Short-term potentiation of carotid chemoreflex: an NMDAR-dependent neural integrator

REPETITIVE stimulation of the carotid sinus nerve (CSN) elicits a short-ter m potentiation (STP) of the reflex response in respiratory motor output in mammals. The input-output transformation approximates a leaky integrator wi th a time constant of several seconds. Here, we showed that STP induced by CSN stimulation in rats was manifested in the reflex response in the amplit ude of rhythmic phrenic nerve activity as well as its duration. Moreover, p harmacological blockade of NMDA receptors (NMDAR) resulted in marked increa ses in the time constants of the equivalent neural integrator in both the S TP induction phase (by 10- to 20-fold) and recovery phase (by 1- to 5-fold) . Thus, NMDAR serves as a molecular switch that facilitates the integrative processing of CSN inputs by STP. NeuroReport 10:2261-2265 (C) 1999 Lippinc ott Williams & Wilkins.