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, 31 (4), 217-221
eCollection

In vivo Assessment of Endothelial Function in Small Animals Using an Infrared Pulse Detector

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In vivo Assessment of Endothelial Function in Small Animals Using an Infrared Pulse Detector

Cyuan-Cin Liu et al. Ci Ji Yi Xue Za Zhi.

Abstract

Objective: Endothelial dysfunction is the earliest change in atherosclerosis. Flow-mediated dilatation (FMD) is used to assess endothelial function in humans. However, this assessment is not easy in small animals. This study demonstrated the reliability and reproducibility of a proposed instrument for in vivo assessment of FMD in a rodent model using infrared pulse sensors.

Materials and methods: We used 24 adult male Wistar Kyoto rats randomly divided into three groups. FMD was measured under continuous infusion of normal saline followed by intra-arterial infusion of acetylcholine (Ach; n = 8), sodium nitroprusside (SNP; n = 8), or Nω-nitro-L-arginine methyl ester (L-NAME; n = 8).

Results: The dilatation indices (DIs) of all three groups were similar before application of the vasoactive agents (1.82 ± 0.46, 1.81 ± 0.44, and 1.93 ± 0.40, P = 0.877, by one-way analysis of variance). The DI was significantly increased during infusion of Ach (2.97 ± 1.03 vs. 1.82 ± 0.46, P = 0.015), unchanged during infusion of SNP (1.81 ± 0.44 vs. 1.98 ± 0.40, P = 0.574), and attenuated during infusion of L-NAME (1.91 ± 0.40 vs. 1.42 ± 0.35; P = 0.028).

Conclusion: The results of this study correlated well with those of human studies, suggesting that this method can be used for in vivo evaluation of endothelial function in small animals.

Keywords: Endothelial function; Flow-mediated dilatation; Nitric oxide.

Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
Setup of the experimental platform. The deep femoral artery was explored at the inguinal area (a) and then connected to an infusion machine with a P10 polyethylene tube (b). An infrared sensor (c) was attached to the footpad of the hind limb and then connected to a signal processing module containing a USB-6009 DAQ card for filtration and digitalization
Figure 2
Figure 2
Anatomic relationship of the arteries used for the hyperemic test at the dissection site. The internal iliac artery was catheterized with a P10 polyethylene tube and connected to an infusion pump for continuous infusion of pharmacological agents. For the hyperemic test, a hemostatic clip was placed at a proximal site on the common iliac artery for transient occlusion of blood flow
Figure 3
Figure 3
(a) The experimental protocol. About 30 min were required for cannulation and acclimatization. Then the animals received a continuous intra-arterial infusion of normal saline until stabilization of the pulse (about 5 min). The baseline pulse amplitude was recorded for 1 min (gray bar), and the common iliac artery was occluded by a hemostatic clip for 5 min (black bar). One minute after releasing the clip, the pulse amplitude was recorded for 1 min (gray bar), and the normal saline infusion was changed to acetylcholine, sodium nitroprusside, or Nω-nitro-L-arginine methyl ester. (b) The dilatation index was defined as the mean 1-min pulse amplitude (period b) 1 min after release of the clip divided by the mean 1-min pulse amplitude (period a) 1 min before occlusion of the left femoral artery
Figure 4
Figure 4
Reproducibility of the measurements was demonstrated by Bland–Altman plotting between the first and second assessments of both hind limbs of five animals at an interval of 1 week
Figure 5
Figure 5
The effects of infusion of different vasoactive agents on the dilatation index (n = 8 in each group). Acetylcholine enhanced dilatation indices significantly (P = 0.015), Nω-nitro-L-arginine methyl ester attenuated dilatation indices (P = 0.028) and sodium nitroprusside did not have a significant effect on the FMD (P = 0.574)

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