Functional Connection From the Surface Chemosensitive Region to the Respiratory Neuronal Network in the Rat Medulla
説明
Although the ventral medullary surface (VMS) has previously been assumed to be the main site for central respiratory chemoreception in mammals, it has recently been argued that chemosensitive sites are widespread in the lower brainstem, including the deep medullary regions1, 2, 3 (also see the reviews4, 5, 6). However, c-fos immunocytological studies have shown that CO2-activated cells are primarily located in the superficial ventral medulla.7, 8, 9 We have also recently suggested that the small cells surrounding fine vessels in the most superficial layer of the ventral medulla are the CO2 chemoreceptor cells.10 We also assume that there must be a neural connection from the VMS to the respiratory rhythm and pattern generating neuronal network, e.g., to the ventral respiratory group (VRG) region of the medulla. Here we analyze the respiratory output responses to local electrical or chemical stimulation at various sites in the VMS to establish a functional connection from the VMS to the respiratory neuronal network.