Department of Surgery, Trauma Center, University Hospital Bergmannsheil, Bochum, Germany.
J Surg Res. 2010 Nov;164(1):169-74. doi: 10.1016/j.jss.2009.07.032. Epub 2009 Aug 5.
The NO/cGMP pathway plays a crucial role in regulation of tissue perfusion. However, a NO-induced desensitization of cGMP-mediated relaxation has been reported in isolated tissue. To examine whether a similar phenomenon can be detected in vivo, we analyzed relaxations of microvessels in response to repeated applications of NO.
The investigations were performed by means of dynamic intravital fluorescence microscopy in the dorsal skinfold chamber of female balb/mice. First, the microvasculature was maximally preconstricted by the application of the vasoconstrictor 5-hydroxytryptamine. Subsequently, relaxation was induced by applying an NO-donator, the S-nitrosoglutathione, to the contracted vessels. Following buffer exchange, constriction and relaxation were repeated. Drugs were given topically into the chamber, directly onto the skin muscle. The response of arterioles to topical administration of vasoactive drugs was determined as the change of the diameter, and quantified using standard software.
The relaxation of arterioles was reduced after repetitive application. The short pretreatment with NO-donor entailed a reduced relaxation of arterioles in response to following application. The absolute change in vessel diameter induced by S-nitrosoglutathione was significantly reduced from 21 μm to 16 μm after the first and the second application, respectively. However, the data also revealed a noticeable reduction of the constricting activity of 5-hydroxytryptamine during the second application, indicating a possible desensitization of the 5-hydroxytryptamine response or a humoral and/or neuronal compensatory mechanisms.
The NO-induced cGMP-mediated relaxation of microvessels was quantified, and the phenomenon of desensitization visualized in vivo by means of dynamic fluorescence microscopy.
NO/cGMP 途径在调节组织灌注中起着至关重要的作用。然而，在分离的组织中已经报道了 NO 诱导的 cGMP 介导的松弛作用脱敏。为了检查在体内是否可以检测到类似的现象，我们分析了对 NO 的重复应用的微血管舒张。
通过在雌性 Balb/c 小鼠的背部皮肤囊室中的动态活体荧光显微镜进行了研究。首先，通过应用血管收缩剂 5-羟色胺使微血管最大程度地预收缩。随后，将 NO 供体 S-亚硝基谷胱甘肽应用于收缩的血管以诱导松弛。缓冲液交换后，重复收缩和松弛。药物通过局部给药到室中，直接涂在皮肤肌肉上。使用标准软件确定了血管活性药物局部给药对小动脉的反应，即直径的变化。
重复应用后，小动脉的舒张减少。NO 供体的短预处理导致随后应用时小动脉舒张减少。S-亚硝基谷胱甘肽诱导的血管直径的绝对变化从第一次应用时的 21μm 显著减少到第二次应用时的 16μm。然而，数据还表明 5-羟色胺的收缩活性在第二次应用期间明显降低，表明可能发生了 5-羟色胺反应的脱敏或体液和/或神经元补偿机制。
通过动态荧光显微镜，对微血管的 NO 诱导的 cGMP 介导的松弛进行了量化，并在体内可视化了脱敏现象。
