Release of prostaglandins evoked by neurohormonal stimuli in the isolated spleen of rabbit.

In the isolated spleen of rabbit perfused with Tyrode solution, sympathetic nerve stimulation (NS) and administration of either noradrenaline (NA), 50--75 ng, or bradykinin (BK), 50 ng, released a material into the venous effluent that caused contraction of rat stomach strip (RSS), rat colon (RC), chick rectum (CR) and bovine coronary artery (BCA). The musculotropic activity of the material released from the spleen was not diminished when it was allowed to stand at either 37 degrees C or at room temperature. The release of this musculotropic material evoked by neurohormonla stimuli was abolished during the infusion of the prostaglandin (PG) synthesis inhibitor, indomethacin, 1 microgram/ml. Application of authentic PGE2 directly on the assay organs caused contraction, whereas PGI2 contracted RSS, RC, and CR but relaxed BCA. In the spleen labeled with [14C]AA, NS, NA or BK released radiolabeled products having the chromatographic characteristics of PGE2 and, to a lesser extent, of PGF2 alpha. Indomethacin abolished the release of these radiolabeled products from the spleen. These observations taken together with the musculotropic characteristics of the material in the venous effluent, suggest that PGE2 is the major product of cyclo-oxygenase relased by NS, NA and by BK from the isolated perfused spleen of rabbit.