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Abstract
Purpose
Rodent models that mimic human renal diseases are being increasingly recognized as powerful tools in the development of new drugs and for evaluating the efficacy of novel therapeutics in a preclinical setting. However, there are few reports on microvasculature imaging of the urinary system in small animals. An experimental study was performed to evaluate the microvasculature in a rat kidney using micro-computed tomography (CT) with three-dimensional images.
Materials and Methods
Five Sprague-Dawley male rats (age: 10-12 weeks, weight: 200-250g) underwent a laparotomy under anesthesia with an intramuscular injection of 0.5cc xylazine hydrochloride and ketamine mixed solution (1:10). After ligation of the abdominal aorta and inferior vena cava immediately above the renal artery, a 24 gazed catheter was inserted into the abdominal aorta. A physiological solution and heparin (500U) were infused through the catheter to flush the blood from the renal vasculature. The kidney was enhanced using self-made contrast material. The excised kidney was frozen for the micro-CT scan.
Results
The mean longitudinal diameter and weight of the 10 resected kidneys was 1.95±0.15cm and 2.0±0.28g, respectively. The images were represented by three-dimensional arrays of cubic voxels with opacities in the blood vessels. In the section taken from the arrays, four regions of the kidney could be identified easily by their characteristic vascular features.
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Fig. 1.
Photograph of the developed micro-computed tomography system for in vivo small animal imaging.
Fig. 2.
The preparation steps for micro-computed tomography (CT) scanning. (A) Laparotomy was performed after anesthesia by an intramuscular injection of 0.5cc xylazine hydrochloride and ketamine mixed solution (1:10). (B) After the ligation of the abdominal aorta and inferior vena cava immediately above the renal artery, a 24 gauged catheter was inserted into the abdominal aorta at 1cm below to the renal artery. (C) A physiologic solution (10cc) and heparin (500U) were infused through the catheter to flush the blood from the renal vasculature. (D) The colors of the kidneys were changed because of the fixation with the contrast material, gelatin and barium sulfate (BaSO4). (E) The excised kidney was frozen for the micro-CT scan.
Fig. 3.
Coronal (A), sagittal (B), and transverse (C) sections through a volume image of a rat kidney. The cortex (Cort), outer stripe of the outer medulla (OSOM), inner stripe of outer medulla (ISOM), and the inner medulla (IM) were distinguished by their vascular features. Interlobar vessels (*) are evident in the sections.
Fig. 4.
Renal microvasculature images of the ex-vivo mouse in the micro-computed tomography (CT). (A) projection image, (B) 3 dimensional-CT reconstruction image.
Table 1.
Characteristics of micro-computed tomography
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