Noninvasive Monitoring of Small Intestinal Oxygen in a Rat Model of Chronic Mesenteric Ischemia

作者：Fisher Elaine M^*; Khan Mahmood; Sali**ury Ronald; Kuppusamy Periannan

来源：Cell Biochemistry and Biophysics, 2013, 67(2): 451-459.

DOI：10.1007/s12013-013-9611-y

• LiNc-BuO
• EPR oximetry
• Intestinal oxygenation
• Superior mesentery artery occlusion
• Chronic mesenteric ischemia

We noninvasively monitored the partial pressure of oxygen (pO(2)) in rat%26apos;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 pO(2) was performed at the baseline for control rats or immediate post-banding and on days 1, 3, and 7. The SI pO(2) for control rats remained stable over the 7-day period. The pO(2) on day-7 was 54.5 +/- A 0.9 mmHg (mean +/- A SE). SMA-banded rats were significantly different from controls with a noted reduction in pO(2) post banding with a progressive decline to a final pO(2) of 20.9 +/- A 4.5 mmHg (mean +/- A SE; p = 0.02). All SMA-banded rats developed adhesions around the Oxy-Chip, yet remained asymptomatic. The hypoxia marker Hypoxyprobe (TM) was used to validate the low tissue pO(2). 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 pO(2) values had a higher intensity of staining. Thus, monitoring SI pO(2) using the probe Oxy-Chip provides a valid measure of tissue oxygenation. Tracking pO(2) 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.

• 出版日期2013-11