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Organum Vasculosum of the Lamina Terminalis Detects NaCl to Elevate Sympathetic Nerve Activity and Blood Pressure.


ABSTRACT: High-salt diet elevates NaCl concentrations in the cerebrospinal fluid to increase sympathetic nerve activity (SNA) in salt-sensitive hypertension. The organum vasculosum of the lamina terminalis (OVLT) resides along the rostral wall of the third ventricle, lacks a complete blood-brain barrier, and plays a pivotal role in body fluid homeostasis. Therefore, the present study used a multifaceted approach to examine whether OVLT neurons of Sprague-Dawley rats are intrinsically sensitive to changes in extracellular NaCl concentrations and mediate the sympathoexcitatory responses to central NaCl loading. Using in vitro whole-cell recordings, step-wise increases in extracellular NaCl concentrations (2.5-10 mmol/L) produced concentration-dependent excitation of OVLT neurons. Additionally, these excitatory responses were intrinsic to OVLT neurons because hypertonic NaCl evoked inward currents, despite pharmacological synaptic blockade. In vivo single-unit recordings demonstrate that the majority of OVLT neurons (72%, 13/19) display concentration-dependent increases in neuronal discharge to intracarotid (50 ?L/15 s) or intracerebroventricular infusion (5 ?L/10 minutes) of hypertonic NaCl. Microinjection of hypertonic NaCl (30 nL/60 s) into the OVLT, but not adjacent areas, increased lumbar SNA, adrenal SNA, and arterial blood pressure in a concentration-dependent manner. Renal SNA decreased and splanchnic SNA remained unaffected. Finally, local inhibition of OVLT neurons with the GABAA receptor agonist muscimol (24 nL/10 s) significantly attenuated the sympathoexcitatory and pressor responses to intracerebroventricular infusion of 0.5 mol/L or 1.0 mol/L NaCl. Collectively, these findings indicate that OVLT neurons detect changes in extracellular NaCl concentrations to selectively alter SNA and raise arterial blood pressure.

SUBMITTER: Kinsman BJ 

PROVIDER: S-EPMC5794027 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Organum Vasculosum of the Lamina Terminalis Detects NaCl to Elevate Sympathetic Nerve Activity and Blood Pressure.

Kinsman Brian J BJ   Simmonds Sarah S SS   Browning Kirsteen N KN   Stocker Sean D SD  

Hypertension (Dallas, Tex. : 1979) 20161128 1


High-salt diet elevates NaCl concentrations in the cerebrospinal fluid to increase sympathetic nerve activity (SNA) in salt-sensitive hypertension. The organum vasculosum of the lamina terminalis (OVLT) resides along the rostral wall of the third ventricle, lacks a complete blood-brain barrier, and plays a pivotal role in body fluid homeostasis. Therefore, the present study used a multifaceted approach to examine whether OVLT neurons of Sprague-Dawley rats are intrinsically sensitive to changes  ...[more]

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