PROSTAGLANDINS RELEASED FROM THE ISOLATED PERFUSED ARTERIAL SEGMENT AND VASOCONTRACTILE RESPONSE: INFLUENCE OF PLASMA CONSTITUENTS AND PLATELETS

In the present study, relationship between each level of PGE, TX B2 and 6-keto-PGF1α in the effluent perfusate and vasocontractile response to noradrenaline (NA-R) was examined using the isolated perfused arterial segment of a rabbit ear. The following results were obtained. 1. NA-R was significantly augmented under the conditions infusing either platelet poor plasma (PPP) or platelet rich plasma (PRP), when compared with the control one during perfusion of modified normal Krebs solution (N-R) alone. 2. During PPP infusion, PGE level alone and during PRP infusion, both PGE and TX B2 levels showed significant increment in comparison with the each control ones during perfusion of N-R, respectively. 6-keto-PGF1α level was significantly altered under the conditions infusing neither PPP nor PRP. 3. There was the positively significant correlation between ΔNA-R and Δ (TX B2/PGE ratio), which represent the difference between the control value during perfusion of N-R and the one during infusion of either PPP or PRP, respectively. From the results obtained, it seems possible to draw the conclusion that the augmen-tation in NA-R induced by PPP or PRP relates, at least in part, to the secondary alteration of PGE and prostanoids metabolism in the arterial preparation.