Gender differences in the neurohumoral control of the cardiovascular system.

The cardiovascular system is regulated by many complex neurohumoral mechanisms which ensure the cardiac, cerebral and renal functions. The nervous control of the heart is mainly mediated by the vagal and sympathetic systems and by their interaction, known as the sympatho-vagal balance. An increased sympathetic tone is found in many abnormal situations, such as arterial hypertension, diabetes, chronic heart failure and myocardial infarction, and is associated with an increase in over-all mortality. The hormonal control of the cardiovascular system is mediated by various substances such as renin-angiotensin, catecholamines, insulin and estrogens, that are themselves correlated with the autonomic nervous system. In contrast to men, fertile women show a predominant vagal tone. Sex-related differences in the neurohumoral control of the cardiovascular system have been demonstrated during physical effort and in the hemodynamic adaptation to orthostatism. They have been postulated to explain the lower mortality in women compared to men among hypertensive or chronic heart failure patients. Prospective studies are needed to better define the gender differences in the pathophysiological mechanisms underlying cardiovascular diseases, in order to refine prevention and therapy.