Li X T, He R R
Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China.
Zhongguo Yao Li Xue Bao. 1999 Nov;20(11):1039-42.
To study the effects of agmatine (Agm) on early afterdepolarizations (EAD) and delayed afterdepolarizations (DAD) induced by isoproterenol (Iso) in guinea pig papillary muscles.
EAD and DAD were recorded using intracellular glass microelectrode technique.
(1) EAD and DAD induced by Iso 20 nmol.L-1 were markedly inhibited by pretreatment with Agm 1.0-2.0 mmol.L-1 in a concentration-dependent manner. (2) NG-nitro-L-arginine methyl ester (L-NAME, 0.5 mmol.L-1), a NOS inhibitor, did not affect the inhibitory effects of Agm (1.0 mmol.L-1) on EAD and DAD induced by Iso. (3) The inhibitory effects of Agm (1.0 mmol.L-1) on EAD and DAD induced by Iso (20 nmol.L-1) were eliminated by pretreatment with idazoxan (Ida, 0.1 mmol.L-1), an alpha-2 adrenergic receptor (alpha 2-AR) and imidazoline receptor (IR) antagonist.
The inhibitory effects of Agm on EAD and DAD induced by Iso in papillary muscles is related to the reduction in calcium influx and mediated by alpha 2-AR and/or IR.
研究胍丁胺（Agm）对异丙肾上腺素（Iso）诱导的豚鼠乳头肌早期后除极（EAD）和延迟后除极（DAD）的影响。
采用细胞内玻璃微电极技术记录EAD和DAD。
（1）1.0 - 2.0 mmol.L-1的Agm预处理能以浓度依赖的方式显著抑制20 nmol.L-1 Iso诱导的EAD和DAD。（2）一氧化氮合酶抑制剂NG-硝基-L-精氨酸甲酯（L-NAME，0.5 mmol.L-1）不影响Agm（1.0 mmol.L-1）对Iso诱导的EAD和DAD的抑制作用。（3）α-2肾上腺素能受体（α2-AR）和咪唑啉受体（IR）拮抗剂咪唑克生（Ida，0.1 mmol.L-1）预处理可消除Agm（1.0 mmol.L-1）对20 nmol.L-1 Iso诱导的EAD和DAD的抑制作用。
Agm对乳头肌中Iso诱导的EAD和DAD的抑制作用与钙内流减少有关，且由α2-AR和/或IR介导。
