The influence of the convulsant pentylenetetrazol on Ca2+-selective microelectrodes (neutral carrier ETH 1001).

Interference of the epileptogenic drug pentylenetetrazol (PTZ) on the Ca2+-selective microelectrode based on the neutral carrier ETH 1001 is described. It is suggested that tetraphenylborate, a component of the Ca2+-selective membrane, is responsible for this interference. Though the sensitivity of the Ca2+-selective microelectrode to PTZ is low, the error in measurements of the free Ca2+ concentration in biological preparations treated with PTZ has to be considered, since pathological changes in the extracellular Ca2+ concentration also produce relatively small changes in the relative electrode potential.