Zheng L, Golub A S, Pittman R N
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA.
Am J Physiol. 1996 Jul;271(1 Pt 2):H365-72. doi: 10.1152/ajpheart.1996.271.1.H365.
We have applied the phosphorescence lifetime technique (Vanderkooi, J. M., G. Maniara, T. J. Green, and D. F. Wilson. J. Biol. Chem. 262: 5476-5482, 1987) to determine oxygen tension in single capillaries of the hamster retractor muscle. Palladium meso-tetra(4-carboxyphenyl)porphine (10 mg/ml, pH 7.40, bound to bovine serum albumin) was used as the phosphorescent oxygen sensor. Our measurement system consisted of a microscope configured for epi-illumination, a strobe flash lamp, a 430-nm bandpass excitation filter, and a 630-nm cut-on emission filter. A rectangular diaphragm was used to limit the illumination field to 10 microns x 10 microns, and an end-window photomultiplier tube was used to detect the phosphorescence signal, which was then input to an analog-to-digital board in a personal computer. In vitro calibrations were carried out at 37 degrees C on samples flowing through a glass capillary tube (diameter, 300 microns) at four different O2 concentrations (0, 2.5, 5, and 7.5%). In vivo tests were carried out on arterioles, capillaries, and venules of the retractor muscle of anesthetized hamsters. The phosphorescent compound was administered by injection into a jugular vein (20 mg/kg). Phosphorescence decay curves were analyzed by a new model of heterogeneous oxygen distribution in the excitation/emission volume. Mean Po2 values and the local Po2 gradients within the excitation/ emission volume were calculated from phosphorescence life-times obtained from individual decay curves. The time course of Po2 obtained during 0.5-s measurement periods (5 decay curves at 0.1-s intervals) at a given site along a capillary indicated the presence of a gradient in Po2 within the plasma space between and near red blood cells. Similar Po2 gradients were also detected in arterioles and venules. Mean Po2 values for arterioles, capillaries, and venules over the 0.5-s observation period were 27 +/- 5, 14 +/- 2, and 11 +/- 3 (SD) mmHg, respectively. The magnitude of the Po2 gradient in the arterioles, capillaries, and venules was 6 +/- 1, 4 +/- 1, and 2 +/- 1 mmHg/micron, respectively.
我们应用磷光寿命技术（Vanderkooi, J. M., G. Maniara, T. J. Green, 和 D. F. Wilson. J. Biol. Chem. 262: 5476 - 5482, 1987）来测定仓鼠牵张肌单根毛细血管中的氧张力。钯中-四(4-羧基苯基)卟啉（10 mg/ml，pH 7.40，与牛血清白蛋白结合）用作磷光氧传感器。我们的测量系统由配置用于落射照明的显微镜、频闪闪光灯、430 nm带通激发滤光片和630 nm截止发射滤光片组成。使用矩形光阑将照明场限制为10微米×10微米，并用端窗光电倍增管检测磷光信号，然后将其输入个人计算机中的模数转换板。在37℃下，对流经玻璃毛细管（直径300微米）的样品在四种不同的O2浓度（0、2.5、5和7.5%）下进行体外校准。在麻醉仓鼠的牵张肌的小动脉、毛细血管和小静脉上进行体内测试。通过静脉注射（20 mg/kg）给予磷光化合物。通过激发/发射体积中氧分布不均匀的新模型分析磷光衰减曲线。根据从各个衰减曲线获得的磷光寿命计算激发/发射体积内的平均Po2值和局部Po2梯度。在沿着毛细血管的给定部位，在0.5秒测量期间（以0.1秒间隔的5条衰减曲线）获得的Po2随时间变化的过程表明，在红细胞之间和附近的血浆空间内存在Po2梯度。在小动脉和小静脉中也检测到类似的Po2梯度。在0.5秒观察期内，小动脉、毛细血管和小静脉的平均Po2值分别为27±5、14±2和11±3（标准差）mmHg。小动脉、毛细血管和小静脉中Po2梯度的大小分别为6±1、4±1和2±1 mmHg/微米。
