Fig. 6.

The strength of central respiratory drive influences the effect of glutamate receptor antagonism in the CVLM. A: rats with diminished central respiratory drive (reduced Pco₂; n = 5) and rats with enhanced central respiratory drive (elevated Pco₂; n = 5) experience equivalent increases in SNA after unloading the baroreceptors by infusion of SNP. B: microinjection of Kyn into the CVLM during SNP infusion results in a larger increase in SNA in animals with elevated Pco₂. Baseline SNA was determined during SNP infusion, immediately before Kyn injection into the CVLM. *P < 0.05, significant difference between groups with reduced and elevated Pco₂.