Yonsei Med J.  2004 Aug;45(4):649-660. 10.3349/ymj.2004.45.4.649.

Characteristics of Potassium and Calcium Currents of Hepatic Stellate Cells (Ito) in Rat

• Lee KI
• Kong ID
• Baik SK
• Kim HS
• Lee DK
• Kwon SO
• Chun BG

• KMID: 721416
• DOI: http://doi.org/10.3349/ymj.2004.45.4.649

Abstract

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 15microM 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.

Keyword

Hepatic stellate cells; outward K+ currents; inward K+ currents; L-type Ca2+ current

MeSH Terms

Animals
Calcium/*metabolism
Calcium Channel Blockers/pharmacology
Calcium Channels, L-Type/*physiology
Cells, Cultured
Hepatocytes/cytology/*physiology
Immunohistochemistry
Male
Membrane Potentials/drug effects/physiology
Patch-Clamp Techniques
Potassium/*metabolism
Potassium Channel Blockers/pharmacology
Potassium Channels, Voltage-Gated/*physiology
Rats
Rats, Sprague-Dawley