脊髓刺激降低大白鼠血压心率机制的初步分析

PRELIMINARY OBSERVATION OF THE MECHANISM OF DEPRESSOR AND BRADYCARDIAC EFFECTS IN RATS ON SPINAL CORD STIMULATION

在18只用戊巴比妥钠麻醉的大白鼠中,用一单电极在硬膜外正中线上刺激脊髓(SCS)。6只完整大白鼠表现为心率进行性逐渐减慢和血压即刻下降。在6只切除双侧颈迷走神经的大白鼠中,SCS同样引起相似的反应,但幅度较小。另外6只切去迷走神经且于C_7水平横断脊髓的大白鼠中,SCS引起与完整大白鼠几乎相同的反应。这表明SCS的降心率降血压效应是在脊髓水平直接抑制侧角交感神经元以及兴奋迷走中枢的结果。脊髓以上水平的心血管交感中枢也可能参与此过程,但其确切机制有待于进一步研究。

On eighteen rats anesthetized with pentobarbital intraperitoneally, spinal cord stimulation (SCS) was performed with a monopolar electrode placed at the posterior midline epidurally. Six intact rats showed instantaneous depressor effects and slow but progressive decline of heart rate after SCS. In six vagotomized rats, SCS also induced a similar response but was less in magnitude. In the other six rats, after vagotomy and transection of spinal cord at level of C7, SCS induced a response almost the same as in intact ones. This indicates that the bradyoardia and depressor effects of SCS are due to tho direct inhibiton of sympathetic neurons of the spinal cord lateral horns and excitation of vagal activity. The action of supraspinal cardiovascular sympathetic centre might also take part in the process, but its exact mechanism remains to be studied further.