Pulsed dye lasers are used effectively in the treatment of psoriasis with long remission time and limited side effects. It is, however, not completely understood which biological processes underlie its favorable outcome. Pulsed dye laser treatment at 585-595 nm targets hemoglobin in the blood, inducing local hyperthermia in surrounding blood vessels and adjacent tissues. While the impact of destructive temperatures on blood vessels has been well studied, the effects of lower temperatures on the function of several cell types within the blood vessel wall and its periphery are not known. The aim of our study is to assess the functionality of isolated blood vessels after exposure to moderate hyperthermia (45 to 60°C) by evaluating the function of endothelial cells, smooth muscle cells, and vascular nerves. We measured blood vessel functionality of rat mesenteric arteries (n=19) by measuring vascular contraction and relaxation before and after heating vessels in a wire myograph. To this end, we elicited vascular contraction by addition of either high potassium solution or the thromboxane analogue U46619 to stimulate smooth muscle cells, and electrical field stimulation (EFS) to stimulate nerves. For measurement of endothelium-dependent relaxation, we used methacholine. Each vessel was exposed to one temperature in the range of 45-60°C for 30 seconds and a relative change in functional response after hyperthermia was determined by comparison with the response per stimulus before heating. Non-linear regression was used to fit our dataset to obtain the temperature needed to reduce blood vessel function by 50% (Half maximal effective temperature, ET50). Our findings demonstrate a substantial decrease in relative functional response for all three cell types following exposure to 55°C-60°C. There was no significant difference between the ET50 values of the different cell types, which was between 55.9°C and 56.9°C (P>0.05). Our data show that blood vessel functionality decreases significantly when exposed to temperatures between 55°C-60°C for 30 seconds. The results show functionality of endothelial cells, smooth muscle cells, and vascular nerves is similarly impaired. These results help to understand the biological effects of hyperthermia and may aid in tailoring laser and light strategies for selective photothermolysis that contribute to disease modification of psoriasis after pulsed dye laser treatment.

脉冲染料激光可有效治疗牛皮癣，缓解时间长且副作用有限。然而，尚不完全了解哪些生物过程是其有利结果的基础。 585-595 nm 的脉冲染料激光治疗针对血液中的血红蛋白，引起周围血管和邻近组织的局部高温。虽然破坏性温度对血管的影响已得到充分研究，但较低温度对血管壁及其周围几种细胞类型功能的影响尚不清楚。我们研究的目的是通过评估内皮细胞、平滑肌细胞和血管神经的功能来评估暴露于中度高温（45 至 60°C）后的离体血管的功能。我们通过测量钢丝肌动描记器加热血管前后的血管收缩和舒张来测量大鼠肠系膜动脉（ n = 19）的血管功能。为此，我们通过添加高钾溶液或血栓素类似物 U46619 来刺激平滑肌细胞，并通过电场刺激 (EFS) 来刺激神经，从而引起血管收缩。为了测量内皮依赖性松弛，我们使用乙酰甲胆碱。每个容器暴露在 45-60°C 范围内的一个温度下 30 秒，通过与加热前每次刺激的反应进行比较，确定热疗后功能反应的相对变化。使用非线性回归来拟合我们的数据集，以获得使血管功能降低 50% 所需的温度（半最大有效温度，ET50）。我们的研究结果表明，暴露于 55°C-60°C 后，所有三种细胞类型的相对功能反应均大幅下降。不同细胞类型的ET50值在55.9℃~56.9℃之间无显着性差异（P >0.05）。我们的数据显示，当暴露在 55°C-60°C 的温度下 30 秒时，血管功能会显着下降。结果表明，内皮细胞、平滑肌细胞和血管神经的功能也同样受到损害。这些结果有助于了解热疗的生物学效应，并可能有助于定制选择性光热作用的激光和光策略，从而有助于脉冲染料激光治疗后银屑病的疾病缓解。