EXCITATION BY IRRITANT CHEMICAL-SUBSTANCES OF SENSORY AFFERENT UNITS IN THE CATS CORNEA
EXCITATION BY IRRITANT CHEMICAL-SUBSTANCES OF SENSORY AFFERENT UNITS IN THE CATS CORNEA
复制标题
DOI：
10.1113/jphysiol.1991.sp018621
复制
发表时间：
1991-06-01
影响因子：
5.5
通讯作者：
REBOLLO, I
中科院分区：
文献类型：
--
作者：
BELMONTE, C;GALLAR, J;REBOLLO, I
1. 在深度麻醉的猫的角膜上，单单位电活动记录了薄的髓鞘感觉神经纤维。根据它们对机械（校准的von Frey毛发）、化学（10 mm -乙酸和/或616 mM-NaCl）和热（冰冷或加热至51℃）刺激的反应，角膜A-delta纤维被分类为多模态伤害感受器（63%）、高阈值机械感受器（22%）和机械-热伤害感受器（15%）。在眼睛边缘发现了只对寒冷有反应的薄髓鞘纤维。在角膜表面施加10毫米醋酸30秒，在多峰纤维中引起脉冲的快速放电，通常随后是低频脉冲活动。NaCl （616 mM）产生了更缓慢和持续的射击反应。多模态纤维对酸的反应与细胞外pH值（pH范围：4.5-6.0）成正比。经过反复加热后，大多数机械热装置对酸性刺激产生了敏感性。外用0.33 mm辣椒素刺激角膜多模伤害感受器；辣椒素作用后5分钟，这些纤维中约有15%在所有后续刺激下失活。在0.33 ~ 3.3 mm辣椒素作用下，其余纤维的化学和热敏性消失，但机械敏性保持不变。角膜机械感受器和唇缘冷感受器不受辣椒素（33 mM）的影响。这些实验表明，猫的角膜受多模性和机械感受性a - δ伤害感受器的支配。在多模伤害性纤维中，机械和化学敏感性似乎是由不同的转导机制提供的。
1. Single-unit electrical activity was recorded from thin myelinated sensory nerve fibres innervating the cornea of deeply anaesthetized cats.2. Based on their responses to mechanical (calibrated von Frey hairs), chemical (10 mM-acetic acid and/or 616 mM-NaCl) and thermal (ice-cold or heat up to 51-degrees-C) stimuli, corneal A-delta fibres were classified as polymodal nociceptors (63%), high-threshold mechanoceptors (22%) and mechano-heat nociceptors (15%). Thin myelinated fibres responding only to cold were found in the limbus of the eye.3. Application of 10 mM-acetic acid on the corneal surface for 30 s evoked in polymodal fibres a brisk discharge of impulses often followed by a low-frequency impulse activity. NaCl (616 mM) produced a more gradual and sustained firing response.4. The responses of polymodal fibres to acid were proportional to extracellular pH values (pH range: 4.5-6.0). After sensitization to repeated heating, most mechano-heat units developed a sensitivity to acidic stimulation.5. Topical 0.33 mM-capsaicin excited polymodal nociceptors of the cornea; 5 min after capsaicin about 15% of these fibres were inactivated to all subsequent stimuli. In the rest of the fibres, chemical and thermal sensitivity disappeared after 0.33-3.3 mM-capsaicin, but mechanosensitivity was preserved.6. Corneal mechanoceptors and limbal cold receptors were not affected by capsaicin (up to 33 mM).7. These experiments demonstrate that the cornea of the cat is innervated by polymodal as well as mechanoceptive A-delta nociceptors. In polymodal nociceptive fibres, mechanical and chemical sensitivities appear to be subserved by separate transduction mechanisms.