A SIMPLE METHOD TO IMPROVE THE RELIABILITY OF IONTOPHORETIC ADMINISTRATION OF TRACER SUBSTANCES

Microiontophoresis is a widely used technique for depositing tracer ma terials into the central nervous system for neuroanatomical experiment s. However, the reliability of iontophoretic injection is often less t han optimal. Coating the lumen of glass micropipettes with silicone to reduce surface tension reduced the incidence of failure for iontophor etic deposition of wheat germ agglutinin-horseradish peroxidase (WGA-H RP) from 40% to zero. Similar results were observed with other tracer substances. Siliconizing the internal surface of glass micropipettes c an significantly improve the reliability of iontophoretic deposition.