[Functions and changes of chemoreflex in physiological and pathological conditions]

Chemoreceptors are known to respond to changes in composition of the gases in the inspired air by changing pulmonary ventilation. Whereas, less known it is the role that they play in many both physiologic and pathologic conditions. In this review we do not only consider the anatomic and physiologic chemoreceptor features but also we analyse the relationship between chemoreflex and baroreflex in the cardiovascular control, their role in the pathogenesis of essential hypertension and in the increase of blood pressure in subjects affected by obstructive sleep apnea, their implication in the genesis of dyspnea in chronic heart failure and their role in pulmonary disease. In this review we also analyse the chemoreflex changes with relation to physiologic situations such as aging, obesity, exercise, training and high altitude. Three methods are described for the study of the chemoreflex function, but more attention is paid to the new rebreathing technic. The aim of this paper is to underline the interactions between chemoreceptors and cardiovascular system and to analyse their functional changes in both physiologic and pathologic conditions.