Role of the caudal pressor area in the regulation of sympathetic vasomotor tone

R.R Campos,N.F Silva,A.M Silva,B.A Carillo,E.B Oliveira-Sales,H.A Futuro Neto,C.T Bergamaschi

doi:10.1590/s0100-879x2008000700002

Abstract

It is well known that the ventrolateral medulla contains neurons involved in the tonic and reflex control of the cardiovascular system. Two regions within the ventrolateral medulla were initially identified: the rostral ventrolateral medulla (RVLM) and the caudal ventrolateral medulla (CVLM). Activation of the RVLM raises arterial blood pressure and sympathetic nerve activity, and activation of the CVLM causes opposite effects. The RVLM premotor neurons project directly to sympathetic preganglionic neurons and are involved in the maintenance of resting sympathetic vasomotor tone. A significant proportion of tonic activity in the RVLM sympathetic premotor neurons is driven by neurons located in a third region of the ventrolateral medulla denominated caudal pressor area (CPA). The CPA is a pressor region located at the extreme caudal part of the ventrolateral medulla that appears to have an important role controlling the activity of RVLM neurons. In this brief review, we will address the importance of the ventrolateral medulla neurons for the generation of resting sympathetic tone related to arterial blood pressure control focusing on two regions, the RVLM and the CPA.

Highlights

Sympathetic vasomotor outflow is composed of efferent pathways that control vascular tone and cardiac output, playing an essential role in maintaining the constancy of blood pressure and bodily homeostasis
We address the question of the importance of ventrolateral medulla neurons in the generation of the sympathetic vasomotor tone focusing on two regions, the rostral ventrolateral medulla (RVLM) and the caudal pressor area (CPA)
The CPA is a pressor region located at the extreme caudal part of the caudal ventrolateral medulla (CVLM), which appears to have an important role in directly or indirectly controlling the activity of RVLM neurons

Summary

Introduction

Sympathetic vasomotor outflow is composed of efferent pathways that control vascular tone (vascular peripheral resistance) and cardiac output (contractility and heart rate), playing an essential role in maintaining the constancy of blood pressure and bodily homeostasis. Ventromedial medulla, c) caudal raphe nuclei, d) A5 cell group in the pons, and e) paraventricular nucleus of the hypothalamus (PVN) [2] Of these five nuclei, the PVN and the RVLM appear to have a tonic effect on the control of sympathetic vasomotor tone and are topographically organized [2,3,4,5]. The PVN and the RVLM appear to have a tonic effect on the control of sympathetic vasomotor tone and are topographically organized [2,3,4,5] In this brief review, we address the question of the importance of ventrolateral medulla neurons in the generation of the sympathetic vasomotor tone focusing on two regions, the RVLM and the caudal pressor area (CPA). The CPA is a pressor region located at the extreme caudal part of the caudal ventrolateral medulla (CVLM), which appears to have an important role in directly or indirectly controlling the activity of RVLM neurons

Rostral ventrolateral medulla

Caudal pressor area