Figure 2. A, Tracings from one rat showing the cardiovascular and respiratory responses to nucleus raphe obscurus (NRO) stimulation (10 s at 100 Hz, 60 µA, and 1-ms pulse duration) before and after bilateral microinjection of kynurenic acid (Kyn, 2.7 nmol/200 nl) within the rostral ventrolateral medulla (RVLM). BP, pulsatile blood pressure; MAP, mean arterial BP; HR, heart rate; Resp, respiration. The triangles denote electrical stimulations, and the arrow indicates microinjection. B, The left representative section shows the location of the NRO stimulation site. The illustration on the right shows the injection site within the RVLM.