Fig. 1.

Microinjection sites in the caudal subpostremal nucleus tractus solitarii (NTS) for all experiments. Schematic diagrams of transverse sections of the medulla oblongata from a rat brain are shown. AP, area postrema; c, central canal; 10, dorsal motor nucleus of the vagus nerve; 12, nucleus of the hypoglossal nerve; ts, tractus solitarius; Gr, gracile nucleus; Cu, cuneate nucleus. Scale is shown at the bottom; the number on the left side of the schematic diagram denotes the rostro-caudal position in millimeters of the section relative to the obex according to the atlas of the rat subpostremal NTS by Barraco et al. (Ref. 1). Microinjection sites were marked with fluorescent dye and are denoted with filled symbols for the pressor responses to N⁶-cyclopentyladenosine (CPA) and corresponding open symbols for the depressor responses. A: microinjections of CPA in intact animals (●, ○), after vasopressin V₁ receptor blockade (VX; ◊), lumbar sympathectomy plus VX (LX + VX_i; ▴, ▵), and after angiotensin II AT₁ receptor blockade (ATX; ■, □). B: microinjections of CPA after bilateral adrenalectomy (ADX) plus ganglionic blockade (GX) (▴), following ADX + GX + VX (dotted closed circle, dotted open circle), after ADX + GX + VX + ATX (dotted closed square, dotted open square). In experiments where vasopressin assay was performed, the microinjection sites were denoted: + and x for CPA and artificial cerebrospinal fluid (ACF) microinjections, respectively.