ABSTRACT
A concentrative uptake mechanism for L-glutamate with the following characteristics has been identified in the abdominal nerve cord :
The uptake can be divided into Na+-sensitive and Na+-insensitive components.
The Na+-sensitive component showed the typical saturation kinetics of a carrier mediate process. It had a V of 15·9 × 10 −6μM/mg wet weight/min and a Km of 0·33 mm. Its magnitude was proportional to the first power of the Na+ concentration of the medium. The uptake was specific for L-di-carboxylic amino acids and was sensitive to the presence of metabolic inhibitors.
The Na+-insensitive component was linearly related to the glutamate concentration of the medium.
An isosmotic saline is described for use with the isolated intact abdominal nerve cord of P. americana.
