lies in two compounds, phosphatidyl choline and phosphatidyl ethanolamine. 3. The distribution of arachidonic acid among plasma lipids contrasted with the uterine distribution, with microgram/ml quantities in each of the major lipid classes.