A. Parasagittal schematic view of the rat RVLM. Abbreviations: Bot, pBot, rVRG, cVRG (the four subdivisions of the ventral respiratory column: Bötzinger, pre-Bötzinger, rostral ventral respiratory group and caudal VRG); RTN, retrotrapezoid nucleus (principal group of central respiratory chemoreceptors); CVLM, “caudal” VLM (location of GABAergic neurons that mediate the sympathetic baroreflex); lRT, lateral reticular nucleus. The approximate location of three subgroups of C1 cells is also shown. C1 and non-C1 RVLM pSNs are presumed to have the same general area of distribution.
B. Function of the three main groups of C1 cells located in the RVLM (color coding as in A). The C1 cells that project to the hypothalamus regulate vasopressin and ACTH release as well as sodium intake. The bulbospinal C1 cells are presympathetic for the most part. The third group of C1 cells regulate parasympathetic efferents.