Acute inhibition of the hypothalamic paraventricular nucleus decreases renal sympathetic nerve activity and arterial blood pressure in water-deprived rats

被引:43
作者
Stocker, SD [1 ]
Keith, KJ [1 ]
Toney, GM [1 ]
机构
[1] Univ Texas, Hlth Sci Ctr, Dept Physiol, San Antonio, TX 78239 USA
关键词
dehydration; hypovolemia; hyperosmolality; angiotensin II; GABA(A) receptor;
D O I
10.1152/ajpregu.00494.2003
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The present study was performed to determine whether sympathetic outflow and arterial blood pressure in water-deprived rats are dependent on the ongoing neuronal activity of the hypothalamic paraventricular nucleus (PVN). Renal sympathetic nerve activity (RSNA), mean arterial blood pressure ( MAP), and heart rate were recorded in urethane-alpha-chloralose-anesthetized rats that were deprived of water but not food for 48 h before experiments. Acute inhibition of the PVN by bilateral microinjection of the GABA(A) agonist muscimol ( 100 pmol/side) significantly decreased RSNA in water-deprived rats ( - 26.7 +/- 4.7%, n = 7) but was without effect in control rats (1.3 +/- 6.3%, n = 7). Similarly, injection of muscimol produced a greater decrease in MAP in water-deprived rats than in control rats ( - 46 +/- 3 vs. - 16 +/- 3 mmHg, respectively), although baseline MAP was not different between groups ( 105 +/- 4 vs. 107 +/- 4 mmHg, respectively). Neither bilateral microinjection of isotonic saline vehicle ( 100 nl/side) into the PVN nor muscimol ( 100 pmol/side) outside the PVN altered RSNA or MAP in either group. In addition, ganglionic blockade with hexamethonium ( 30 mg/kg iv) significantly decreased MAP in both groups; however, the decrease in MAP was significantly greater in water-deprived rats than in control rats ( 62 +/- 2 vs. 48 +/- 2 mmHg, respectively). Collectively, these findings suggest that sympathetic outflow contributes more to the maintenance of blood pressure in the water-deprived rat, and this depends, at least partly, on the ongoing activity of PVN neurons.
引用
收藏
页码:R719 / R725
页数:7
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