【摘要】 目的：观察藻酸双酯钠（ＰＳＳ）对豚鼠乳头状肌动作电位和收缩力（ＦＣ）的影响．方法：利用细胞内微电极技术记录豚鼠乳头状肌的快反应动作电位（ＦＡＰ）和慢反应动作电位（ＳＡＰ）．结果：ＰＳＳ（≥５０ｍｇ·Ｌ－１）浓度依赖性地使ＦＣ减弱和ＦＡＰ的动作电位时程（ＡＰＤ）缩短，但对静息电位和动作电位幅度（ＡＰＡ）及０期最大除极速率（Ｖｍａｘ）均无显著影响．ＰＳＳ（≥１５ｍｇ·Ｌ－１）浓度依赖性地使ＢａＣｌ２诱发的ＳＡＰ的Ｖｍａｘ和ＡＰＡ降低，ＡＰＤ缩短，在台氏液中加入异丙肾上腺素１μｍｏｌ·Ｌ－１后，各项参数恢复正常．ＰＳＳ（≥１５ｍｇ·Ｌ－１）浓度依赖性地使异丙肾上腺素诱发的ＳＡＰ的ＡＰＡ降低，ＡＰＤ缩短，提高细胞外Ｃａ２＋浓度后各项参数均恢复正常．结论：ＰＳＳ选择性抑制慢内向电流．更多还原

【Abstract】 AIM: To examine the effects of polysaccharide sulfate (PSS) on the action potentials and contractile force in guinea pig papillary muscles. METHODS: Using intracellular microelectrode to record fast (FAP) and slow (SAP) action potentials. RESULTS: PSS (≥50 mg·L -1 ) caused concentration dependent decreases in the contractile force and the action potential duration (APD) of FAP without affecting the resting potential (RP), action potential amplitude (APA), and maximal upstroke velocity ( V max ). The V max , APA, and APD of BaCl 2 induced SAP were concentration dependently decreased by PSS (≥15 mg·L -1 ) and the effects were antagonized by isoprenaline (1 μmol·L -1 ). The APA and APD of isoprenaline induced SAP were decreased by PSS (≥15 mg·L -1 ) in a concentration dependent manner and the effects were attenuated by elevation of extracellular Ca 2+ concentration. CONCLUSION: PSS selectively inhibited the slow inward current.更多还原