Cardiovascular effects of angiotensin II in the rostral ventrolateral medulla: the push-pull hypothesis.
Neurons within the rostral ventrolateral medulla (RVLM) play a pivotal role in the tonic and phasic control of blood pressure. This region also contains a high density of angiotensin II type 1 (AT1) receptors. There is evidence that tonic activation of AT1 receptors in the RVLM contributes to an increased sympathetic vasomotor activity in some models of hypertension. At the same time, under certain conditions, activation of AT1 receptors in the RVLM can cause sympathoinhibition. In this review we argue that the effect of endogenous angiotensin II in the RVLM on sympathetic vasomotor activity depends upon the balance between tonic excitatory and inhibitory effects on sympathetic premotor neurons mediated by AT1 receptors within this region, and that this balance may be altered in different physiological or pathophysiological conditions.
Dampney
R A L
RA
Department of Physiology, School of Medical Sciences and Bosch Institute, The University of Sydney F13, NSW 2006, Australia. rogerd@physiol.usyd.edu.au
Tan
P S P
PS
Sheriff
M J
MJ
Fontes
M A P
MA
Horiuchi
J
J
D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure; D002320:Cardiovascular Physiological Phenomena; D006801:Humans; D006973:Hypertension / Q000378:metabolism / Q000503:physiopathology; D008526:Medulla Oblongata / Q000378:metabolism / Q000503:physiopathology*; D009474:Neurons / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D015398:Signal Transduction; D013564:Sympathetic Nervous System / Q000378:metabolism / Q000503:physiopathology
D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II