The sympathetic nervous system regulates cardiac output, blood pressure (BP), heart rate and volume, electrolyte balance and composition of body fluids. The afferent signals to the brain are regulated by mechanosensitive baroreceptors, volume sensors and chemoreceptors located in the vessels and in many other organs, particularly in the heart, kidney, lung, brain and muscles. Sympathetic nervous system outflow is coordinated by the nucleus tractus solitarius, located in the midbrain.1 Efferent sympathetic signals regulate BP, heart rate and cardiac output through beta (╬▓)-adrenergic receptors, and regulate peripheral resistance by vasoconstriction through alpha (╬▒)-adrenergic receptors. In the kidney, sodium and water retention is stimulated by activation of beta-adrenergic receptors in the proximal tubules.1