SYNERGISTIC EFFECT OF ELECTRIC PULSES AND BLEOMYCIN ON CULTURED RABBIT SUBCONJUNCTIVAL FIBROBLASTS

. Background: The combined effect of electric pulses (EP) and antiprol iferative agents on the proliferation of rabbit Tenon's capsule fibrob lasts was investigated. . Methods: Rabbit Tenon's capsule fibroblasts were cultured. Some of these cells were exposed to various intensities of EP alone (500-2500 V/cm). Other cells were then exposed for 30 min to an antiproliferative agent: bleomycin (BLM; 0.0005-50 mu mol/l), m itomycin C (MMC; 0.0005-50 mu mol/l), 5-fluorouracil (5-FU; 0.05-5000 mu mol/l), or streptomycin (SM; 0.0005-50 mu mol/l) with or without EP (2000 V/cm, 99 mu s, eight pulses). Cell proliferation was assessed b y cell counting on day 3 and by a H-3-thymidine uptake assay. DNA frag mentation was as sessed by flow-cytometric analysis and agarose gel el ectrophoresis. . Results: A significant reduction in the cell number w as observed only at 2500 V/cm (P<0.05). BLM, MMC and 5-FU treatment in hibited cell proliferation in a dose-dependent manner either with or w ithout EP (ID50: BLM alone, 0.029 mu mol/l; BLM and EP, 0.00022 mu mol /l; MMC alone, 41.6 mu mol/l; MMC and EP, 27.5 mu mol/l; 5-FU alone, 1 045 mu mol/l; 5-FU and EP, 690.2 mu mol/l; P<0.05). EP treatment induc ed an inhibitory effect of BLM on cell proliferation which was 100 tim es more prominent than BLM alone (0.0005 mu mol/l of BLM alone 103.4 /- 4.4%, 0.0005 mu mol/l of BLM and EP 26.0 +/- 4.4%; P = 0.021). BLM treatment with EP also augmented the apoptotic-like DNA fragmentation in both a flow-cytometric DNA histogram and agarose gel electrophoresi s. . Conclusion: EP treatment enhanced the inhibitory effect of BLM on the cell proliferation of Tenon's capsule fibroblasts of rabbits. The combination of electric pulses and antiproliferative drug treatments may therefore reduce the necessary dose of antiproliferative agents in filtering surgery.