el Sayed S O, Dyson M
Tissue Repair Research Unit, U.M.D.S., London, United Kingdom.
Lasers Surg Med. 1996;19(4):433-7. doi: 10.1002/(SICI)1096-9101(1996)19:4<433::AID-LSM8>3.0.CO;2-T.
Mast cell activation by low-level laser therapy (LLLT), leading to degranulation and the release of mediators, may be one of the mechanisms by which LLLT can accelerate tissue repair in mammals. The objective of this work, part of an investigation to determine the optimum parameters for increasing mast cell number and degranulation in injured skin, was to determine the effect of different pulsing frequencies of LLLT.
STUDY DESIGN/MATERIALS AND METHODS: Partial-thickness wounds in anaesthetized adult male Wistar rats were irradiated immediately after injury with monochromatic coherent light (wavelength 820 nm) pulsed at either 2.5, 20, 292, or 20,000 Hz at an average power density of 800 mW/cm2 for 27 seconds; the energy density was 21.6 J/cm2. The effects on mast cell number and degranulation were assessed 2 hours post-treatment by counting the numbers of intact and degranulated mast cells in Carnoy-fixed, toluidine blue-stained, sections of irradiated and sham-irradiated wounds.
The total number of mast cells was increased significantly (P < 0.05) by all the frequencies when compared to the sham-irradiated group, but there was no significant difference between frequencies (P > 0.05). However, although the number of degranulated mast cells was higher in all laser-treated wounds, in comparison with the sham-irradiated group, only the 20 Hz (pulse duration 45 ms) and 292 Hz (pulse duration 3 ms) frequencies were significantly effective (P < 0.05).
Increase in mast cell number is not pulsing frequency dependent, whereas degranulation is.
低强度激光疗法（LLLT）激活肥大细胞，导致其脱颗粒并释放介质，这可能是LLLT促进哺乳动物组织修复的机制之一。本研究作为确定增加受损皮肤中肥大细胞数量和脱颗粒的最佳参数研究的一部分，其目的是确定不同脉冲频率的LLLT的效果。
研究设计/材料与方法：对麻醉的成年雄性Wistar大鼠造成部分厚度的伤口，受伤后立即用波长820nm的单色相干光进行照射，脉冲频率分别为2.5、20、292或20000Hz，平均功率密度为800mW/cm²，照射27秒；能量密度为21.6J/cm²。在治疗后2小时，通过计数卡诺固定、甲苯胺蓝染色的照射伤口和假照射伤口切片中完整和脱颗粒的肥大细胞数量，评估对肥大细胞数量和脱颗粒的影响。
与假照射组相比，所有频率照射后肥大细胞总数均显著增加（P<0.05），但各频率之间无显著差异（P>0.05）。然而，尽管所有激光治疗伤口中脱颗粒肥大细胞的数量均高于假照射组，但只有20Hz（脉冲持续时间45ms）和292Hz（脉冲持续时间3ms）频率具有显著效果（P<0.05）。
肥大细胞数量的增加不依赖于脉冲频率，而脱颗粒则依赖于脉冲频率。
