Neurons in the Organum Vasculosum of the Lamina Terminalis Sense NaCl and Angiotensin II to Regulate Sympathetic Nerve Activity and Arterial Blood Pressure.

The organum vasculosum of the lamina terminalis (OVLT) contains specialized neurons that sense changes in extracellular NaCl concentrations to regulate sympathetic nerve activity (SNA) and arterial blood pressure (ABP). However, OVLT neurons also abundantly express angiotensin II (AngII)-type I receptors. Therefore, we performed a series of in vitro and in vivo studies in adult male Sprague-Dawley rats to determine whether OVLT neurons sense both NaCl and AngII to impact SNA and ABP. First, in vitro whole-cell recordings revealed the majority of OVLT neurons (66%, 23/35) showed an increased discharge frequency to both +7.5mM NaCl (1.1±0.2 to 2.2±0.3Hz, Pu003c0.001) and 100pM AngII (1.3±0.3 to 2.2±0.3Hz, Pu003c0.001). Second, in vivo single-unit recordings demonstrate the majority of OVLT neurons (61%, 11/18) displayed an increase in cell discharge to intracarotid injection of 0.5M NaCl (3.6±0.6 to 9.0±1.6Hz, Pu003c0.01) and 200ng AngII (3.2±0.7 to 9.2±1.9Hz, Pu003c0.01). Third, optogenetic inhibition of OVLT neurons (rAA...