重组人生长激素对急性心肌梗死大鼠心肌血管生成的影响

Effect of rh-GH on myocardial angiogenesis of rats with acute myocardial infarction

目的探讨肌肉注射重组人生长激素(rhGH)对急性心肌梗死(AMI)大鼠心肌血管生成及相关生长因子———血管内皮细胞生长因子(VEGF)、碱性成纤维细胞生长因子(bFGF)的影响。方法50只Wistar大鼠经10%戊巴比妥钠麻醉后开胸,剪开心包腔,做左冠状动脉前降支结扎术致其发生AMI,术后24h存活者37只被随机分为rhGH治疗组(19只)和对照组(18只)。治疗组以rhGH0.25U(kg·d)×3周肌注,对照组予同等容积的生理盐水肌注,3周后处死大鼠,开胸经升主动脉向冠状动脉内灌注10%甲醛20～30min固定心脏,心脏标本经切片处理。分别测定血浆和心肌的VEGF、bFGF的量及左心室梗死区周围毛细血管密度。结果(1)治疗组与对照组在AMI后3周其血浆bFGF、VEGF浓度均较实验开始时明显增加。治疗组较对照组升高更加显著,分别为69±5vs36±4(P<0.05)和47±5vs32±6(P<0.05)。(2)大鼠心肌内bFGF及VEGF治疗组均较对照组高,分别为79±7vs31±3(P<0.01)和72±7vs39±7(P<0.01)。(3)血浆bFGF、VEGF的浓度与梗死区周围心肌内毛细血管密度呈正相关(r分别为0.91和0.86,P<0.001),其回归方程分别为:毛细血管数=1.85bFGF-18.526;毛细血管数=1.249VEGF+6.127。结论rhGH促进AMI大鼠心肌细胞生长因子bFGF和VEGF的表达和分泌,提高缺血心肌局部及血液中bFGF和VEGF的浓度,促进梗死区周围毛细血管的生成。

Objective To determine the effect of intramuscular administration of rh-GH on myocardial angiogenesis and the expression of bFGF, VEGF in rats with acute myocardial infarction. Methods Left anterior descending coronary arteries have been ligated in 50 Wistar rats after anesthesia by 10% pentobarbital sodium. 37 rats with AMI survived after the operation. The rats are randomized into rh-GH treatment group （ n = 19） and the control group （ n = 18）. Treatment group is given rh-GH 0.25 U/kg·d im for three weeks while the control group is given NS im at the same time. All the 37 rats are killed after 3 weeks and the heart specimen were fixed by injecting 10% formalin from the ascending aorta into the coronary arteries. The level of VEGF and bFGF in blood plasma and myocardium as well as the density of newly formed vessels in the peri-infactional area were measured separately. Plasma VEGF and bFGF were measured before experiment and 3 weeks after experiment by enzymelabel method, bFGF and VEGF in myocardiun were semi-quaot fixed by imaging after SP inmuno-histochemical stain. Left ventricle capillary density： 3 angiogenesis sites was identified by 40 × or 100 × microscopy. F8 labelled microvessels were measured averagely under 200 × microscope. Results （ 1 ） Plasma VEGF and bFGF in both groups were elevated, and elevation of the treatment group was more remarkable than the control group 69 ± 5 vs 36±4 （P〈0.05） and 47 ±5 vs 32±6 （P〈0.05） respectively. （2） The level of myocarium bFGF and VEGF of the treatment group was higher than that in the control group, 79 ± 7 vs 31 ± 3 （ P 〈 0.01 ） and 72 ± 7 vs 39 ± 7 （ P 〈 0.01 ） respectively. The density of neovascularization in the treatment group was righer than that in the control group （51 ± 6 vs 28 ± 3, P 〈 0.01 ）. （3） Plasma bFGF and VEGF were both positively correlated with peri-infarctional myocardium capillary density （ correlation coefficient are 0.91 and 0.86, P 〈 0.01 respectively）. The regression equations were capillary = 1. 249 VEGF ＋ 6.127 and capillary = 1.85 bFGF - 18.526, respectively.Conclusion rh-GH can increase the expression and excretion of myocardial growth factors VEGF and bFGF, increare VEGF and bI：GF content in both ischemic myocardium and systemic circulation, and promote myocardial angiogenesis.