Evidence for two different heat transduction mechanisms in nociceptive primary afferents innervating monkey skin.
Evidence for two different heat transduction mechanisms in nociceptive primary afferents innervating monkey skin.
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DOI：
10.1113/jphysiol.1995.sp020619
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发表时间：
1995-03
期刊：
影响因子：
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通讯作者：
R. Treede;R. Meyer;S. Raja;J. Campbell
中科院分区：
文献类型：
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作者：
R. Treede;R. Meyer;S. Raja;J. Campbell
1. 用激光热刺激器（0.1 s 上升时间，7.5 毫米直径）。 2.在毛状皮肤AMH中观察到两种类型的热反应。 I 型 AMH 在刺激结束时具有峰值放电，对热的响应延迟长达几秒，中位热阈值大于 53 摄氏度，平均传导速度为 25 m s-1 (n = 33)。 II 型 AMH 在 1-3 秒内出现峰值放电，平均响应潜伏期为 120 毫秒，中位热阈值为 46 摄氏度，平均传导速度为 15 米秒-1 (n = 13)。 I 型 AMH 纤维对热敏感，而 II 型 AMH 纤维的热反应在强烈的热刺激后受到抑制。 3.在无毛皮肤中，仅发现I型AMH。 II 型 AMH 的缺乏与无毛皮肤首次出现发热疼痛的情况一致。 4.毛状皮肤中的C纤维伤害感受器在刺激开始时有峰值放电，平均反应潜伏期为100毫秒，中位热阈值为41℃。无毛皮肤中CMH的热响应与毛状皮肤中的热响应没有显着差异。 5. 只有 II 型 AMH 的反应潜伏期足够短，足以解释先痛后热的情况。 II 型 AMH 的热阈值显着高于 CMH。 6. 这些结果表明伤害性传入中存在两种不同的热传导机制。其一，热能迅速转化为动作电位，刺激开始后很快就达到峰值放电。另一方面，热传导明显较慢，峰值放电发生在刺激结束时。化学介导的致敏可能涉及第二种转导机制。
1. Mechano‐ and heat‐sensitive A fibre nociceptors (AMHs) and C fibre nociceptors (CMHs) in hairy skin (forty‐six AMHs and twenty‐one CMHs) and in glabrous skin (fifty‐nine AMHs and ten CMHs) of anaesthetized monkeys were tested with a 30 s, 53 degrees C heat stimulus, delivered by a laser thermal stimulator (0.1 s rise time, 7.5 mm diameter). 2. Two types of heat response were observed in hairy skin AMHs. Type I AMHs had a peak discharge towards the end of the stimulus, response latencies to heat of up to several seconds, a median heat threshold greater than 53 degrees C, and a mean conduction velocity of 25 m s‐1 (n = 33). Type II AMHs had a peak discharge within 1‐3 s, a mean response latency of 120 ms, a median heat threshold of 46 degrees C, and a mean conduction velocity of 15 m s‐1 (n = 13). Type I AMH fibres were sensitized to heat, whereas heat responses of type II AMHs were suppressed following the intense heat stimulus. 3. In glabrous skin, only type I AMHs were found. The absence of type II AMHs is consistent with the absence of first pain to heat in glabrous skin. 4. C fibre nociceptors in hairy skin had a peak discharge near stimulus onset, a mean response latency of 100 ms and a median heat threshold of 41 degrees C. Heat responses of CMHs in glabrous skin were not significantly different from those in hairy skin. 5. Only type II AMHs had response latencies that were short enough to explain first pain to heat. Heat thresholds of type II AMHs were significantly higher than those of CMHs. 6. These results suggest two different heat transduction mechanisms in nociceptive afferents. For one, heat energy is quickly transduced into action potentials, and the peak discharge is reached soon after stimulus onset. For the other, the transduction of heat is distinctly slower, and the peak discharge occurs near the end of the stimulus. Chemically mediated sensitization may be involved in the second transduction mechanism.