Coote J H, Lewis D I
Department of Physiology, Medical School, University of Birmingham, UK.
J Physiol Pharmacol. 1995 Sep;46(3):259-71.
Populations of neurones containing noradrenaline, dopamine and possibly adrenaline project to the spinal cord where they innervate sympathetic preganglionic neurones (SPN). Studies are described which illustrate the actions of catecholamines on SPN and which suggest ways in which the catecholamine neurones could regulate the cardiovascular system. Experiments on rats using, intrathecal application of drugs to the spinal cord, iontophoresis, or superfusion of drugs whilst recording either postganglionic nerve activity, extracellularly or intracellularly from SPN respectively, reveal that catecholamines may excite or inhibit SPN. A slow depolarisation is mediated by alpha 1 adrenoceptors whereas alpha 2 adrenoceptors mediate a slow hyperpolarisation. Catecholamines may also excite glycinergic interneurones which elicit fast IPSPs in SPN. By regulating different ionic conductances in the membrane of SPN catecholamines are able to induce SPN to discharge tonically or to oscillate with bursts of action potentials. Furthermore these actions may be modified in the presence of an excitatory amino acid. It is suggested that via these mechanisms differential responses in the sympathetic outflow could be produced.
含有去甲肾上腺素、多巴胺以及可能还有肾上腺素的神经元群投射至脊髓，在那里它们支配交感神经节前神经元（SPN）。本文描述了一些研究，这些研究阐述了儿茶酚胺对SPN的作用，并提出了儿茶酚胺能神经元调节心血管系统的方式。在大鼠身上进行的实验，分别通过向脊髓鞘内给药、离子电泳或药物灌流，同时分别在节后神经活动时从SPN细胞外或细胞内进行记录，结果显示儿茶酚胺可能兴奋或抑制SPN。α1肾上腺素能受体介导缓慢去极化，而α2肾上腺素能受体介导缓慢超极化。儿茶酚胺还可能兴奋甘氨酸能中间神经元，这些中间神经元在SPN中引发快速抑制性突触后电位（IPSP）。通过调节SPN膜中的不同离子电导，儿茶酚胺能够诱导SPN产生紧张性放电或伴随动作电位爆发而振荡。此外，在存在兴奋性氨基酸的情况下，这些作用可能会被改变。有人提出，通过这些机制可能会产生交感神经输出的差异反应。
