Angiotensin Receptors and the Vagal System

Angiotensin II (Ang II) is known to attenuate the vagal component of the baroreflex at both central and peripheral cardiac sites. Ang II receptor binding sites occur in both the nucleus of the solitary tract (NTS), where they are associated with vagal afferent terminals, and in the dorsal motor nucleus of vagus. In this study we have examined the distribution of Ang II binding sites in the cell bodies of vagal afferents in the nodose ganglion, and investigated whether these receptors are transported in the vagus nerve. Dense Ang II receptor binding was observed over neuronal cell bodies in the nodose ganglion and, in streaks, in the vagus nerve. Vagal ligation distal to the nodose ganglion resulted in a marked accumulation of receptor binding sites, proximal to the ligature, with a moderate increase on the distal side. These results demonstrate that Ang II receptor binding sites occur in the nodose ganglion and are transported centrally in the vagus to be located on presynaptic terminals in the NTS and also peripherally where they may occur on terminals of the vagus.