The caudal solitary complex is a site of central CO2 chemoreception and integration of multiple systems that regulate expired CO2

The solitary complex is comprised of the nucleus tractus solitarius (NTS, sensory) and dorsal motor nucleus of the vagus (DMV, motor), which functions as an integrative center for neural control of multiple systems including the respiratory, cardiovascular and gastroesophageal systems. The caudal NTS-DMV is one of the several sites of central CO2 chemoreception in the brain stem. CO2 chemosensitive neurons are fully responsive to CO2 at birth and their responsiveness seems to depend on pH-sensitive K+ channels. In addition, chemosensitive neurons are highly sensitive to conditions such as hypoxia (e.g., neural plasticity) and hyperoxia (e.g., stimulation), suggesting they employ redox and nitrosative signaling mechanisms. Here we review the cellular and systems physiological evidence supporting our hypothesis that the caudal NTS-DMV is a site for integration of respiratory, cardiovascular and gastroesophageal systems that work together to eliminate CO2 during acute and chronic respiratory acidosis to restore pH homeostasis. (C) 2010 Elsevier B.V. All rights reserved.