洛土辛对心肌及阴茎海绵体环核苷酸含量和收缩功能的影响

Effects of lotusine on cyclic nucleotide levels and contractile function in rat myocardium and rabbit corpus cavernosum

目的 研究洛土辛 (Lot)对磷酸二酯酶 (PDE)Ⅲ或Ⅴ亚型的抑制作用及选择性。方法 采用放射免疫测定法及收缩张力记录。结果 Lot和氨力农(Amr)剂量依赖性地增加大鼠心肌cAMP含量 ,且Lot的作用强于Amr。在家兔阴茎海绵体 ,Lot和扎普司特 (Zap)可剂量依赖性地增加海绵体cGMP含量 ,Lot的作用远弱于Zap。Lot,罂粟碱 (Pap)、Zap及Amr可显著抑制预先用苯肾上腺素诱发的阴茎海绵体血管收缩 ,其EC50 分别依次为Zap >Pap >Amr >Lot。结论 提示洛土辛的作用机理可能与选择性的抑制PDEⅢ有关。

AIM To study the inhibitory effect and selectivity of lotusine (Lot), an alkaloid extracted from Nelumbo nucifera Gaertn., on phosphodiesterase Ⅲ or Ⅴ. METHODS To use radioimmunoassay and recording of contractile force. RESULTS Lot (0.1-3 μmol·L -1 ) and amrinone (Amr, 0.1-10 μmol·L -1 ) concentration dependently increased the cyclic AMP level of the rat myocardium. The effect of Lot was stronger than that of Amr. Lot and zaprinast(Zap)enhanced the cyclic GMP level in rabbit corpus cavernosum in concentration dependent manner. This effect of Lot was much weaker than that of Zap. Lot, papaverine (Pap),Zap and Amr obviously inhibited the rabbit corpus cavernosum contractile response induced by phenylephrine (10 μmol·L -1 ). The -lg EC 50 (mol·L -1 )of them was Zap(5)>Pap(4.9)>Amr(4.6)>Lot (3.7) respectively. CONCLUSION Lot selectively inhibits phosphodiesterase(PDE)Ⅲ activity and maybe a novel PDE Ⅲ inhibitor.