School of Nursing, The University of Akron, Akron, OH, 44325, USA,
Cell Biochem Biophys. 2013 Nov;67(2):451-9. doi: 10.1007/s12013-013-9611-y.
We noninvasively monitored the partial pressure of oxygen (pO2) in rat's small intestine using a model of chronic mesenteric ischemia by electron paramagnetic resonance oximetry over a 7-day period. The particulate probe lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) was embedded into the oxygen permeable material polydimethyl siloxane by cast-molding and polymerization (Oxy-Chip). A one-time surgical procedure was performed to place the Oxy-Chip on the outer wall of the small intestine (SI). The superior mesenteric artery (SMA) was banded to ~30% of blood flow for experimental rats. Noninvasive measurement of pO2 was performed at the baseline for control rats or immediate post-banding and on days 1, 3, and 7. The SI pO2 for control rats remained stable over the 7-day period. The pO2 on day-7 was 54.5 ± 0.9 mmHg (mean ± SE). SMA-banded rats were significantly different from controls with a noted reduction in pO2 post banding with a progressive decline to a final pO2 of 20.9 ± 4.5 mmHg (mean ± SE; p = 0.02). All SMA-banded rats developed adhesions around the Oxy-Chip, yet remained asymptomatic. The hypoxia marker Hypoxyprobe™ was used to validate the low tissue pO2. Brown cytoplasmic staining was consistent with hypoxia. Mild brown staining was noted predominantly on the villus tips in control animals. SMA-banded rats had an extended region of hypoxic involvement in the villus with a higher intensity of cytoplasmic staining. Deep brown stainings of the enteric nervous system neurons and connective tissue both within layers and in the mesentery were noted. SMA-banded rats with lower pO2 values had a higher intensity of staining. Thus, monitoring SI pO2 using the probe Oxy-Chip provides a valid measure of tissue oxygenation. Tracking pO2 in conditions that produce chronic mesenteric ischemia will contribute to our understanding of intestinal tissue oxygenation and how changes impact symptom evolution and the trajectory of chronic disease.
我们通过电子顺磁共振血氧测定法，在慢性肠系膜缺血模型中，在 7 天的时间内，无创性监测大鼠小肠的氧分压（pO2）。将颗粒探针锂辛氧基萘酞菁（LiNc-BuO）通过铸模和聚合（Oxy-Chip）嵌入到透气材料聚二甲基硅氧烷中。一次性手术将 Oxy-Chip 放置在小肠（SI）的外壁上。肠系膜上动脉（SMA）被捆绑到血流的约 30%，用于实验大鼠。在对照大鼠的基线进行非侵入性 pO2 测量，或在捆绑后立即以及第 1、3 和 7 天进行测量。对照大鼠的 SI pO2 在 7 天的时间内保持稳定。第 7 天的 pO2 为 54.5±0.9mmHg（平均值±SE）。与对照组相比，SMA 结扎大鼠的 pO2 明显降低，结扎后 pO2 迅速下降至最终的 20.9±4.5mmHg（平均值±SE；p=0.02）。所有 SMA 结扎大鼠在 Oxy-Chip 周围都形成了粘连，但仍无症状。缺氧标志物 Hypoxyprobe™ 用于验证组织低氧 pO2。棕色细胞质染色与缺氧一致。在对照动物中，主要在绒毛尖端观察到轻度棕色染色。SMA 结扎大鼠的绒毛中缺氧涉及的区域扩大，细胞质染色强度增加。在肠神经系统神经元和结缔组织的各个层内和肠系膜中都观察到深棕色染色。pO2 值较低的 SMA 结扎大鼠的染色强度较高。因此，使用探头 Oxy-Chip 监测 SI pO2 可提供组织氧合的有效测量。跟踪产生慢性肠系膜缺血的条件下的 pO2 将有助于我们了解肠道组织氧合以及这些变化如何影响症状演变和慢性疾病的轨迹。
