Abstract: | 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. |