Characteristics of potassium and calcium currents of hepatic stellate cells (ito) in rat.

Hepatic stellate cells (HSCs) are known to play a role in the pathogenesis of the increased intrahepatic vascular resistance found in chronic liver diseases. The aim of this study was to evaluate the K+ and Ca2+ currents in cultured HSCs from rat liver, through the patch-clamp technique. Most cells were positive for desmin immunostain after isolation and in alpha-smooth muscle actin immunostain after 10 - 14 days of culturing. Outward and inward rectifying K+ currents were confirmed. Two different types of K+ currents were distinguished: one with the inward rectifying current and the other without. The outward K+ currents consisted of at least four components: tetraethylammonium (TEA)-sensitive current, 4-aminopyridine (4-AP)-sensitive current, pimozide-sensitive current and three blocker-resistant current. The peaks of the outward K+ currents evoked by a depolarizing pulse were decreased to 32.0 +/- 3.0, 62.8 +/- 3.7 and 32.8 +/- 3.5% by 5 mM TEA, 2 mM 4-AP and 15 micro M pimozide, respectively. Moreover, the combined application of three blockers caused 86.6 +/- 4.8% suppression. The inward currents evoked hyperpolarizing pulses were inwardly rectifying and almost blocked by Ba2+. Elevation of external K+ increased the inward current amplitude and positively shifted its reversal potential. Voltage- dependent Ca2+ currents which were completely abolished by Cd2+ and nimodipine were detected in 14 day cultured HSCs. In this study, the cultured HSCs were found to express outward K+ currents composed of multiple pharmacological components, Ba2+-sensitive inward rectifying K+ current and L-type Ca2+ current.

[Inhibitory effect of angiotensin II receptor antagonist on the contraction and growth of hepatic stellate cells].

BACKGROUND/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 micro m2 and 332.90+/-32.6 micro m2, 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.