In view of the recent finding that
prostaglandin D2 is stereospecifically converted to 9 alpha, 11 beta-
prostaglandin F2, an isomer of
prostaglandin F2 alpha, a highly specific and sensitive radioimmunoassay for 9 alpha, 11 beta-
prostaglandin F2 was developed and applied to determine the content of this
prostaglandin in various rat tissues.
Antisera against 9 alpha, 11 beta-
prostaglandin F2 were raised in rabbits immunized with the
bovine serum albumin conjugate, and [3H]9 alpha, 11 beta-
prostaglandin F2 was enzymatically prepared from [3H]
prostaglandin D2. The assay detected 9 alpha, 11 beta-
prostaglandin F2 over the range of 20 pg to 1 ng, and the antiserum showed less than 0.04% cross-reaction with
prostaglandin F2 alpha,
prostaglandin F2 beta and 9 beta, 11 beta-
prostaglandin F2. To avoid
postmortem changes, tissues were frozen in liquid
nitrogen immediately after removal. The basal level of 9 alpha, 11 beta-
prostaglandin F2 was hardly detectable in various tissues of the rat examined, including spleen, lung, liver and brain; although it was found to be 0.31 +/- 0.06 ng/g wet weight in the small intestine. During convulsion induced by
pentylenetetrazole, enormous amounts of
prostaglandin D2 (ca. 180 ng/g wet weight) and
prostaglandin F2 alpha (ca. 70 ng/g) were produced in the brain; however, 9 alpha, 11 beta-
prostaglandin F2 was detected neither there nor in the blood. This result demonstrates that the conversion to 9 alpha, 11 beta-
prostaglandin F2 is a minor pathway, if one at all, of
prostaglandin D2 metabolism in the rat brain.