Metabolism of prostaglandin f 1 alpha in the pulmonary circulation.

3-H5,6-Prostaglandin F1alpha is largely eliminated from the circulation during a single passage through the pulmonary vascular bed. Its elimination requires cellular uptake. The volume of distribution and the mean transit time of the radioactivity are greater than those of an intravascular marker, blue dextran. The lungs retain 25-30% of the radioactivity, most in the form of a metabolite less polar that PGF1alpha itself. The pulmonary venous effluent contains the same metabolite along with some unmetabolized PGF1alpha. The metabolite can be distinguished from prostaglandins of the A, B, D, E and F series. It is reduced on reaction with borohydride, but reduction does not yield PGF1alpha. NaOH has no effect on the metabolite, a finding that rules out the presence of a beta-hydroxy-ketone configuration of the ring structure. The chromatographic behavior of the metabolite and its reaction with borohydride are those expected of 9,11-hydroxy-15-ketoprostanoic acid.