PHYSIOLOGICAL AND PATHOPHYSIOLOGICAL MECHANISMS DETERMINIG THE SYMPATHETIC VASOMOTOR TONE

Abstract

The sympathetic vasomotor activity is one of determinants of blood pressure (BP). Understanding the mechanisms involved in the control of the cardiovascular system is important in physiological and pathophysiological condition. The principal sympathetic premotor brain nuclei are confined in the paraventricular nucleus of hypothalamus (PVN) and in the rostralventrolateral medulla (RVLM). In different patophysiological condition, there is an increase in the sympathetic vasomotor tone, in part due to an increase in the activity of the PVN and RVLM neurons. In this brief review, we discussed the major mechanisms of sympathetic activation in different experimental models: 1) renovascular hypertension, 2) renoprival hypertension, 3) cardiac failure, 4) hypertension induced by nitric oxide blockade, 5) obesity and 6) gender differences. The actions of different mediators in the PVN and in the RVLM acting in long term, can change the level of sympathetic nerve activity and blood pressure and therefore, contributing for the progression of cardiovascular disease.