Effects of NMDA on (A) VI, (B) fR and (C) VT in the presence (continuous lines) or absence (dotted lines) of the NMDAR antagonist MK801. Effects of AMPA on (D) VI, (E) fR and (F) VT in the presence (continuous lines) or absence (dotted lines) of the AMPAR antagonist NBQX. Arrow indicates injection of NMDA or AMPA into the NTS. All measurements were made in 21% O2. Data are mean ± s.e.m.
n = 6 CON and eight CSH rats for NMDA experiments and four CON and six CSH for AMPA experiments. *Significance from control value before injection (Con) (P < 0.05). CON, controls; CSH, chronic sustained hypoxia; fR, breathing frequency; VI, total minute ventilation; VT, tidal volume.