Influence of organochlorine pesticides on transmembrane potential, oxidative activity, and ATP-induced calcium release in cultured bovine oviductal cells.

The present study investigated the effects of the pesticides DDT, MXC, and gammaHCH on transmembrane potential, oxidative activity, cytotoxicity and ATP-induced intracellular Ca2+ release in cultured bovine oviductal cells. Transmembrane potential, oxidative activity, and cytotoxicity were assessed using the fluorescent dyes bis-oxonol, dihydrorhodamine 123, and propidium iodide (PI), respectively, and measured spectrofluorometrically in a microplate reader. The cultured cells were loaded with Ca2+-sensitive fluorochrome fura-2-AM, and cytosolic free calcium ([Ca2+]i) was monitored by a microscope image analysis system. A dose-dependent increase in depolarization and changes of oxidative activity were observed over a concentration range of 8 to 128 microM DDT and MXC compared to nonexposed controls. At a concentration of 16 microM DDT or MXC, the oxidative activity and depolarization of cells were significantly enhanced compared to controls, but most of the cells were intact as indicated by the fact that PI-staining was not significantly increased. Trypan-blue staining indicated that the viability of oviductal cells decreased significantly when exposed to concentrations of 64 and 128 microM DDT or MXC. ATP-mediated enhancement of [Ca2+]i in cells was almost completely inhibited after incubation with 128 microM DDT for 3 h at 37 degrees C. This response was reduced to approximately 50% after incubation of the cells with MXC at 128 microM; lindane did not significantly interfere with the above physiologic parameters.