It's enough to raise your blood pressure!

Abstract

Constant activity in your sympathetic nervous system is one of the reasons that your blood pressure is maintained within healthy limits. Ongoing activity in sympathetic nerves that innervate blood vessels leads to a degree of contraction of these vessels and consequently to vasomotor tone. How this basal activity in the sympathetic nervous system is generated is something of a mystery, but there are several lines of evidence implicating a role for the C1 adrenergic neurones in the rostral ventrolateral medulla (RVLM): first, the location of the C1 neurones coincides with the region of the RVLM that regulates arterial pressure; second, the spinally projecting axons of C1 neurones innervate sympathetic preganglionic neurones, the output neurones for the sympathetic nervous system; third, the activity in C1 neurones is inhibited by increases in arterial blood pressure, allowing them to contribute to a reflex reduction in blood pressure by reducing sympathetic tone.