Influence of the specific antagonist of PAF-acether, BN 52021, and of Ginkgo extract on the rejection of murine tail skin allografts and the PAF-acether mortality in mice in particular consideration of the role of TXB2.

An oral application of 2 x 10 mg/kg daily of the PAF antagonist, BN 52021, significantly prolonged the distal allograft survival in the murine tail skin model of cell-mediated allograft rejection. BN 52021 diminished the TXB2 content in the skin at and near to the transplantation site by two thirds whereas PAF-acether significantly enhanced the TXB2 content in murine tail skin. Similar to the tail skin BN 52021 also reduced by more than 70% the TXB2 release from human granulocytes stimulated by calcium ionophore A 23187. The PAF-acether mortality (LD75) in NMRI mice was decreased to 20% by BN 52021 with a lower dose than by BN 52020. Comparing Ginkgo total extract in doses which significantly diminished the 75% mortality by PAF-acether in mice with BN 52021 and BN 52020 in doses that produced the same inhibitory effect, a potentiated effect of Ginkgo extract resulted with respect to the share of BN 52021 and BN 52020 in Ginkgo extract.