INHIBITION OF 5 CALCIUM-CHANNEL BLOCKERS ON H2O2 RELEASE FROM MOUSE PERITONEAL-MACROPHAGES

After the peritoneal macrophages from mice were incubated with differe nt concentrations of calcium channel blockers for 3 h at 37-degrees-C , the macrophages were stimulated with opsonized zymosan for 1.5 h at 37-degrees-C. The releasedi H2O2 was measured by fluorescence assay. T he results showed that verapamil (Ver), nifedipine (Nif), nicardipine (Nic), nimodipine (Nim), and nitrendipine (Nit) reduced the H2O2 relea se significantly in a dose-dependent manner. The IC50 values (mumol . L-1) were 30, 50, 49, 63, and 92 for Nic, Nif, Nim, Nit, -and Ver, res pectively. There was slight inhibition of dihydropyridine (Bay k 8644) 10 mumol . L-1 on H2O2 release. When Bay k 8644 at above concentratio n combined with Ver, Nim, and Nit 25 mumol . L-1, respectively, the in hibitions of Ver, Nim, and Nit on H2O2 release were increased 32% - 40 %. Above results showed that on the inhibition of H2O2 release, the ef fects of dihydropyridines calcium channel blockers were greater than t hat of Ver, and the effects of Nic and Nif were greater than those of Nim and Nit. The acting sitei of Bay k 8644 at high concentration (10 mumol . L-1 and over) was probably different from that of typical calc ium channel blockers Nim, Nit, and Ver in macrophages.