Variational trend of vascular endothelial growth factor in rat models of lower limb ischemia

Jijuan ZENG; Bohua YANG; Lingqun ZHU; Lina LI; Yufeng LI; Yuan CHEN

ABSTRACT

BACKGROUND:

In the initial stage of ischemia,organisms complete angiogenesis and maintain the blood supply of organization through compensatory regulation and repair,in which process a variety of cytokines,especially vascular endothelial growth factor (VEGF),have played a key role.

OBJECTIVE:

To observe the characteristics and rules of VEGF level changes in both ischemic tissues and blood serums at different time points after establishing rat models of lower limb ischemia.DESIGN,TIME AND

SETTING:

A randomized controlled animal experiment was performed at the Loboratory for Key Subjects in Dongzhimen Hospital and the Laboratory of Molecular Biology in Beijing University of Chinese Medicine from April to November in 2007.MATERIALSA total of 42 male SD rats of 4 weeks were divided by random digits table into 6 groups,namely a control group and a model group which was subdivided into 5 groups at the time points of hour 4,day 3,weeks 1,2 and 4 post modeling respectivly.

METHODS:

Rat models of lower limb ischemia were established in the model group by performing ligation and mutilation operation to left femoral arteries of rats that were anesthetized with 100 g/L chloral hydrate. At the time points of hour 4,day 3,weeks 1,2 and 4 following modeling respectively,rats were selected to extract their abdominal aorta blood samples whose supernatant was then obtained through 10 minutes of 3 000r/min centrifugalization. Gastrocnemius tissues in left legs of rats were isolated at the same time. Samples in control group were obtained directly from anesthetized rats.MAIN OUTCOME

MEASURES:

Western blotting method was used for detecting protein expression of VEGF in ischemic tissues and ELASA method for VEGF level in serum.

RESULTS:

The protein expression of VEGF in ischemic tissues began to increase immediately at hour 4 following ischemia and reached a peak at day 3,after which it reduced gradually till week 2 when it reached its minimum. Then it began to increase again and reached the level close to that of normal tissues by the end of week 4 following ischemia. As for the VEGF level in serum,it decreased immediately after ischemia,with the maximum decrease amplitude between immediate and hour 4 following ischemia,a smaller one between hour 4 and week 1;From week 1 following ischemia on,it began to increase but was still lower than the normal level by the end of week 4 (P＜0.01 ).The VEGF level in serum changed with the tendency of immediate decrease from hour 4,minimum at week 1 and graduate increase after week 1 following ischemia.

CONCLUSION:

After ischemia in lower limb,VEGF level in ischemic tissues changes in the direction of increase-decrease-increase;VEGF level in serum changed in the direction of decrease-increase. In another words,VEGF levels after ischemia shows the characteristics of being low in serum and high in local ischemic tissues.