Tonic cardiovascular effects of angiotensin II in the ventrolateral medulla.
- 1 March 1990
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Hypertension
- Vol. 15 (3), 274-283
- https://doi.org/10.1161/01.hyp.15.3.274
Abstract
The rostral and caudal parts of the ventrolateral medulla play a major role in the control of blood pressure. Both regions contain a high density of receptor binding sites for angiotensin II, and it has been shown previously that microinjection of angiotensin II into the rostral ventrolateral medulla causes a rise in blood pressure. The aims of this study were to determine the cardiovascular effects of microinjection of angiotensin II and its specific antagonist [Sar1Thr8]angiotensin II into the caudal ventrolateral medulla and to characterize the regional vascular effects elicited by both compounds in the rostral ventrolateral medulla. Microinjections of angiotensin II (0.2-20 pmol) into histologically verified sites in the caudal ventrolateral medulla of anesthetized baroreceptor-denervated rabbits produced dose-dependent decreases in blood pressure and renal sympathetic nerve activity, whereas microinjection of [Sar1Thr8]angiotensin II (40 pmol) produced increases in these variables. In the rostral ventrolateral medulla, angiotensin II (0.02-20 pmol) elicited a dose-dependent increase in blood pressure, iliac vascular resistance, and renal sympathetic nerve activity, whereas [Sar1Thr8]angiotensin II (40 pmol) produced decreases in these variables. The effects on heart rate elicited by either compound in the rostral or caudal ventrolateral medulla were small but were in the same direction as the other cardiovascular variables. In contrast, angiotensin II had no detectable effect on sympathoexcitatory neurons within the rostral dorsomedial medulla, a region that lacks angiotensin II receptor binding sites. The results indicate that endogenous angiotensin II acts on specific receptors within the rostral and caudal parts of the ventrolateral medulla and has a tonic excitatory action on sympathoexcitatory and sympathoinhibitory neurons within these respective regions.This publication has 30 references indexed in Scilit:
- Origin of tonic GABAergic inputs to vasopressor neurons in the subretrofacial nucleus of the rabbitJournal of the Autonomic Nervous System, 1988
- Afferent connections and spinal projections of the pressor region in the rostral ventrolateral medulla of the catJournal of the Autonomic Nervous System, 1987
- Angiotensin II receptors and angiotensin converting enzyme in the medulla oblongata.Hypertension, 1987
- Functions of Angiotensin in the Central Nervous SystemAnnual Review of Physiology, 1987
- Identification and properties of sub-retrofacial bulbospinal neurones: a descending cardiovascular pathway in the catJournal of the Autonomic Nervous System, 1986
- Distribution of tyrosine hydroxylase and neuropeptide Y–like immunoreactive neurons in rabbit medulla oblongata, with attention to colocalization studies, presumptive adrenaline‐synthesizing perikarya, and vagal preganglionic cellsJournal of Comparative Neurology, 1986
- Vasopressor neurons in the rostral ventrolateral medulla of the rabbitJournal of the Autonomic Nervous System, 1985
- Organization of Angiotensin II Immunoreactive Cells and Fibers in the Rat Central Nervous SystemNeuroendocrinology, 1985
- Adrenaline neurons in the rostral ventrolateral medulla innervate thoracic spinal cord: A combined immunocytochemical and retrograde transport demonstrationNeuroscience Letters, 1981
- Distribution of catecholamine-containing cell bodies in the rabbit central nervous systemJournal of Comparative Neurology, 1978