Time course of changes in mean arterial pressure (MAP) (A) evoked by intra-RVLM WIN55,212-2 (0.1 µg/ 200 pmol) (Veh+WIN55) in conscious rats pretreated, 10 min earlier, with the selective OX1R antagonist SB-408124 (1 nmol, intra-RVLM) (SB-408+WIN55). Values are mean±S. E.M. of 6 observations. *p< 0.05 versus respective “SB-408124+WIN55” values. (B) Changes in orexin-A level in treated (microinjected side; black bars) or non-treated (contralateral control side; open bars) RVLM of two groups of animals that received one of the following intra-RVLM treatments: (vehicle+WIN55,212-2; n=6) or (SB-408124+WIN55,212-2; n=6). Bar graphs represent mean±S. E.M. Data analyzed by unpaired Student-t test. * or #P<0.05 compared to the control RVLM.