texas-red and Ischemia

Glomerular filtration rate (GFR), which measures the amount of plasma filtered through the kidney within a given time, is an essential and clinically important indicator of kidney function. Here, we report a new ratiometric measurement technique based on intravital fluorescence microscopy that allows rapid evaluations of renal function in rodent models. By using this technique, plasma clearance rates of a fluorescent GFR marker can be measured in less than 5 min following a bolus infusion of a fluorescent dye mixture into the bloodstream. The plasma clearance kinetics of the GFR marker showed consistent values when measured in healthy animals at locations both in the kidney and from the skin. In addition, by using this technique, we were able to rapidly determine renal function with acute renal failure animal models and with other animal models where kidney filtration functions were altered. The measured plasma clearance kinetics using this technique correlated with expected changes in kidney function. We found this ratiometric approach offers improved accuracy and speed for quantifying renal function compared with the approach using single fluorescent probes, and the measurement can be done noninvasively from the skin. This approach also offers a high sensitivity for determining plasma clearance rate of a fluorescent compound. This feature is important for rapidly quantifying small differences in plasma clearance when kidney function is changing.

Topics: Algorithms; Animals; Dextrans; Diagnostic Imaging; Fluorescein-5-isothiocyanate; Fluorescent Dyes; Glomerular Filtration Rate; Image Processing, Computer-Assisted; Insulin; Ischemia; Kidney; Kinetics; Ligation; Male; Microscopy, Fluorescence; Nephrectomy; Plasma; Rats; Rats, Sprague-Dawley; Regional Blood Flow; Renal Circulation; Skin; Xanthenes

Fluorescently labeled albumin is used frequently as a tracer when monitoring microvascular permeability. Several fluorescent dyes are available for labeling protein, including fluorescein isothiocyanate (FITC) and Texas Red (TR). Because differences in leakage of dye-labeled proteins have been reported, the objective of the present study was to compare the accumulation of these two tracers in interstitium and lymph after the inflammatory event of ischemia-reperfusion.. Anesthetized rats were injected intravenously with FITC-labeled albumin (FITC-alb) and TR-labeled albumin (TR-alb) before 30 minutes of mesenteric ischemia. Because the tracers leaked out of the microcirculation after reperfusion, accumulation in the surrounding buffer-superfused tissue, and in separate experiments, accumulation in lymph vessels, was defined as the ratio of tissue-to-plasma and lymph-to-plasma fluorescence.. Reperfusion induced a significant increase in tissue-to-plasma fluorescence of FITC-alb; however, no increase was observed for TR-alb. In contrast, lymph-to-plasma fluorescence of TR-alb tended to be greater than FITC-alb. Reperfusion-induced increases in tissue-to-plasma fluorescence of TR-alb occurred only when the superfusate was replaced with mineral oil, in which case tissue-to-plasma TR-alb fluorescence tended to be greater than FITC-alb.. Measurement of fluorescently labeled albumin leakage from mesenteric venules depends on the dye used to label the albumin and requires an assessment of losses from the extravascular measuring region.

Topics: Albumins; Animals; Biological Transport; Capillary Permeability; Emollients; Fluorescein-5-isothiocyanate; Fluorescent Dyes; Ischemia; Lymph; Male; Mesentery; Mineral Oil; Perfusion; Rats; Rats, Inbred F344; Reperfusion Injury; Xanthenes