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目的:研究胍丁胺(Agm)对异丙肾上腺素(Iso)诱发豚鼠乳头状肌早发和晚发后除极(EAD和DAD)的影响及其作用机制。方法:细胞内玻璃微电极技术。结果:(1)Agm明显抑制Iso诱发的EAD和DAD;(2)预先应用NOS抑制剂L-NAME0.5mmol·L~(-1),不能影响Agm1.0mmol·L~(-1)对Iso 20nmol·L~(-1)诱发EAD和DAD的抑制作用;(3)预先应用咪唑啉受体(IR)和肾上腺素能α_2受体(α_2-AR)拮抗剂idazoxan 0.1mmol·L~(-1)则可阻断这种作用。结论:Agm对Iso诱发EAD和DAD的抑制作用由α_2-AR和/或IR介导,并与钙内流减少有关。
AIM: To investigate the effect and mechanism of agmatine on isoproterenol (Iso) -induced premature and post-depolarization (EAD and DAD) induced guinea pig papillary muscles. Methods: Intracellular glass microelectrode technique. Results: (1) Agm significantly inhibited Iso-induced EAD and DAD; (2) Pretreatment with 0.5 mmol·L -1 L-NAME NOS inhibitor did not affect the effect of Agm 1.0 mmol·L -1 on Iso (3) Pretreatment with idazoxan 0.1 mmol·L ~ (-1), an antagonist of imidazoline receptor (IR) and adrenergic α 2 -receptor (α 2 -AR) 1) can block this effect. CONCLUSION: The inhibitory effect of Agm on Iso-induced EAD and DAD is mediated by α 2-AR and / or IR and is associated with decreased calcium influx.