RENAL SYMPATHETIC NERVE ACTIVITY DURING SHOCK

1998~1999年间，在所有反射完整的清醒兔(INT)、去窦主动脉压力感受器神经(BRD)或去心脏神经(CND)后，观察了肾交感神经活动(RNA)对急性心脏压塞(CT)的反应。在INT兔中，在CT开始时的平均动脉压(MAP)期间，RNA升高到200%以上，而RNA下降到一半以下，同时MAP在随后注射生理盐水后急剧下降。如果在CT发作前给予7-硝基吲哚，则可明显阻止失代偿CT引起的RNA下降，大脑皮质和延髓的一氧化氮合酶活性分别受到48%和44%的抑制。在BRD兔中，RNA在整个CT过程中没有改变，但在注射纳洛酮后增加。在CND兔中，核糖核酸在代偿CT期间增加，但在…失活时不减少这些结果表明，CT对RNA的反应是双相的，在CT代偿期增加，在失代偿期减少。窦主动脉压力感受器参与调节RNA的增加，而心脏受体可能参与调节RNA的减少。失代偿期CT时RNA的突然减少可能由NO或中枢神经系统内源性阿片类物质介导。2000年，有人研究了心源性休克或失血性休克对RNA和压力反射的影响。CT使核糖核酸开始升高，然后下降到基线以下。切断迷走神经后，压力感受器反射衰减消失。然而，失血性休克最初增加了RNA，随后恢复到基线水平。颈迷走神经切断术在两次休克时均维持较高水平的RNA水平。压力反射敏感性在释放CT后即刻显著减弱，与CT相比，出血恢复后压力反射敏感性并未减弱。这些结果表明，CT对交感神经活动的抑制比出血更严重，心源性休克通过迷走神经传入减弱压力感受性反射。较少

During 1998-1999, renal sympathetic nerve activity (RNA) responses to acute cardiac tamponade (CT) were studied in conscious rabbits with all reflexes intact (INT) or after sinoaortic baroreceptor denervation (BRD) or cardiac nerve denervation (CND). In INT rabbits, the RNA increased to over 200% during the mean arterial pressure (MAP) mentained when the CT was started, whereas the RNA decreased to below half and at the same time the MAP decreased sharply by subsequent injection of saline. After that, an administration of naloxone resulted in increases in both MAP and RNA.If 7-nitroindazole was admitted before the biginning of CT, the decline in RNA caused by decompensated CT was markedly prevented and brain nitric oxide synthase activity in the cerebral cortex and medulla oblongata was inhibited by 48% and 44%. In BRD rabbits, RNA did not alter throughout CT, but increased on injection of naloxone. In CND rabbits, RNA increased during compensated CT but did not decrease during decompe … More nsated CT.These results indicate that RNA responses to CT are biphasic, with an increase during conpensated CT and a decrease during decompensated CT.Sinoaortic baroreceptors are involved in mediating the increase in RNA, whereas cardiac receptors may be involved in mediating the decrease in RNA The abrupt decrease in RNA during decompensated CT may be mediated by NO or endogenous opioid in the central nervous system.In 2000, it was studied that the effects of cardiogenic or hemorrhagic shock on RNA and baroreflex. CT increased RNA initially, followed by decline below baseline. Vagotomy abolished the baroreflex attenuation. However, hemorrhagic shock increased RNA initially, followed by recovery toward baseline. Cervical vagotomy maintained RNA at higher level than those of INT rabbits on both shock. The baroreflex sensitivity was significantly attenuated soon after releasing CT.In contrast to CT, the baroreflex sinsitivity was not attenuated after hemorrhage recovering. These results indicated that sympathetic nerve activity may be attenuated more heavily in CT than hemorrhage, and cardiogenic shock attenuated the baroreflex via vagal afferents. Less