Inhibition of GABA uptake potentiates the effects of exogenous GABA on locust skeletal muscle

Insect skeletal muscle is relatively insensitive to applied GABA, responses are elicited only when relatively high concentrations of GABA are used (greater than 10(-6) M). Pretreatment of the muscle with the GABA uptake inhibitors nipecotic acid, beta-aminobutyric acid or beta-alanine increases the sensitivity of the muscle to GABA by as much as 1000-fold. The evidence suggests the existence of a GABA uptake mechanism in the insect neuromuscular system which could reside in glial cells.