Integration of controlled intracellular pressure microinjection, iontophoresis, and membrane potential measurement

A novel device for intracellular microinjection was designed to integrate c ontrolled pressure microinjection and electrical microinjection (iontophore sis) with membrane potential recording and a limited capacity for turgor me asurement. The validity of the device was verified by microinjection of a m ixture of the fluorescent probes, Texas Red sulfonyl chloride and 10 kDa-LY CH-dextran conjugate, into epidermal cells of variegated Coleus blumei leav es. Continuous monitoring of the fluorochrome movement by confocal laser sc anning microscopy evidenced that the novel device succeeded in differential microinjection of the fluorescent probes by pressure and iontophoresis, Th e multifunctionality of the microinjection system was further demonstrated by showing that both microinjection methods functioned in parallel with cel lular membrane potential measurements in Vicia faba stem tissue. Advantages and prospective applications of the integrated microinjection/membrane pot ential measurement system are briefly discussed.