TY - JOUR
T1 - The baroreflex and beyond
T2 - Control of sympathetic vasomotor tone by gabaergic neurons in the ventrolateral medulla
AU - Schreihofer, Ann M.
AU - Guyenet, Patrice G.
PY - 2002
Y1 - 2002
N2 - 1. Barosensitive, bulbospinal neurons in the rostral ventro-lateral medulla (RVLM), which provide the major tonic excitatory drive to sympathetic vasomotor neurons, are prominently inhibited by GABA. 2. A major source of the GABAergic inhibition to pre-sympathetic RVLM neurons arises from an area immediately caudal to the RVLM, known as the caudal ventrolateral medulla (CVLM). 3. Arterial baroreceptor afferents projecting to the nucleus tractus solitarius (NTS) provide a major tonic excitatory input to GABAergic CVLM neurons. These CVLM cells are a critical component for baroreflex-mediated changes in presympathetic RVLM neuronal activity, sympathetic nerve activity (SNA) and arterial pressure (AP). 4. Some GABAergic CVLM neurons are tonically activated by inputs independent of arterial baroreceptors or the NTS, providing a GABAergic-mediated inhibition of the presympathetic RVLM neurons that is autonomous of baroreceptor inputs. 5. GABAergic CVLM neurons appear to play two distinct, yet important, roles in the regulation of sympathetic vasomotor tone and AP. They dampen immediate changes in AP via the baroreflex and tonically inhibit the activity of the presympathetic RVLM neurons by baroreceptor-independent mechanisms. This baroreceptor-independent, GABAergic inhibition of presympathetic RVLM neurons may play an important role in determining the long-term level of sympathetic vasomotor tone and AP.
AB - 1. Barosensitive, bulbospinal neurons in the rostral ventro-lateral medulla (RVLM), which provide the major tonic excitatory drive to sympathetic vasomotor neurons, are prominently inhibited by GABA. 2. A major source of the GABAergic inhibition to pre-sympathetic RVLM neurons arises from an area immediately caudal to the RVLM, known as the caudal ventrolateral medulla (CVLM). 3. Arterial baroreceptor afferents projecting to the nucleus tractus solitarius (NTS) provide a major tonic excitatory input to GABAergic CVLM neurons. These CVLM cells are a critical component for baroreflex-mediated changes in presympathetic RVLM neuronal activity, sympathetic nerve activity (SNA) and arterial pressure (AP). 4. Some GABAergic CVLM neurons are tonically activated by inputs independent of arterial baroreceptors or the NTS, providing a GABAergic-mediated inhibition of the presympathetic RVLM neurons that is autonomous of baroreceptor inputs. 5. GABAergic CVLM neurons appear to play two distinct, yet important, roles in the regulation of sympathetic vasomotor tone and AP. They dampen immediate changes in AP via the baroreflex and tonically inhibit the activity of the presympathetic RVLM neurons by baroreceptor-independent mechanisms. This baroreceptor-independent, GABAergic inhibition of presympathetic RVLM neurons may play an important role in determining the long-term level of sympathetic vasomotor tone and AP.
KW - Baroreceptor reflex
KW - Blood pressure regulation
KW - Brain stem
KW - C1 cell group
KW - GABA
KW - Sympathetic vasomotor tone
UR - http://www.scopus.com/inward/record.url?scp=0036090835&partnerID=8YFLogxK
U2 - 10.1046/j.1440-1681.2002.03665.x
DO - 10.1046/j.1440-1681.2002.03665.x
M3 - Article
C2 - 12010201
AN - SCOPUS:0036090835
SN - 0305-1870
VL - 29
SP - 514
EP - 521
JO - Clinical and Experimental Pharmacology and Physiology
JF - Clinical and Experimental Pharmacology and Physiology
IS - 5-6
ER -