Effects of angiotensinII on potassium ion currents of human atrial myocytes and the antagonism effect of telmisartan

    ZHANG Dianª²Xin,HUANG Lan, WANG Haiª²Chang, ZHANG Rongª²Qing,CHENG HEª²Xiang, LIU Bing, ZHANG Qing£¬GUO Wenª²Yi

    1Department of Cardiovasology, Xinqiao Hospital, Third Military Medical University, Chongqing 400038,China,2Department of Cardiovasology, Xijing Hospital, Fourth Military Medical University, Xi¬ðan 710033 ,China

    ¡¾Abstract¡¿AIM£º To observe the effects of angiotensin ¢ò (Ang¢ò) on potassium currents of human atrial myocytes so as to reveal the mechanisms of atrial arrhythmia induced by Ang¢ò, and to provide a laboratory basis for the application of angiotensin ¢ò receptor antagonist in the treatment of atrial arrhythmias. METHODS: Single human atrial myocyte was isolated and the conventional wholeª²cell configuration of patchª²clamp technique was used to detect membrane Ik1 and Ito. The experiment was conducted in four groups: control group, Ang¢ò group, telmisartan group, and Ang¢ò + telmisartan group. RESULTS: Compared with the control group, Ang¢ò of 0.1 ¦Ìmol/L significantly decreased the peak density of Ito in human atrial myocytes (pA/pF,6.55¡À0.52 vs 12.65¡À1.06 , P<0.01). Under the voltage of -100 mV, Ang¢ò significantly increased the peak density of IK1 (pA/pF, -9.31¡À1.02 vs -5.23¡À0.98 , P<0.01). Telmisartan of 0.01 ¦Ìmol/L had no significant effect on Ik1 and Ito in human atrial myocytes, but it antagonized the effects of Ang¢ò. In Ang¢ò + telmisartan group, the peak density of Ito (pA/pF, 11.74¡À1.28) and the peak density of IK1 ( pA/pF, -6.13¡À1.15) were both significantly different with those in Ang¢ò group(P< 0.01). CONCLUSION: Ang¢ò has significant electrophysiological effects on human atrial myocytes. Ang¢ò of 0.1 ¦Ìmol/L significantly increases the peak density of IK1, but decreases the peak density of Ito in human atrial myocytes. Telmisartan antagonizes the effects of Ang¢ò on human atrial myocytes. ......