AUTHOR=Krey Rebecca A., Goodreau Adam M., Arnold Thomas B., Del Negro Christopher A. TITLE=Outward Currents Contributing to Inspiratory Burst Termination in preBötzinger Complex Neurons of Neonatal Mice Studied in Vitro JOURNAL=Frontiers in Neural Circuits VOLUME=4 YEAR=2010 URL=https://www.frontiersin.org/journals/neural-circuits/articles/10.3389/fncir.2010.00124 DOI=10.3389/fncir.2010.00124 ISSN=1662-5110 ABSTRACT=

We studied preBötzinger Complex (preBötC) inspiratory interneurons to determine the cellular mechanisms that influence burst termination in a mammalian central pattern generator. Neonatal mouse slice preparations that retain preBötC neurons generate respiratory motor rhythms in vitro. Inspiratory-related bursts rely on inward currents that flux Na⁺, thus outward currents coupled to Na⁺ accumulation are logical candidates for assisting in, or causing, burst termination. We examined Na⁺/K⁺ ATPase electrogenic pump current (I_pump), Na⁺-dependent K⁺ current (I_K–Na), and ATP-dependent K⁺ current (I_K–ATP). The pharmacological blockade of I_pump, I_K–Na, or I_K–ATP caused pathological depolarization akin to a burst that cannot terminate, which impeded respiratory rhythm generation and reversibly stopped motor output. By simulating inspiratory bursts with current-step commands in synaptically isolated preBötC neurons, we determined that each current generates approximately 3–8 mV of transient post-burst hyperpolarization that decays in 50–1600 ms. I_pump, I_K–Na, and – to a lesser extent – I_K–ATP contribute to terminating inspiratory bursts in the context of respiratory rhythm generation by responding to activity dependent cues such as Na⁺ accumulation.