Wilson L B, Engbretson J
Department of Physiology, University of South Alabama College of Medicine, MSB 3024, Mobile, AL 36688, USA.
Auton Neurosci. 2000 Dec 28;86(1-2):135-9. doi: 10.1016/S1566-0702(00)00207-1.
Recent work from our laboratory suggests that nitric oxide production in the dorsal horn has a modulatory influence on the pressor reflex evoked by static contraction of skeletal muscle. In this study, we tested the hypothesis that nitric oxide production in the dorsal horn is involved in producing the pressor reflex elicited by activation of skeletal muscle mechanoreceptors. Cats were anesthetized with alpha-chloralose (80 mg/kg) and urethane (100 mg/kg) and a laminectomy was performed. With the exception of the L7 dorsal root, the dorsal and ventral roots from L5 to S2 were sectioned on one side. Muscle mechanoreceptors were activated by manually stretching the ipsilateral triceps surae muscle 1.5 cm. To block nitric oxide synthase, a 50 mM solution of nt-nitro-L-argenine methyl ester (L-NAME) (a dose that altered the pressor reflex to static contraction) was microdialyzed into the dorsal horn at L6 and S1. Dialysis of L-NAME failed to attenuate the peak change in mean arterial pressure evoked by muscle stretch (45 +/- 6 mmHg before and 44 +/- 9 mmHg after 2 h of L-NAME dialysis). On the other hand, 2 h of L-arginine dialysis (50 mM) increased the peak pressor response to muscle stretch from 43 +/- 3 to 57 +/- 5 mmHg. These data suggest that administration of L-arginine enhances the excitability of dorsal horn cells receiving input from muscle mechanoreceptors, thus increasing the pressor response evoked by activation of this type of muscle afferent neuron.
我们实验室最近的研究表明，背角中一氧化氮的产生对骨骼肌静态收缩诱发的升压反射具有调节作用。在本研究中，我们检验了以下假设：背角中一氧化氮的产生参与了由骨骼肌机械感受器激活所引发的升压反射。猫用α-氯醛糖（80mg/kg）和乌拉坦（100mg/kg）麻醉后进行椎板切除术。除L7背根外，一侧切断L5至S2的背根和腹根。通过手动拉伸同侧腓肠三头肌1.5厘米来激活肌肉机械感受器。为了阻断一氧化氮合酶，将50mM的Nω-硝基-L-精氨酸甲酯（L-NAME）溶液（一种能改变对静态收缩的升压反射的剂量）微透析到L6和S1的背角中。L-NAME微透析未能减弱肌肉拉伸诱发的平均动脉压峰值变化（L-NAME微透析2小时前为45±6mmHg，2小时后为44±9mmHg）。另一方面，L-精氨酸微透析2小时（50mM）使对肌肉拉伸的升压反应峰值从43±3mmHg增加到57±5mmHg。这些数据表明，给予L-精氨酸可增强接受来自肌肉机械感受器输入的背角细胞的兴奋性，从而增加由这类肌肉传入神经元激活所诱发的升压反应。
