DIFFERENCES BETWEEN MAMMALIAN VENTRAL AND DORSAL SPINAL ROOTS IN RESPONSE TO BLOCKADE OF POTASSIUM CHANNELS DURING MATURATION
DIFFERENCES BETWEEN MAMMALIAN VENTRAL AND DORSAL SPINAL ROOTS IN RESPONSE TO BLOCKADE OF POTASSIUM CHANNELS DURING MATURATION
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DOI：
10.1098/rspb.1985.0037
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发表时间：
1985-01-01
期刊：
影响因子：
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通讯作者：
WAXMAN, SG
中科院分区：
文献类型：
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作者：
BOWE, CM;KOCSIS, JD;WAXMAN, SG
在两栖动物中，运动和感觉纤维之间钾通道组织的差异已经被描述过，但以前没有在哺乳动物中进行过研究。在本研究中，我们研究了在大鼠脊髓前根和背根成熟过程中，药物阻断钾传导后的整个神经和单个轴突的反应。我们的研究结果表明，在成熟的哺乳动物的运动和感觉纤维，这是最明显的年轻的根不同的敏感性。 具体而言，4-氨基吡啶（4-AP）的应用导致腹根中的复合动作电位的加宽，这与单纤维的个体动作电位的延迟复极相关。与此相反，年轻的背根钾通道的封锁结果在一个晚负性的复合反应，这是与多峰爆发活动记录从单一的感觉纤维。4-AP对前根纤维的作用在成熟过程中比4-AP对背根纤维的作用更早地减弱。这些结果表明，在哺乳动物的运动和感觉轴突的钾通道的功能组织的发育差异，这可能有影响这两类轴突之间的编码特性的差异。
Differences in potassium channel organization between motor and sensory fibers have been described in amphibians but have not previously been examined in mammals. In the present investigation, we studied whole nerve and single axon responses following pharmacological blockade of potassium conductance in rat ventral and dorsal spinal roots during maturation. Our results indicate a differential sensitivity in maturing mammalian motor and sensory fibers which is most apparent in younger roots. Specifically, application of 4-aminopyridine (4-AP) results in a broadening of the compound action potential in ventral roots which is associated with a delayed repolarization of the individual action potential of single fibers. In contrast, blockade of potassium channels in young dorsal roots results in a late negativity in the compound response which is correlated with multispike bursting activity recorded from single sensory fibers. The effects of 4-AP on ventral root fibers diminish earlier in the course of maturation than do the effects of 4-AP in dorsal root fibers. These results demonstrate developmental differences in the functional organization of potassium channels in mammalian motor and sensory axons which may have implications for differences in coding properties between these two classes of axons.