| Arterial barorellex (ABR) is an important factor in the homeostatic regulation of the cardiovascular system. The main purpose of this reflex is to maintain blood pressure (BP) within certain limits over a short time period. In mammals, opening of the baroreflex loop leads to a remarkable instability of BP, or a dramatic increase in blood pressure variability (BPV) without a sustained elevation of average blood pressure level during a period of 24 hours. The baroreflex function can be described quantitatively by baroreflex sensitivity (BRS). Recently, baroreflex dysfunction has been found related to many cardiovascular diseases. La Rovere found that BRS was related to sudden death during a period of 2 years after the first attack of acute myocardial infarction. Schwartz testified the similar result in dog model of coronary artery ligation. ABR function has also been found related to the prognosis of chronic heart failure. It is well documented by our previous work that impaired ABR function was significantly related to the end-organ damage in spontaneously hypertensive rat.Atherosclerosis, a disease of the large arteries, is the primary cause of heart disease and stroke. Epidemiological studies have revealed several important environmental and genetic risk factors associated with atherosclerosis, such as hypertension, diabetes mellitus. Moreover, hemodynamic factors such as the influences of shear stress and turbulences on blood vessel, especially on endothelium also play a very important role in the pathogenesis of atherosclerosis. Inflammation participates critically in all phases of the atherosclerotic process. C-reactive protein (CRP) and other inflammatory cytokines have been regarded as risk factors in cardiovascular diseases such as atherosclerosis, also as the markers for the judgment of their prognosis. The expression of intercellular adhesion molecule-1 (ICAM-1) and vascular-cell adhesion molecule-1 (VCAM-1) in endothelial cells and smooth musclecells can be induced by the inflammatory cytokines. Moreover, ICAM-1 and VCAM-1 mediate the adhesion and migration of monocyte, and induce endothelial dysfunction, which promote the progress of atherosclerosis.It has been demonstrated that atherosclerosis can lead to baroreflex dysfunction. A reduced afferent baroreceptor activity in atherosclerotic animals was first described by Angell-James. Vlachakis then suggested that atherosclerosis contribute to the diminished baroreceptor sensitivity in elderly hypertensives. Some other scholars have also found impaired ABR function in atherosclerotic animals. Nevertheless, whether baroreflex dysfunction promotes atherosclerosis or not has not been reported so far. It is well known that rabbit has high blood pressure variability due to relative weak ABR function. Thus, rabbit is seldom used in the study of blood pressure, however, often used as the model of atherosclerosis for its vulnerability to it, which is not only related to some biochemical characteristics but also to its baroreflex function deficit. The present study was designed to demonstrate the correlation between ABR function and atherosclerosis, and testify the hypothesis that arterial baroreflex dysfunction promotes the induction of atherosclerosis.METHODS AND RESULTSExperiment 1: Thirty ten-week-old male SD rats were used in this study. The rats were connected to computerized blood pressure monitoring system in conscious state and the hemodynamic signal was recorded for 3 hours. Then systolic blood pressure (SBP), diastolic blood pressure (DBP), heart period (HP), systolic blood pressure variability (SBPV), diastolic blood pressure variability (DBPV), heart period variability (HPV) and BRS were measured. Four weeks later, the rats were fed a high-cholesterol diet (HCD) for 8 weeks' duration after a bolus intraperitoneal injection of Vitamin D3, (600,000 unit/kg BW) to induce atherosclerosis. The high-cholesterol diet contains 3% cholesterol, 0.5% cholic acid, 0.2% 6-propyl 2-thiouracil, 5% sucrose, 10% lard, and 81.3% regular rat chow. The heart was...
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