Chemoreception of the lateral-line organ of an aquatic amphibian, Xenopus laevis.

Abstract

The lateral-line organ of Xenopus laevis was studied by recording responses from its afferent nerve fiber. The firing rate was registered with the aid of an electronic rate meter.1. The firing rate was remarkably increased by stimulation with KCl and NH4Cl.2. Sodium salts (except for Na-glutamate) suppressed both the spontaneous activity and responses to other cations. Na-glutamate did not show the suppressive effect at all.3. Salts of divalent cations, CaCl2, and MgCl2, increased the firing rate, in contrast to the results obtained with fish, where they suppressed the responses to monovalent cations.4. The discharge pattern from all the afferent fibers examined was quite uniform, so that the fibers could not be separated by response patterns into different groups.5. Neither tetrodotoxin nor Mn++ suppressed the responses to solutions of salts, including those of Ca++.6. Sucrose and quinine produced no remarkable effects, in contrast to the effects produced on the gustatory organs.7. Dihydrostreptomycin sulfate (SM) suppressed both mechano- and chemoreception.8. Along with serving as a mechanoreceptor, the lateral-line organ of Xenopus probably functions as an external chemosensory organ in detecting ions in the environment.