Yardley C P, Fitzsimons C L, Weaver L C
John P. Robarts Research Institute, University of Western Ontario, London, Canada.
Am J Physiol. 1989 Nov;257(5 Pt 2):H1347-53. doi: 10.1152/ajpheart.1989.257.5.H1347.
On transection of the cervical spinal cord, substantial decreases in systemic arterial pressure and in discharge of many sympathetic nerves suggest the absence of sympathetic support to the cardiovascular system. However, discharge of mesenteric and splenic nerves is well maintained in spinal cats (R. L. Meckler and L. C. Weaver. J. Physiol. Lond. 396: 139-153, 1988; R. D. Stein and L. C. Weaver. J. Physiol. Lond. 396: 155-172, 1988). We proposed that the low arterial pressure in spinal animals was caused predominantly by decreased cardiac output and vasodilation in muscle and some visceral vascular beds but that sustained mesenteric and splenic discharge was causing significant splanchnic vasoconstriction and partial support of arterial pressure. Therefore, changes in cardiac output, total peripheral resistance, and resistance of constant-flow-perfused mesenteric visceral and hindlimb skeletal muscle vascular beds caused by interruption of cervical spinal pathways were assessed. Blockade of cervical pathways decreased arterial pressure as much by decreasing cardiac output as by decreasing total peripheral resistance. Resistances of the muscle and mesenteric vascular beds decreased equally. In conclusion, hypotension in spinal cats is caused by decreased cardiac output and by vasodilation, which is as prominent in mesenteric as it is in muscle vascular beds. The maintained mesenteric sympathetic discharge in spinal cats appears unable to produce significant support of vascular arterial resistance.
在颈脊髓横断后，体循环动脉压大幅下降，许多交感神经的放电减少，这表明心血管系统缺乏交感神经支持。然而，在脊髓猫中，肠系膜神经和脾神经的放电仍维持良好（R.L.梅克勒和L.C.韦弗，《伦敦生理学杂志》396: 139 - 153, 1988；R.D.斯坦和L.C.韦弗，《伦敦生理学杂志》396: 155 - 172, 1988）。我们提出，脊髓动物的动脉压低主要是由于心输出量减少以及肌肉和一些内脏血管床的血管舒张，但肠系膜和脾神经的持续放电导致显著的内脏血管收缩并部分维持动脉压。因此，评估了颈脊髓通路中断引起的心输出量、总外周阻力以及恒流灌注的肠系膜内脏和后肢骨骼肌血管床阻力的变化。阻断颈脊髓通路通过降低心输出量和降低总外周阻力对动脉压的降低作用相同。肌肉和肠系膜血管床的阻力同等程度降低。总之，脊髓猫的低血压是由心输出量减少和血管舒张引起的，肠系膜血管床的血管舒张与肌肉血管床的血管舒张同样显著。脊髓猫中肠系膜交感神经放电的维持似乎无法显著支持血管动脉阻力。
