BACKGROUNDS/AIMS: This study aimed to investigate the effects of angiotensin II (ANG II) and its receptor antagonist (losartan) on the contraction and growth of HSCs. METHODS: HSCs were isolated from Sprague Dawley rat and cultured at various conditions as follows: control, pretreatment of 10(-5) M ANG II, pretreatment of 10(-5) M endothelin, and pretreatment of 10(-5) M ANG II and 10(-6) M losartan. We conducted morphologic analysis with cellular area and length by image analysis system to estimate cell growth in each group. In addition, we measured the change of intracellular calcium currents via electrophysiological methods to evaluate the contractile effect of ANG II and losartan on HSCs. RESULTS: At the fifth day of incubation, the mean cellular area of ANG II-pretreated group and ANG II with losartan-pretreated group were 704.68+/-22.6 micrometer2 and 332.90+/-32.6 micrometer2, respectively. This difference was statistically significant (p<0.05). ANG II induced an increase in the intracellular calcium current by 22.0+/-3.0% compared with basal current level (p<0.05). However, when losartan was pretreated, ANG II did not cause a significant increase in calcium current (3.1+/-0.8%, p>0.05). CONCLUSION: ANG II accelerates the contraction and growth of HSCs, while its receptor blocker, losartan, inhibits the contraction and growth of HSCs.