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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．
Objective: To observe the effect of sodium alginate (PSS) on the action potentials and contractile force (FC) of guinea pig papillary muscles. Methods: The fast response action potential (FAP) and slow response action potential (SAP) of guinea pig papillary muscles were recorded by intracellular microelectrode technique. Results: PSS (≥50 mg · L-1) decreased the FC and APP of FAP in a concentration-dependent manner, but decreased the resting potential and action potential amplitude (APA) and the maximum depolarization rate in stage 0 Vmax) had no significant effect. PSS (≥15 mg · L-1) decreased the Vmax and APA of SAP induced by BaCl2 in a concentration-dependent manner, and APD shortened. After isoproterenol was added into Tyrode’s solution, 1 μmol·L-1 was normalized. PSS (≥15mg · L-1) decreased the APA of SAP induced by isoproterenol in a concentration-dependent manner, shortened the APD, and returned to normal after increasing the concentration of extracellular Ca2 +. Conclusion: PSS selectively inhibits the slow inward current.