Activation of non‐NMDA receptors participates in the reduction of inspiratory neural network complexity during gasping in arterially‐perfused adult rat

We have previously demonstrated that blockade of NMDA and/or non‐NMDA receptors not only alters the timing and patterning of basal inspiratory motor output, but also modifies spectral dynamics during both eupnea and gasping. The changes observed in basal inspiratory motor discharge are accompanied by an increase in inspiratory neural network complexity, as quantified by approximate entropy (ApEn) analyses; however, changes in network complexity during gasping under these conditions remain to be identified. Therefore, we computed the ApEn of gasps recorded under control conditions and during blockade of NMDA and non‐NMDA receptors in an arterially‐perfused adult rat preparation. Individual and simultaneous blockade of NMDA and non‐NMDA receptors was accomplished by perfusion with AP5 (40–50 μM, n=6), NBQX (2–5 μM, n=5), KYN (1.5 mM, n=3), and an AP5/NBQX cocktail (20 μM/5 μM, n=3). During gasping, in the absence of antagonist (control) and during perfusion with AP5, ApEn was reduced by ~16.2% (as compared to baseline values). In contrast, ApEn was reduced by only ~8.4% during gasping during perfusion with NBQX, KYN, or AP5/NBQX. These data demonstrate that NMDA receptor activation is not required for the reduction in ApEn observed during gasping, but non‐NMDA receptor activation appears to account for ~50% of the decrease seen. We suggest that activation of non‐NMDA receptors participates in reducing inspiratory network complexity during gasping. Supported by NS045321 and NS049310