Metabolism of prostaglandin F1α in the pulmonary circulation

³H_5,6-Prostaglandin F_1α 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 than PGF_1α itself. The pulmonary venous effluent contains the same metabolite along with some unmetabolized PGF_1α. 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 PGF_1α. Na0H has no effect on the metabolite, a finding that rules out the presence of a β-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.