Ghrelin注射对大鼠血压和心肌收缩功能的影响

目的: 探讨促生长激素释放多肽(ghrelin,GRL)对大鼠心血管功能的影响及其意义。方法: 将40只成年雄性SD大鼠分为对照组和4个剂量的GRL组,静脉注射GRL后测量血流动力学指标。随后采用单细胞动态边缘检测系统测定细胞收缩功能的变化。结果: ①GRL各组平均动脉血压（MABP）较对照组明显下降（P<0.05）。②GRL各组单个心肌细胞收缩功能指标最大收缩幅度（PTA）、最大缩短和复长速率（±dL/dtmax）较对照组明显降低（P<0.05）。结论: GRL可剂量依赖性地降低大鼠的MABP,降低心肌细胞的收缩功能。

Effects of intravenous injection of ghrelin on blood pressure and cardiac contractility in rats

AIM: To investigate the effect of ghrelin on the cardiovascular system. METHODS: 40 male Sprague-Dawley (SD) rats were randomized into control group and four drug groups with five rats in each group. After the rats were anesthetized, a microcatheter was inserted into the left ventricle through the right carotid artery, and left ventricular developed pressure (LVDP), maximal velocity of left ventricular pressure development and decline (+LV dP/dtmax and -LV dp/dtmax) and heart rate (HR) were recorded by a biological signal collecting system. Simultaneously, mean arterial blood pressure (MABP) was measured by right femoral artery intubation. The rats were given either ghrelin (1×10-7-1×10-4 g/kg) or saline and MABP and left ventricular indexes were observed for 30 min. Contractile function of the myocytes were detected. RESULTS: No obvious changes of MABP were observed in control group after injection of saline. Intravenous (i.v.) injection of ghrelin decreased MABP in a dose-dependent manner by 11.4%, 15.8% and 27.1%, respectively, in 10-6 g/kg, 10-5 g/kg and 10-4 g/kg groups. No significant difference was observed in LVDP, +dp/dtmax, -dp/dtmax and HR 30 min after i.v. injection of ghrelin. The PTA ±dL/dtmax were significancly decreased in the GRL groups compared with the control group. CONCLUSION: Ghrelin decreases MABP of rats and contractile function of ventricular myocytes in a dose-dependent manner.