| Background and AimWith the material and spiritual improvement of living standards, the life's expectancy has improved a lot. Aging is a worldwide trend and can not be shaken. World Health Organization estimates that the proportion of the people over 60 years will grow from 11 % in 2006 to 22 % in 2050. In China, the fifth census showed that people over the age of 60 has reached 130 million, accounting for 10.41 % of the total population, china has been the world's most populous country in old age. The number of the old population over 65 years is 88,110,000; accounting for 6.96 % of the total population, according to the standard structure of the population age, China has entered the ranks of aging countries.Aging particularly is an important risk factor for the cardiovascular disease and a major independent risk factor causes high morbidity and high mortality, which is always along with various diseases. Previous studies have shown that the body can lead to systemic insulin resistance followed by aging. Insulin resistance is closely related to the high incidence of the cardiovascular disease. However, the pathogenesis of insulin resistance has not yet been clarified. In addition, atherosclerosis and the changes of vascular reactivity can also be caused by aging. The understanding of the aging process will improve the quality of life and reduce the incidence of cardiovascular disease significantly. This study was designed to test the characteristic of vascular function and energy metabolism and mitochondrial function in aged rats'thoracic aorta in order to study the development of atherosclerosis and insulin resistance preliminarily, and provide the basis evidence for the clinical prevention and treatment of senile cardiovascular disease.Methods1. Groups of the animal: the experimental animals were divided into two big groups (n=8):①the aging rats (24 months),②the healthy adult rats (5 months).2. The manufacture and testament of the artery rings: take the thoracic aorta from the adult or the aging male SD rats; place it in the pre-cooling K's solution. Separate the connective tissue cleanly from the aorta, cut the aorta into the ring specimens about 2-3mm. Rings will be hang in the K's solution about 8 ml at 37℃, sustain through a mixture of 95 % 02 + 5 % CO2. Connect tension transducer to record changes in vascular ring tension. Balance 1 h, and add Norepinephrine (l mol / l) in order to test the activity of the samples, and then washed to baseline. Stable the samples about 40 min, Start up the experiment. Testament of vascular endothelial function: Determination of blood vessel dilation. If the dilation rate of the aorta is beyond of 80 %, indicating the good integrity of endothelial, and damage of endothelial is small; if the number is less than 30%, indicating the big damage of endothelial and the function is not complete.3. Determination of vascular NO: Take the perfusate of vascular, use the NO kit according to the requirements. Use Griess colorimetric to test the outcome of NO content with NaNO2 as a standard curve, calculating under the spectrophotometer of 540 mm.4. Determination of vascular energy metabolism: test the protein expression of AMPK, evaluating vascular changes of energy metabolism.5. Determination of mitochondrial function: use 782-type oxygen consumption apparatus to measure the mitochondrial oxygen consumption.Results1.The general body weight in the aging rats is heavier than in the adult rats (276±5 vs 775±2 g, n=8, P <0.05) The body weight shows a rapid increase in the adult rats in the course of the experiment, in contrast, the weight in the aging rats is stable.2. After a fasting of 12h, the blood glucose and plasma insulin levels was significantly higher in adult rats than in aging rats {(4.21±0.06 vs 5.70±0.03 mmol / l, n = 8, P <0.05),(14.4±0.2 vs 23.6±0.2 g, n = 8, P <0.05)}. We can see there is systemic insulin resistance in the aging rats.3. The output of NO in endothelial cells shows a significant difference between the adult rats and aging rats (45.33±0.38 vs 9.07±0.15 umol/l, n = 8, P <0.05).4. The expression of protein AMPKα1 is significantly reduced in aging rats comparing to in adult rats (P <0.05). The oxygen consumption of mitochondria shows a significant difference between the adult rats and aging rats (2.42±0.03 vs 1.33±0.33 umol/min/g, n = 8, P <0.05). Conclusion1. Compared with the normal healthy adult rats, the aging rats significantly gained weight, but changed little; both the systolic and diastolic function decreased, including a higher degree of decline in diastolic function.2. Compared with normal healthy adult rats, NO decreased in the aging rats, resulting in a decreased dilation of artery, but the blood glucose and plasma insulin levels were significantly increased.3. Compared with normal healthy adult rats, the expression of AMPK was down in the aging rats main protease, directly affect the systolic and diastolic function of blood vessels.4. Compared with normal healthy adult rats, mitochondrial oxygen consumption capacity decreased in the aging rats, demonstrating a decreased function in mitochondria and resulting in dysfunction of blood vessels.
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