黄芪对心房收缩力及心房钠尿肽分泌的影响

Effects of Astragalus membranaceus on atrial dynamics and ANP secretion

目的:观察黄芪对家兔心房收缩力及心房钠尿肽分泌的影响。方法:采用家兔离体心房灌流模型,处理0.002,0.002 5,0.003 g.L-1的黄芪水提取液观察家兔心房收缩力及心房钠尿肽分泌的变化,并选择最佳剂量探讨其作用机制。心房钠尿肽含量的测定采用放射免疫法。结果:3个剂量的黄芪水提取液使离体家兔心房每搏输出量由给药前的(694.70±0.01)μL.g-1分别增加到(1 003.00±8.80),(1 120.00±17.71),(1 195.00±8.21)μL.g-1(与给药前比较,分别P<0.05;P<0.01及P<0.001);并使心房搏动压由给药前的(0.82±0.01)kPa分别增加至(0.86±0.01),(0.96±0.01),(1.02±0.01)kPa(与给药前比较,分别P<0.01;P<0.001及P<0.001),且呈现浓度依赖性特征,表明黄芪可增加家兔心房收缩力。0.002 5 g.L-1黄芪水提取液显著抑制心房钠尿肽的分泌[给药前心房钠尿肽含量为(18.74±0.02)ng.min-1.g-1,给药后为(12.97±0.14)ng.min-1.g-1;与给药前比较P<0.001]。L-型Ca2+通道阻断剂硝苯地平(1.0μmol.L-1)及逆向Na+-Ca2+交换体抑制剂KB-R 7943(10.0μmol.L-1)阻断了黄芪增强心房收缩力的作用,但均未能改变黄芪对心房钠尿肽分泌的抑制效应。结论:黄芪主要通过影响L-型Ca2+通道及Na+-Ca2+交换体增强心房收缩力,并对心房钠尿肽分泌具有抑制性调节作用。

Objective： To define the effects of Astragalus membranaceus on the atrial dynamics and ANP secretion in the perfused beating rabbit atria. Method： The experiments have been done in isolated perfused beating rabbit atria. ANP was measured by radioimmunoassay in the atrial perfusate in real-time base. Result： A. membranaceus （2. 0, 2. 5, 3.0μL·g^-1 ） could increase atria stroke volume from （694. 70 ± 0. 01 ） μL·g^-1 （ p 〈 0. 05 ） to （ 1 003.00 ± 8. 80）μL·g^-1（ p 〈 0. 001 ） ; （ 1120. 00 ±17.71 ）μL·g^-1 and （1 195.00± 8.21 ） μL·g^-1（ p 〈 0. 001 ）, respectively, and its could difference increase atrial pulse pressure from （0. 82 ± 0.01） kPato （0.86±0.01） kPa （P〈0.01）; （0.96 ±0.01） kPa （P 〈0.001） and （1.02 ±0.01） kPa （P 〈0.001）, respectively; A. membranaceus obviously increased rabbit atrial dynamics with dose-dependent manner. Simultaneously, A. membranaceus inhibited ANP secretion. Nifedipine （ 1.0μmol· L^-1 ）, a L-type Ca^2＋ channel inhibitor, and KB-R 7943 （ 10. 0μmol· L^-1 ）, an inhibitor of reversed Na^＋ -Ca^2＋ exchanger, blocked the effects of A. membranaceus-induced augmentation of atrial dynamics but failed to modulation the inhibition of A. membranaceus on ANP secretion. Conclusion： A. membranaceus increases the atrial dynamics via Na^＋ -Ca^2＋ exchanger and L-type Ca^2＋ channel and negatively modulates ANP secretion in beating rabbit atria.