Unknown

The reaction mixture consisted of 200 mL of washed rabbit platelet suspension, 25 mL of 3H-PAF (2.0 nM) with or without unlabelled PAF (2.0 mM) and 15 mL of sample or control solution. The final concentrations of sample in the reaction mixtures were 18.2, 9.1, 4.5, 1.8 and 0.9 mg/mL. The reaction mixture was incubated at room temperature for 1 h. The free and bound ligands were separated by filtration technique using Whatman GF/C glass fibre filters. The final concentration of DMSO (control) in the reaction mixture was fixed at 0.1% to avoid interference with the receptor binding studies. The reaction mixture with 0.1% DMSO in saline was used as a control and cedrol was used as a positive control. The radioactivity was measured by scintillation counting. The difference between total radioactivities of bound 3H-PAF in the absence and presence of excess unlabelled PAF is defined as specific binding of the radiolabelled ligand.