EFFECTS OF TETRANDRINE, FURA 2-AM, AND BAY-K-8644 ON PLATELET-ACTIVATING-FACTOR RELEASE FROM RAT PERITONEAL-MACROPHAGES STIMULATED BY LIPOPOLYSACCHARIDES

AIM: To study the relationship between the calcium and the release of platelet-activating factor (PAF) from rat peritoneal macrophages (PMO) by lipopolysaccharides (LPS). The effects of tetrandrine (Tet), Fura 2-AM, and Bay k 8644 on the PAF release from rat PMO was investigated by the bio-assay of PAF. RESULTS: LPS stimulated PMO to release PAF, w ithout increasing intracellular Ca2+ of PMO, Tet at 0.1, 1.0, 10, 100 mu mol . L(-1) and Fura 2-AM at 0.01, 0.1, 1.0, 10 mu mol . L(-1) coul d dose-dependently decrease the release of PAF (9.8 +/- 1.2, 6.5 +/- 1 .6, 4.7 +/- 0.8, 3.4 +/- 0.4 mu g . L(-1) and 9.2 +/- 1.7, 5.2 +/- 1.3 , 3.7 +/- 0.4, 3.2 +/- 0.3 mu g . L(-1), respectively, no drugs 11.8 /- 1.2 mu g . L(-1)), Bay k 8644 at 1.0, 5.0, 10 mu mol . L(-1) could dose-dependently increase the release of PAF (13.2 +/- 1.7, 16.2 +/- 1 .4, 17.6 +/- 1.5 mu g . L(-1)), and the effects of Tet and Fura 2-AM w ere completely or partly reversed by Bay k 8644 at 5.0 mu mol . L(-1). CONCLUSION: Although LPS did not increase intracellular Ca2+ of PMO, intracellular Ca2+ was necessary for PAF release from rat PMO stimulat ed by LPS.