Differential effects of potassium channel blockers on the activity of the locomotor network in neonatal rat.

The role played by various K+ channels during locomotor activity was studied using an in vitro neonatal rat spinal cord preparation. Locomotor-like activity was elicited by bath-applying serotonin (5-HT) and N-methyl-d-l-aspartate (NMA). Four different K+ channel blockers were tested by adding them to the superfusing saline. Each of the K+ channel blockers elicited a characteristic motor pattern with specific temporal parameters. Cs+ and tetraethyl ammonium both decreased the motor period, but had opposite effects on the burst amplitude. Apamin increased both the motor period and the burst amplitude. A dose-response relationship was established for the K+ channel blockers. The blockers elicited an unstable rhythmic activity, contrary to what occurred under control conditions. We also found that due to the specific changes that they elicit, the various blockers produce selective changes in the burst ratio. These results suggest that the various K+ channels contribute differently to the generation of locomotor activity. Copyright 1999 Elsevier Science B.V.