Effect of DMSO on electrode during electrophoresis?: DMSO will not have any effect on electrodes of your electrophoresis unit because it is bipolar organic solvent which readily dissolves range of organic compounds including water. So once you run your samples containing DMSO, wash your electrophoresis apparatus with water. It should be perfectly fine.
in addition to the answer from Sudha electrodes in good electrophoresis apparatus is made of platinum which is chemically inert under almost all conditions