Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
Brain Res. 2010 Nov 4;1359:107-15. doi: 10.1016/j.brainres.2010.08.079. Epub 2010 Aug 31.
The aim of the present study was to investigate the effects of N(G)-nitro-L-arginine-methyl-ester (L-NAME) microinjected into the rostral nucleus tractus solitarius (NTS) on jejunal glucose, sodium and potassium absorption. Male Wistar rats (210-250 g, n=6-12) were anesthetized and submitted to midline laparotomy to expose and isolate 20 cm of jejunal loop and perform a subdiaphragmatic truncal vagotomy or sympathectomy. Either 0.9% NaCl or L-NAME (10 nmol 100 nl⁻¹) was microinjected into the rostral NTS using a stereotaxic instrument. Tyrode solution (pH 8) containing twice the usual concentrations of glucose, sodium and potassium was infused (0.5 ml min⁻¹) into the jejunal loop and samples were taken at 10-min intervals during the 40-min experiment. Results were expressed by the difference between influx and efflux. L-NAME into the NTS increased glucose absorption and decreased potassium absorption when compared to the saline group (38.8 ± 3.8 vs. 50.3 ± 3.3 mg/dl and 0.6±0.01 vs. 0.4 ± 0.03 mM, respectively; p<0.05). Sympathectomy inhibited the glucose absorption caused by L-NAME alone (50.3 ± 3.3 vs. 30.7 ± 4.6 mg/dl; p<0.05), whereas vagotomy inhibited the L-NAME effect on potassium absorption (0.40 ± 0.02 vs. 0.70 ± 0.05; p<0.05). Moreover, increased sodium absorption was observed only in the group that received 30 nmol of L-NAME into NTS (33.0 ± 4.2 vs. 48.4 ± 3.9). In conclusion, the results suggest the participation of endogenous nitric oxide (NO) in the NTS in modulating intestinal glucose and potassium absorption mediated by the autonomic nervous system.
本研究旨在探讨 N(G)-硝基-L-精氨酸甲酯（L-NAME）注入孤束核头端（NTS）对空肠葡萄糖、钠和钾吸收的影响。雄性 Wistar 大鼠（210-250g，n=6-12）麻醉后行正中剖腹术，暴露并分离 20cm 空肠袢，并进行膈下内脏大神经切断术或交感神经切除术。用立体定向仪将 0.9%NaCl 或 L-NAME（10nmol 100nl⁻¹）注入 NTS 头端。Tyrode 溶液（pH8）中葡萄糖、钠和钾的浓度是通常的两倍，以 0.5mlmin⁻¹的速度注入空肠袢，在 40min 实验期间，每隔 10min 取一次样本。结果用流入和流出的差值表示。与盐水组相比，L-NAME 注入 NTS 增加了葡萄糖的吸收，减少了钾的吸收（38.8±3.8 与 50.3±3.3mg/dl 和 0.6±0.01 与 0.4±0.03mM，分别；p<0.05）。交感神经切断术抑制了 L-NAME 单独引起的葡萄糖吸收（50.3±3.3 与 30.7±4.6mg/dl；p<0.05），而迷走神经切断术抑制了 L-NAME 对钾吸收的影响（0.40±0.02 与 0.70±0.05；p<0.05）。此外，只有在 NTS 接受 30nmol L-NAME 的组中观察到钠吸收增加（33.0±4.2 与 48.4±3.9）。总之，结果表明内源性一氧化氮（NO）参与了 NTS 对自主神经系统介导的空肠葡萄糖和钾吸收的调节。
