[An apparatus for ionophoretic application of some drugs with constant currents]

When agonists are ionophoretically applied to the neuromuscular junction using a short current pulse, the effect of stray capacity and the change of resistance of the ejecting micropipette on the output current has to be considered. The present paper describes an apparatus that was devised using OP-amplifiers so that the apparent stray capacity was remarkably reduced, and the amount of the output currents was in proportion to the input voltage of the short pulse even if the resistance of the micropipette changed markedly during the experiments.