Inhibition of glycine response by amiloride in rat spinal neurons.

The modulatory effect of amiloride on glycine-activated current (I(Gly)) was investigated in acutely dissociated rat spinal dorsal horn neurons using the whole-cell patch clamp technique. Amiloride inhibited I(Gly) reversibly in a concentration-dependent manner. It shifted the concentration-response relationship to the right without altering the maximum response and Hill coefficient of the I(Gly). Amiloride did not change the ion selectivity of glycine receptor either. In addition, Na(+) - or Ca(2+) -free extracellular solutions and intracellular application of amiloride did not alter the amiloride inhibition of I(Gly). These results indicate that amiloride directly inhibited the glycine receptor response by decreasing the affinity of glycine to its receptor.