Changes in Inward Rectifier K+ Channels in Hepatic Stellate Cells During Primary Culture

ABSTRACT

PURPOSE: This study examined the expression and function of inward rectifier K+ channels in cultured rat hepatic stellate cells (HSC). MATERIALS AND METHODS: The expression of inward rectifier K+ channels was measured using real-time RT-PCR, and electrophysiological properties were determined using the gramicidin-perforated patch-clamp technique. RESULTS: The dominant inward rectifier K+ channel subtypes were K(ir)2.1 and K(ir)6.1. These dominant K+ channel subtypes decreased significantly during the primary culture throughout activation process. HSC can be classified into two subgroups one with an inward-rectifying K+ current (type 1) and the other without (type 2). The inward current was blocked by Ba2+ (100micrometer) and enhanced by high K+ (140mM), more prominently in type 1 HSC. There was a correlation between the amplitude of the Ba2+-sensitive current and the membrane potential. In addition, Ba2+ (300micrometer) depolarized the membrane potential. After the culture period, the amplitude of the inward current decreased and the membrane potential became depolarized. CONCLUSION: HSC express inward rectifier K+ channels, which physiologically regulate membrane potential and decrease during the activation process. These results will potentially help determine properties of the inward rectifier K+ channels in HSC as well as their roles in the activation process.