Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
Adv Exp Med Biol. 2010;662:157-62. doi: 10.1007/978-1-4419-1241-1_22.
According to the classical concept of Krogh, O(2) is delivered to the tissues solely by capillaries and intra-capillary resistance to O(2) diffusion is negligible. Over the past three decades longitudinal PO(2) and SO(2) gradients in arterioles have been observed with a transmural PO(2) gradient in small arterioles of only 1-2 mmHg. Application of phosphorescence quenching microscopy to measurements of PO(2) in arterioles of the rat mesentery by Tsai et al. (1998) found a large transmural PO(2) in these arterioles. That led to the provocative conclusion that the arteriolar wall is the major sink for O(2) in the microcirculation. Our studies indicate that many of these results can be explained by photo-activated O(2) consumption following phosphor excitation, combined with a large excitation area and high frequency of flash excitation. We have developed the basic principles for phosphorescence quenching microscopy including the need to use a small excitation area, a low excitation frequency and a scanning excitation for stationary samples.
根据克罗格的经典概念，O(2)仅通过毛细血管输送到组织，并且毛细血管内 O(2)扩散的阻力可以忽略不计。在过去的三十年中，人们观察到在小动脉中存在纵向 PO(2)和 SO(2)梯度，而小动脉的壁内 PO(2)梯度仅为 1-2mmHg。蔡等人应用磷光猝灭显微镜对大鼠肠系膜小动脉中的 PO(2)进行测量，发现这些小动脉的壁内 PO(2)很大。这导致了一个有争议的结论，即小动脉壁是微循环中 O(2)的主要消耗部位。我们的研究表明，这些结果中的许多可以通过磷光激发后光激活的 O(2)消耗来解释，同时结合大的激发面积和高频闪光激发。我们已经为磷光猝灭显微镜开发了基本原理，包括需要使用小的激发面积、低的激发频率和用于固定样本的扫描激发。
