Figure 9. Attenuation of the cardiopulmonary afferent-evoked activation of an NTS neurone by ionophoretically applied AP-5.

Activation of cardiopulmonary afferents by intra-atrial administration of phenylbiguanide (PBG, 12 μg kg⁻¹, 20 μl) at the solid horizontal lines evokes a burst of activity (31 spikes) in an NTS neurone (left panel). This excitatory response is reduced to 12 spikes when the same stimulus is given during ionophoretic application of the selective NMDA receptor antagonist AP-5 (120 nA; middle panel) and recovers to 26 spikes 5 min after removal of the AP-5 (right panel). From the top, traces show arterial blood pressure (BP; mmHg), a continuous rate histogram of neuronal activity (spikes bin⁻¹) and the raw recording of neuronal activity (cell, μV).