远志水提取物对家兔心肌收缩力及心房尿钠肽分泌的影响

Aqueous Extract of Polygala tenuifolia Willd on Atrial Dynamics and ANP Secretion in Beating Rabbit Atria

摘要:

目的: 观察远志水提取物对家兔心肌收缩力及心房尿钠肽分泌的影响。 方法: 采用家兔离体搏动心房灌流模型,观察远志水提取物对家兔心肌收缩力及心房尿钠肽分泌的影响。环磷酸腺苷(cAMP)和心房尿钠肽(ANP)含量的测定均采用放射免疫法。 结果: 远志水提取物可使家兔的心房每回搏出量、搏动压和灌流液中cAMP流出量比给药前呈现剂量依赖性递增趋势(P<0.05)。同时,它还可以明显地抑制ANP的分泌(P<0.01)。在阻断β-肾上腺素受体(β-adrenorecptor,β-AR)及选择性阻断β₁-AR时能显著抑制远志水提取物对心肌收缩力的增强作用(P<0.05);而选择性阻断β₂-AR时却无任何影响。此外,阻断L-型Ca²⁺通道及选择性抑制蛋白激酶A(PKA)的活性能明显抑制远志水提物对心肌收缩力的增强作用(P<0.05)。 结论: 远志水提取物主要通过影响β₁-AR-cAMP-Ca²⁺信号传导途径增强心肌收缩力,并对ANP分泌具有抑制作用。

Abstract:

Objective: To investigate the effect of aqueous extract of Polygala tenuifolia(APT) on myocardial contractility and atrial natriuretic peptide (ANP) secretion in beating rabbit atria. Method: The APT-induced changes in atrial dynamics, cAMP efflux and ANP secretion were determined in perfused beating rabbit atria. The changes of cAMP and ANP were measured by radioimmunoassay. Result: APT increased atrial stroke volume, pulse pressure and cAMP efflux in a concentration-dependent manner with inhibition of ANP secretion in beating rabbit atria. The APT-induced positive inotropic effect was significantly blocked by pretreatment with blockade of β and β₁-adrenoceptors (AR) (P<0.05) but not β₂-AR. Furthermore, the APT-induced changes in myocardial contractility were attenuated by inhibition of L-type Ca²⁺channel and protein kinase A(PKA) activation with no changes in cAMP efflux. Conclusion: APT could increase atrial dynamics via β₁-AR-cAMP-Ca²⁺signaling and decreases ANP secretion in beating rabbit atria.