¡¾Abstract¡¿ AIM: To examine the effects of angiotensin ¢ò (Ang¢ò) on intracellular free calcium concentration ([Ca2+]i) in human atrial myocytes and the antagonism effect of telmisartan. METHODS: Single human atrial myocyte was isolated. Four groups were included in the experiment: control group, Ang¢ò group, telmisartan group, and Ang¢ò + telmisartan group. Confocal microscope was used with Fluoª²3/AM as calcium indicator to detect the changes of [Ca2+]i immediately and 15 minutes respectively after the drug intervention. RESULTS: The intracellular fluoresence intensity of singular cardiomyocytes in control and telmisartan groups was low and the intracellular fluoresence intensity of singular cardiomyocytes in Ang¢ò group was significantly higher than that in the control group 15 minutes after intervention (P<0.01). When telmisartan was added simultaneously with Ang¢ò intervention, the values were much lower compared with those in Ang¢ò group (P<0.01). CONCLUSION: Ang¢ò induces intracellular calcium overload in human atrial myocytes and telmisartan can decrease [Ca2+]i overload in human atrial myocytes induced by Ang¢ò. ......