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KMID : 0370220160600050256
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Yakhak Hoeji
2016 Volume.60 No. 5 p.256 ~ p.260
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Activation of P2X Purinoceptor by Shear Stress in Rat Atrial Myocytes
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Son Min-Jeong
Kim Joon-Chul
Wang Jun
Kim Kyeong-Hee
Woo Sun-Hee
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Abstract
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Atrial myocytes are subjected to shear stress under physiological and pathological conditions during cardiac cycle. It has been recently suggested that ATP release of atrial cells induces longitudinal Ca2+ wave via activation of P2Y1 purinergic signaling in rat atrial myocytes under shear stress. In the present study, we examined whether P2X purinoceptor, a non-selective cation channel, is activated in these cells using a whole-cell patch clamp combined with a pressurized micro- flow system. Shear stress of ~16 dyne/cm2(1-s long) produced a slow inward current(ISS) at ?70 mV in symmetrical CsCl- rich solutions. Removal of external Ca2+ significantly enhanced the ISS by approximately 140%. Pre-treatment of suramin(10 킡), the general P2-purinoceptor antagonist, suppressed the ISS by ~70%. In addition, the ISS was inhibited by ~50% by pre-exposure to P2X purinoceptor inhibitor, iso-PPADS(100 킡). Inhibition of transient receptor potential melas- tatin 4, the Ca2+-activated non-selective cation channel, using 9-phenanthrol(30 킡) decreased ISS by ~30%. When the delayed rectifying K+ channels, that have slight permeability to Cs+, were blocked using 4-aminopyridine(200 킡), ISS was not altered. Our data suggest that shear stress activates P2X purinoceptors in atrial myocytes, thereby partly contributing to shear-activated slow cation influx at resting membrane potential.
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KEYWORD
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atrial myocytes, shear stress, P2X purinoceptor, non-selective cation current
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