Myelinated mechanically insensitive afferents from monkey hairy skin: Heat-response properties
Myelinated mechanically insensitive afferents from monkey hairy skin: Heat-response properties
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DOI：
10.1152/jn.1998.80.3.1082
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发表时间：
1998-09-01
影响因子：
2.5
通讯作者：
Campbell, JN
中科院分区：
文献类型：
--
作者：
Treede, RD;Meyer, RA;Campbell, JN
为了比较机械敏感性和机械不敏感性A纤维伤害感受器的热反应，使用电搜索技术来定位在麻醉猴中支配多毛皮肤的156个A纤维（77个A β纤维，79个A δ纤维）的感受野。三分之二的这些传入要么是低阈值机械感受器（n = 91）或低阈值冷感受器（n = 11）。9个A β纤维和41个A δ纤维是皮肤伤害性感受器，4个AS纤维支配皮下组织。大多数皮肤A-纤维伤害感受器是热敏感的（43/50 = 86%）。热不敏感的皮肤A纤维伤害性感受器由一个冷伤害性感受器和三个沉默伤害性感受器组成。和三个高阈值机械感受器两种类型的反应，观察到一个强烈的热刺激（53度，30秒）。I型（IZ = 26）的特点是潜伏期长（平均：5 s）和晚峰放电（16 s）。Ⅱ型（n = 17）的特点是潜伏期短（0.2 a），峰早（0.5 s）;与IT型纤维相比，I型纤维表现出更快的传导速度（25与14 m/s）和更高的听觉阈值（>53与47 ℃，1-s持续时间）。I型热反应是致敏的结果的可能性在三种纤维中通过确定对30秒持续时间刺激（42-46摄氏度）的热阈值来测试。对于这种长刺激持续时间，热阈值在多次运行中是可重现的，并且这些测试不会改变1-s持续时间刺激的阈值。因此，具有I型热反应的纤维不是通过敏化产生热反应的高阈值机械感受器。具有II型热反应的纤维具有比具有I型热反应的纤维（5巴）显著更高的机械阈值（中值：15巴）。这一发现解释了在早期研究中很少观察到TI型热反应的观察结果，其中搜索技术依赖于机械反应。具有II型反应的纤维表现出对热刺激的分级反应，对重复应用听觉刺激的明显疲劳，以及对持续热刺激的适应，类似于在C-纤维伤害感受器中所见。对热的第一疼痛感觉由机械不敏感的LIA型纤维伤害感受器提供。I型A-纤维伤害感受器可能向长持续时间的听觉刺激发出疼痛信号，并且可能向机械刺激发出第一疼痛感觉信号。
To compare the heat responses of mechanically sensitive and mechanically insensitive A-fiber nociceptors, an electrical search technique was used to locate the receptive fields of 156 A fibers that innervated the hairy skin in the anesthetized monkey (77 A beta-fibers, 79 A delta-fibers). Two-thirds of these afferents were either low-threshold mechanoreceptors (n = 91) or low-threshold cold receptors (n = 11). Nine A beta-fibers and 41 A delta-fibers were cutaneous nociceptors, and four AS-fibers innervated subcutaneous tissue. The majority of cutaneous A-fiber nociceptors were heat sensitive (43/50 = 86%). Heat-insensitive cutaneous A-fiber nociceptors consisted of one cold nociceptor, three silent nociceptors. and three high-threshold mechanoreceptors. Two types of response were observed to an intense heat stimulus (53 degrees, 30 s). Type I (IZ = 26) was characterized by a long latency (mean: 5 s) and a late peak discharge (16 s). Type II (n = 17) was characterized by a short latency (0.2 a) and an early peal; discharge (0.5 s). Type I fibers exhibited faster conduction velocities (25 vs. 14 m/s) and higher hear thresholds ( >53 vs. 47 degrees C, 1-s duration) than type IT fibers. The possibility that the type I heat response was a result of sensitization was tested in three fibers by determining the heat threshold to 30-s duration stimuli (42-46 degrees C). For this long stimulus duration heat thresholds were reproducible across multiple runs, and the threshold to the 1-s duration stimulus was not altered by these tests. Thus fibers with a type I heat response were not high-threshold mechanoreceptors that developed a heat response through sensitization Fibers with a type II heat response had significantly higher mechanical thresholds (median: 15 bar) than fibers with a type I heal response (5 bar). This finding accounts For the observation that type TI heat responses were infrequently observed in earlier studies wherein the search technique depended on mechanical responsiveness. Fibers with a type II response exhibited a graded response to heat stimuli, marked fatigue to repeated applications of hear stimuli, and adaptation to sustained heat stimuli similar to that seen in C-fiber nociceptors. First pain sensation to heat is served by type LI A-fiber nociceptors that are mechanically insensitive. Type I A-fiber nociceptors likely signal pain to long-duration hear stimuli and may signal first pain sensation to mechanical stimuli.