Effects of D-tubocurarine on the ampullar receptors of the frog.

Abstract

In order to better define the action of D-Tubo-curarine on the ampullar receptors in frog vestibular apparatus the drug was applied to isolated open semicircular canals as well as to the entire undissected labyrinths. Curare was able to depress or abolish, according to the doses employed (50-200 μg/ml), both the resting discharge of the ampullar receptors and their responses to mechanical or electrical stimulations only when it was administered to the isolated open semicircular canals; contrariwise almost no effect was detectable when curare was administered to undissected preparations. The action of this drug develops earlier on the sensory units responsible for spikes of higher amplitude than on those responsible for medium and lower spikes: this effect may be interpreted as an enhancement of the threshold extended to the whole receptor population comprising the crista ampullaris. Curare blockade of the mechanical responsiveness in ampullar receptors is fully reversible in about 15 min after withdrawal ...