Pulmonary vein (PV) cardiomyocytes have the potential to generate spontaneous activity, in contrast to working myocytes of atria. Different electrophysiological properties underlie the potential automaticity of PV cardiomyocytes, one being the hyperpolarization-activated inward current (Ih), which facilitates the slow diastolic depolarization. In the present study, we examined pharmacological characteristics of the Ih of PV cardiomyocytes in rat, guinea pig and rabbit. The results showed that guinea pig and rat PV cardiomyocytes possessed sizeable amplitudes of the Ih, and the Ih of guinea pig was suppressed by Cs+, a blocker of the hyperpolarization-activated cation current. However, the Ih of rat was not suppressed by Cs+, but by Cd2+, a blocker of the Cl- current. The current density of the Ih of rabbit PV cardiomyocytes was significantly smaller than those of other species. This suggests that the ion channels that carry the Ih of PV cardiomyocytes differ among the animal species.

中文翻译：

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从大鼠，豚鼠和兔子分离的肺静脉心肌细胞中超极化激活电流的比较研究。

与心房的正常心肌细胞相比，肺静脉（PV）心肌细胞具有产生自发活性的潜力。PV心肌细胞的潜在自动性是不同的电生理特性的基础，其中之一是超极化激活的内向电流（Ih），它有助于缓慢的舒张期去极化。在本研究中，我们检查了大鼠，豚鼠和兔子中PV心肌细胞Ih的药理特性。结果表明，豚鼠和大鼠PV心肌细胞具有较大的Ih幅度，而Cs +是超极化激活阳离子电流的阻滞剂，可抑制豚鼠的Ih。但是，大鼠的Ih不受Cs +抑制，但受C-电流阻断剂Cd2 +抑制。兔PV心肌细胞的Ih电流密度明显小于其他物种。这表明携带PV心肌细胞Ih的离子通道在动物物种之间是不同的。