전단 스트레스에 의한 심방근세포 커넥신 해미채널의 활성화

Activation of Connexin Hemichannel by Shear Stress in Atrial Myocytes

Abstract Shear stress induces global Ca waves in atrial myocytes and this Ca wave has been shown to be sensitive to connexin (Cx) channel interventions. In this study, we investigated whether shear stress activates Cx by measuring dye flux through the Cx channels in rat atrial myocytes. Because the pores of the hemichannels are large enough to permit flux of large molecules up to 1000 MW, we used a Cx channel-permeable dye, Calcein, and a Cx-impermeable dye, Oregon to evaluate Cx-specific activity under shear stress. Application of shear stress (~16 dyn/cm 2 ) using micro-jet apparatus to single atrial cells induced a significant increase in cellular Calcein efflux. The Calcein efflux was largely potentiated by the use of Ca -free external solutions which enhance Cx hemichannel activity. However, it was suppressed by 95% following the pre-treatment of La (2 mM), a gap junction blocker. Pre-exposure to the pannexin inhibitor probenecid (800 mM) did not alter the calcein efflux under shear stress. In contrast, the Oregon signal was not significantly affected by shear stress exposure, suggesting that calcein efflux by shear exposure was not due to nonspecific increase in membrane permeability. In a monolayer of HL-1 atrial cell culture treated by the external solutions containing Cx-permeable Lucifer Yellow dye, cellular dye influx was increased by shear stress. These results suggest that shear stress activates Cx hemichannels in atrial myocytes.