Steg P G, Rongione A J, Gal D, DeJesus S T, Clarke R H, Isner J M
Department of Medicine, St. Elizabeth's Hospital, Tufts University School of Medicine, Boston, Massachusetts 02135.
Circulation. 1989 Jul;80(1):189-97. doi: 10.1161/01.cir.80.1.189.
Recent studies have shown that continuous wave laser irradiation induces contraction of vascular smooth muscle, except at powers far below the threshold for tissue ablation. To determine the corresponding effects of pulsed laser irradiation on vascular smooth muscle tone, vascular rings of rabbit thoracic aorta were mounted isometrically with 1 g tension in Krebs-bicarbonate buffer and irradiated with 308 or 351 nm from an excimer laser through a 400-microns optical fiber. A total of 250 exposures were performed with 1-6.5 mJ/pulse (fluence = 0.8-5.5 J/cm2), 10-50 Hz, and cumulative exposures of 10-120 seconds. Excimer laser irradiation in combinations of pulse energy (PE), repetition rate (RR), and cumulative exposure below, at, or above threshold for tissue ablation consistently produced relaxation unassociated with contraction in each of the 250 exposures. For the total 250 exposures, the magnitude of relaxation (reduction in recorded tension, Rmax) was 55 +/- 4% (mean +/- SEM) of maximum vasomotor reactivity recorded in the specimen in response to administration of serotonin. Rmax varied directly with both PE and RR. When PE was increased from 1 to 5 mJ/pulse (n = 13), Rmax increased from 57 +/- 19% to 80 +/- 19% (p less than 0.0001); when RR was increased from 10 to 50 Hz (n = 10), Rmax increased from 27 +/- 8 to 46 +/- 8 (p less than 0.0001). Rmax varied independently of endothelial integrity (assessed anatomically and pharmacologically) and wavelength (308 vs. 351 nm). Simultaneously recorded tissue-temperature profiles disclosed that during pulsed laser irradiation, tissue temperature rise did not exceed 5 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
最近的研究表明，连续波激光照射可诱导血管平滑肌收缩，但功率远低于组织消融阈值时除外。为了确定脉冲激光照射对血管平滑肌张力的相应影响，将兔胸主动脉血管环在含碳酸氢盐的 Krebs 缓冲液中以 1 g 张力等长安装，并用准分子激光通过 400 微米光纤以 308 或 351 nm 波长进行照射。共进行了 250 次照射，脉冲能量为 1 - 6.5 mJ/脉冲（能量密度 = 0.8 - 5.5 J/cm²），重复频率为 10 - 50 Hz，累积照射时间为 10 - 120 秒。在低于、达到或高于组织消融阈值的脉冲能量（PE）、重复频率（RR）和累积照射的组合下，准分子激光照射在 250 次照射中的每一次均始终产生与收缩无关的舒张。在总共 250 次照射中，舒张幅度（记录张力的降低，Rmax）为标本中对血清素给药反应所记录的最大血管运动反应性的 55±4%（平均值±标准误）。Rmax 与 PE 和 RR 均呈直接相关。当 PE 从 1 mJ/脉冲增加到 5 mJ/脉冲（n = 13）时，Rmax 从 57±19%增加到 80±19%（p＜0.0001）；当 RR 从 10 Hz 增加到 50 Hz（n = 10）时，Rmax 从 27±8 增加到 46±8（p＜0.0001）。Rmax 的变化与内皮完整性（通过解剖学和药理学评估）及波长（分别为 308 和 351 nm）无关。同时记录的组织温度曲线显示，在脉冲激光照射期间，组织温度升高不超过 5℃。（摘要截取自 25０ 字）
