Differential responses to NMDA receptor activation in nucleus of the solitary tract neurons: A putative role for transient potassium conductances

Previous reports from other brain areas have shown that transient outward potassium conductances may minimize the excitatory response of certain subclasses of neurons following NMDA receptor stimulation. Using medullary brain slices under whole cell current clamp configuration, this study examined the sensitivity of delayed excitation (DE) and post-inhibitory rebound (PIR) cells of the nucleus tractus solitarius (NTS) to NMDA receptor activation and the role of transient K+ conductances in these responses. PIR cells were tested with 10−6M NMDA agonist (dl-[tetrazol-5-yl] glycine).; DE cells were tested with NMDA agonist during bath applied 100μM 4-AP, which blocks only the I_D current.; Examination was made of the hyperpolarizing after-potential (HAP) of the action potential waveform during 100μM 4-AP.; This thesis provides evidence supporting a differential sensitivity to NMDA receptor activation between the two major cell types of the NTS. The potassium I_A current appears critical to DE cells in regulating the magnitude of the HAP and preventing excessive depolarization following NMDA receptor activation. (Abstract shortened by UMI.)...