Vincristine disturbs spontaneous firing of the afferent nerve fibre in ampullary electroreceptor organs

Ampullary electroreceptor organs of the catfish were apically exposed to 0.3 mM vincristine in order to investigate the part played by the microtubular system in stimulus transduction. The main effects were repetitive firing of the afferent fibre, a reduction of the mean spontaneous activity and a reduction of the spike amplitude two to four days after exposure to vincristine. The mean sensitivity was less susceptible to vincristine than the spontaneous activity. Since the shape of the frequency curves remained unchanged and similar effects as described above were also observed after denervation, we conclude that vincristine most likely does not affect electroreceptor cell functioning, but causes degeneration of the afferent fibre.