Voltage-gated sodium channels are responsible for the generation of action potentials in excitable cells. Recent electrophysiological characterization of twenty cockroach sodium channel variants in Xenopus oocytes revealed an impressive spectrum of differences in the level of sodium current expression, the voltage-dependence of activation and/or inactivation among variants. Some of the functional differences among the variants are the result of alternative splicing or RNA editing. The sodium channel gene in Drosophila melanogater, para, also utilizes alternative splicing and RNA editing extensively. However, the functional consequences of the alternative splicing and RNA editing of para transcripts remain largely unknown. In this study we isolated sixty four para full-length cDNA clones, expressed these variants in Xenopus oocytes and examined the gating properties using two-electrode voltage clamp. Our functional analysis of twenty nine Para variants (the rest of the variants are either non-functional or to be characterized) revealed that they exhibit a broad range of voltage-dependence of activation and inactivation. The voltage for half-maximal activation ranges from -10 to -40 mV. Variant Para-50 activates at -25 mV whereas the rest of the variants activate at more negative membrane potentials. The voltage for half-maximal inactivation ranges from -30 to -53 mV. Variant Para-13 inactivates at more positive membrane potential than other variants. The molecular bases of these differences in gating properties are currently under investigation.