Our aim was to quantify and visualize calcium regulating proteins in rat intestine following ischemia-reperfusion injury, as we hypothesized that interstitial and intracellular calcium levels are monitored and modulated in the small intestine via regulation of and by the calcium sensing receptor and possibly stanniocalcin, and that disruption of endothelial calcium cycling following ischemia-reperfusion injury, is offset by increased levels of calcium sensing receptor and stanniocalcin in the submucosa and muscularis externa, allowing for continued support of neuromuscular function and hormone syntheses.  Therefore, sections of rat small intestine were removed from ischemia-reperfused and sham operated animals. Fluorescent probes against the calcium-sensing receptor and stanniocalcin were visualized by fluorescence deconvolution microscopy in sections of jejunum and ileum and localizations and quantities of the proteins were mapped and measured. Ileal samples showed variable, small changes in calcium-sensing receptor protein content following ischemia-reperfusion, while the jejunum demonstrated a significant increase after ischemia-reperfusion injury. This increase in calcium sensing receptor protein was primarily localized to the basal/glandular area of the villi, the submucosa and the serosa of the muscularis externa. A similar pattern of protein increases was seen with stanniocalcin, indicating that ischemia-reperfusion trauma causes regulation of transport mechanisms in an area associated with peri-glandular and submucosal capillaries, suggesting a primary role for calcium regulatory proteins in specific locations of the small intestine, particularly in the jejunum of the proximal small intestine where the majority of digestive product absorption occurs. (236)