PRESENCE OF SPECIFIC PLATELET-ACTIVATING-FACTOR BINDING-SITES IN NEUROBLASTOMA N1E-115 CELLS

In this study we reported evidence for the existence of specific bindi ng sites for platelet-activating factor (PAF) in neuroblastoma N1E-115 cells. The specific [H-3]PAF binding reached a steady state level wit hin 60 min at 25 degrees C. Scatchard analysis of the specific [H-3]PA F binding revealed the presence of two apparent populations of binding sites. The high-affinity binding site possessed a K-d1 of 2.5+/-0.6 p M and B-max1 = 57.3+/-20.0 fmol/mg protein. The low-affinity binding s ite possessed a K-d2 = 3.2+/-1.0 nM and B-max2 = 4.4+/-2.1 pmol/mg pro tein, Furthermore, the total [H-3]PAF binding was partially displaced by unlabelled PAF, PAF antagonists BN 52021 and BN 50730 in a dose-dep endent manner. This study confirms the presence of specific PAF recept ors in neuronal cells.