Abstract
Despite the importance of translational medicine in cardiovascular research, rat vascular endothelial function and sympathetic activity assessment remains challenging. This study consisted of two parts: part A examined the consistency of reactive hyperemia-elicited dilatation index (DI) before (DIOriginal) and after (DIEEMD) ensemble empirical mode decomposition (EEMD) using Wistar-Kyoto (WKY) rats (n=7). Part B compared the endothelial function and heart rate variability of normal WKY rats (group 1, n=9) with those of spontaneously hypertensive rats (group 2, n=9) at two time points of development. The SD1/SD2 ratio (SSR) was obtained from Poincaré plot analysis to evaluate sympathetic activities. Using a Bland-Altman plot, part A of the study demonstrated a lower agreement of DIOriginal than that of DIEEMD. In part B, despite no significant difference in DIEEMD between the two groups at age 10 weeks, DIEEMD was higher in group 1 (2.25±0.63 vs. 1.43±0.41 for groups 1 and 2, respectively, p=0.004) at 20 weeks. Although no notable change in SSR existed in group 1 between the two time points, a significant difference existed in group 2 (p<0.001). In conclusion, using algorithms of Poincaré plot analysis and EEMD, the impact of age and hypertension on rat vascular endothelial function and heart rate variability can be reliably assessed.
A tribute is paid to Mr. Shih-Syong Dai, who is the research assistant at Buddhist Tzu Chi General Hospital, for performing the animal operations in this study. We are also grateful to Texas Instruments, Taiwan, for providing us with the low-power amplifier in this study. This research was partly supported by the National Science Council under grants NSC 100-2221-E-259-030-MY2 and NSC 100-2221-E-303 -001, Taiwan, Republic of China.
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