Lancaster J R
Department of Physiology, LSU Medical Center, New Orleans, Louisiana 70112, USA.
Nitric Oxide. 1997 Feb;1(1):18-30. doi: 10.1006/niox.1996.0112.
In this review, I consider the quantitative consequences of the diffusion of free NO in determining its biological actions. Several studies have measured the extent to which NO diffuses away from an NO-producing cell, and the distance of its diffusion is quite large, on the order of 100-200 microm. This wide diffusibility is consistent also with the high value for its diffusion constant, 3300 microm2/s. Mathematical simulations based on this wide diffusibility suggest that, within spatial limits of approximately 0.3-0.4 mm, the actions of free NO are dictated by the total number of NO-producing cells within this location as opposed to where the NO-producing cells are located within this space. These results suggest that the actions of NO are surprisingly long range and the diffusion of NO is an important determinant of its biological actions. Thus, the effects of NO on individual target cells may be determined more by each cell's preprogrammed characteristic response to NO than by proximity to an NO source. In addition, scavenging of NO by hemoglobin in blood vessels should represent a significant sink for its scavenging, posing difficulty for the postulate that only free NO functions as EDRF.
在本综述中，我探讨了游离一氧化氮（NO）扩散在决定其生物学作用方面的定量影响。多项研究已测量了NO从产生NO的细胞扩散出去的程度，其扩散距离相当大，约为100 - 200微米。这种广泛的扩散性也与其较高的扩散常数3300微米²/秒相符。基于这种广泛扩散性的数学模拟表明，在大约0.3 - 0.4毫米的空间范围内，游离NO的作用取决于该位置内产生NO的细胞总数，而非这些产生NO的细胞在该空间内的位置。这些结果表明，NO的作用范围惊人地长，且NO的扩散是其生物学作用的一个重要决定因素。因此，NO对单个靶细胞的影响可能更多地取决于每个细胞对NO预先设定的特征性反应，而非与NO源的接近程度。此外，血管中血红蛋白对NO的清除应该是其清除的一个重要途径，这对仅游离NO作为内皮舒张因子（EDRF）发挥作用的假设提出了挑战。
