内源性NO介导肾上腺髓质素对家兔离体缺氧性肺动脉的舒张作用

Effects of adrenomedullin on the contraction of the pulmonary artery in vitro in rabbits

目的探讨肾上腺髓质素在缺氧性肺血管收缩中的作用及其与内源性NO的关系。方法将制备的离体兔肺动脉环分为单纯缺氧对照组、ADM孵育组、ADM +L～NNA孵育组。用离体血管环技术观察肺动脉环收缩张力的变化。结果在常氧条件下 ,经ADM孵育30min后肺动脉环对NA的预收缩反应张力较正常对照组降低21.9 % ;ADM +L～NNA共同孵育后的肺动脉环对NA的预收缩张力 (3.07±0.65克·张力/毫克·湿重 )明显高于ADM孵育组 (P<0 01) ,但与正常对照组比较 ,差异无显著性意义 (P>0 05)。NA预收缩的肺动脉环在急性缺氧介质中立即出现明显的缺氧性收缩峰 ,其收缩张力变化为0.44±0.11克·张力 /毫克·湿重 ;经ADM孵育30min的肺动脉环NA预收缩后缺氧性收缩峰的幅度较单纯NA预收缩的肺动脉环降低了36.4 % (P<0 05) ;而ADM +L～NNA共同孵育30min的肺动脉环NA预收缩后的缺氧性收缩张力与单纯缺氧组比较差异无显著性意义(P>0.05)。结论在离体条件下 ,ADM可致NA预收缩的肺动脉环缺氧性收缩反应降低 ,L～NNA可逆转ADM降低肺动脉缺氧性收缩反应的作用 ,这种作用可部分是由NO介导的。

Objective To explore the effects of adrenomedullin on the contraction of the pulmonary artery preconstricted by noradrenaline and it's correlation with Nitric Oxide in rabbits.Methods The prepared pulmonary arteryrings were randomly divided into control group,ADM incubation group and ADM+L～NNA incubation group.The tension changes of pulmonary artery were monitored in vitro.Results Under normoxic condition,ADM incubation for30min reduced21.9%contractile response toα～adrenoceptor against NA on the pulmonary arterial rings compared with the controls(P<0.01)and the action of ADM was abolished in ADM+L～NNA incubation group.The contractile tensions to NA in ADM+L～NNA incubation group were3.07±0.65g.tension/mg.wet weight and significantly inˉcreased compared with that of ADM incubation group(P<0.01),but there was no significant difference between the controls and ADM+L～NNA incubation group(P>0.05).Under hypoxic condition,pulmonary arterial rings preconstricted by NA produced acute hypoxic vasocontraction responses.ADM incubation for30min reduced36.4%acute hypoxic vasocontraction response on the pulmonary arterial rings preconstricted by NA compared with hypoxic controls(P<0.05)and the actions that ADM deˉcreased acute hypoxic vasocontraction response on the pulmonary arterial rings preconstricted by NA were similarly reversed by incubating combined with L～NNA.Conclusion These results indicate that ADM is a potent vasodilator of the pulmonary artery in vitro under normoxic and hypoxic conditions,and that the ADM-induced relaxation of the pulmonary artery rings preconstricted by NA under hypoxic conditions is impaired by L～NNA.The vasorlaxant actions of ADM are partially mediated by NO.