Studies on the permeability of the glutamate receptor at the insect neuromuscular junction. 
Voltage clamp studies of the post-synaptic membrane of the locust neuromuscular junction have shown that the transmitter substance and L-glutamate cause an approximately equal increase in permeability to sodium and potassium.  The changes in reversal potential caused by altering external potassium, but not external sodium, were similar to those predicted by the Goldman equation.  The ionic channels of the glutamate receptor had a high permeability to a variety of inorganic and organic cations, indicating relatively non-selective channels of size approximately 0.6 x 0.4 nm.