The Distribution of Substance P in the Canine Dorsomedial Medulla: PDF OnlyBlock Christine H.; Barnes, Karen L.; Ferrario, Carlos M.Journal of Cardiovascular Pharmacology: 1987 - p S230-S234 Free Abstract Summary: To define the neurochemical substrates underlying cardiovascular regulatory mechanisms in the canine dorsal medulla, we characterized immunocytochemically the organization of substance P (SP) in the dorsomedial medulla. Substance P immunoreactivity was the most dense in the dorsal nucleus tractus solitarii (nTS). Varicose fibers and cells containing this neuropeptide were localized in the dorsal motor nucleus of the vagus (dmnX) and nucleus commissuralis. A few scattered fibers were observed within the area postrema. The distribution of this peptide suggests a topographical organization within the dorsomedial medulla of the dog that is closely related to the cytoarchitectural organization. In addition, the patterns of SP immunoreactivity overlap the distribution of vagal afferent fibers. These observations are discussed in relation to the possible function of SP in the dorsomedial medulla. Address correspondence and reprint requests to Dr. C. H. Block, Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44106, U.S.A. © Lippincott-Raven Publishers.