Central chemoreceptor stimulation modulates Mayer wave‐related oscillatory activity of Retrotrapezoid nucleus/parafacial region (RTN‐pF) neurons

Abstract

A rostral extension of the ventral respiratory column, including the RTN-pF, contains neurons responsive to local perturbations of CO2/pH. Spike trains from RTN-pF neurons were recorded with multi-electrode arrays along with phrenic nerve activity in 5 decerebrate, vagotomized, neuromuscularly blocked, and artificially ventilated cats. While evaluating the responses of these neurons to chemoreceptor stimulation, we observed neurons with firing rate oscillations in the frequency range of Mayer waves (spontaneous oscillations of arterial pressure ~0.1 Hz in humans and cats, a frequency slower than respiration). Mayer wave-related oscillations (MWROs) occur in neuronal firing rates and are coupled to blood pressure and breathing (Morris et al. 2010). Of the 144 RTN-pF neurons tested with selective central chemoreceptor stimulation, we identified neurons with altered MWRO activity (evoked (n=21), enhanced (n=38), reduced (n=37)) while others were unaffected (no change (n=12), MWROs not observed (n=36)). These results are consistent with the hypothesis that RTN-pF neurons are elements of a distributed network responsible for MWRO generation and coordination of respiratory and vasomotor rhythms (Montano et al. 1996). Support by NIH grant R37 NS019814.