Conductance changes during bath application of beta-alanine and taurine in giant interneurons of the isolated lamprey spinal cord.

(1) Input conductances of giant interneurons in the isolated spinal cord of lampreys were measured with two separate intracellular electrodes. Bath applications of 0.4--3 mM beta-alanine and taurine produced large, reversible conductance increases which were Cl-dependent. (2) Strychnine at 1--2.5 microM might be a competitive antagonist of both amino acids, but had a stronger effect on taurine. Bicuculline and picrotoxin were weak antagonists of beta-alanine and taurine in some cells. (3) A few giant interneurons desensitized after repeated application of the amino acids, but most became more sensitive. Responses to the amino acids also increase at low temperatures in in Na-free fluid, suggesting effect of uptake mechanisms.