AT1 Receptor Mediated Hypertensive Response to Ang II in the Nucleus Tractus Solitarii of Normotensive Rats Involves NO Dependent Local GABA Release

Conclusion: Our results suggest that the AT1R mediated hypertensive response to angiotensin II within the NTS in normotensive rats is GABA and NO dependent. Nitric oxide produced within the NTS tonically potentiates local GABA and glutamate release. Introduction The central nervous system network that regulates the level of sympathetic tone and, hence, blood pressure, is located in the brainstem and consists mainly of the rostral ventrolateral medulla (RVLM), the paraventricular nucleus (PVN) of the hypothalamus and the nucleus tractus solitarii (NTS) (Guyenet, 2006). It is well-established that the RVLM, the so-called brainstem ‘pressor area,’ is a key site for the regulation of sympathetic tone and blood pressure (Dupont and Brouwers, 2010). The major source of excitatory sympathetic drive from the RVLM are spinally projecting glutamatergic neurons which receive tonic excitatory signals from other brain areas, including the PVN, and inhibitory signals from the caudal ventrolateral medulla (CVLM) and indirectly from the NTS (Guyenet, 2006). The NTS plays an important role in central cardiovascular regulation and is the principal site for the termination of baroreceptor afferent fibers mediating the inhibitory actions of baroreceptors in the arterial wall on sympathetic outflow (Paton and Kasparov, 1999; Guyenet, 2006). Stimulation of mechanosensitive baroreceptors by distension of the arterial wall following blood pressure elevation results in activatio...
Source: Frontiers in Pharmacology - Category: Drugs & Pharmacology Source Type: research