Hypertension due to increased salt levels have been shown to be associated with increased levels of Na in cerebrospinal fluid (CSF) and increased sympathetic nerve activity (SNA). This study focuses more so on the effects of hypernatremia in CSF on the rostral ventrolateral medulla (RVLM) and how it leads to an increase in arterial blood pressure (ABP) and SNA.
CSF with varying levels of Na concentrations were infused in male rats. During these infusions, recordings of the ABP and SNA were active.
The results showed concentration-dependent increases in lumbar SNA, adrenal SNA, heart rate, and mean ABP. To observe the role of the RVLM in the sympathoexcititory response, the RVLM was inhibited following the infusions of the CSF NaCl. A GABA agonist was then given to observe the acute effects of the CSF NaCl. Lumbar, renal, adrenal and splanchnic SNA was reduced in addition to mean ABP and heart rate.
The results led to the conclusions that acute infusions of different concentrations of NaCl increased lumbar SNA and adrenal SNA while decreasing renal SNA and not changing splanchnic SNA. In relation to the RVLM, sympathetic and ABP responses were reduced when the RVLM neurons were inhibited with a GABA agonist or glutamate receptor blockers. The sympathoexcitatory responses are deemed likely to be from end organs. When the RVLM neurons were inhibited, the sympathetic and pressor responses to the NaCl was reduced, explaining the role of the RVLM in ABP and SNA control.
This study has relation to our lab due to the questions surrounding the end responses the RVLM has on ABP and SNA. It was clear in this study that the responses were attenuated when the RVLM neurons were inhibited. That tells us that the RVLM does in fact have role in responding to the changes in SNA and ABP.
Questions:
- In experiment 1, it says that adrenal SNA was increased, but then in their concluding statements, they state that adrenal SNA was decreased. Can you help explain this?
-Tsetse Fly
No comments:
Post a Comment