Figure 2. A summary of the quantitative analysis of the magnitude of recovered activity in the LPN in H-CBI and H-CBE after administration of DPCPX (only) or sequential administration of CGS-21680 followed by DPCPX is shown in this histogram. In both H-CBI and H-CBE animals, DPCPX induced recovery of respiratory-related activity in the LPN. The magnitude of recovery in H-CBI animals (42.6 ± 4.6%), whereas greater than that in H-CBE animals (38.4 ± 4.2%), was not statistically significant. However, the magnitude of DPCPX-induced recovery in H-CBI animals after prior CGS-21680 administration was significantly (P < 0.05) enhanced (compare H-CBI DPCPX only and H-CBI CGS-21680 + DPCPX). In contrast, the magnitude of DPCPX-induced recovery was not enhanced further by prior CGS-21680 administration in H-CBE animals. Statistical significance is shown by *P < 0.05 (Newman-Keuls comparison test).