Effects of pH on the potassium current in rabbit corneal epithelial cells.
Effects of pH on the potassium current in rabbit corneal epithelial cells.
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pH值对兔角膜上皮细胞钾电流的影响。
DOI：
10.1152/ajpcell.1997.272.2.c744
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
Rae,JL
中科院分区：
文献类型：
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作者：
Rich,A;Bartling,C;Farrugia,G;Rae,JL
用两性霉素穿孔膜片全细胞电压钳技术测定pH对新鲜分散的兔角膜上皮细胞K+电导的影响。标准林格液(pH 7.35)后用pH 6.00林格液灌流，使外向钾离子选择电流(I(K))从12 0+/-2 9增加到312+/-pA，并使静息膜电位(Em)从-5 2+/-5增加到-62+/-3 mV(n=15，P<0.0 5或0.0 5)。PH升高至8.5，I(K)由183+/-40降至114+/-35 pA(n=6，P<0.05)，去极化Em由-63+/-6降至-53+/-5 mV(n=6，P<0.05)。弱电解质(NH_4)_2SO_4细胞内酸化使I(K)从83+/-15增加到183+/-20pA(n=4，P=0.01)，超极化Em从-51+/-8增加到-68+/-6 mV(P=0.002)。细胞内碱化使I(K)降至66+/-10pA，去极化Em降至-36+/-8 mV(P=0.009)。单通道研究表明，在Em为15 mV时，当镀液pH从7.35降至6.00时，单通道开放概率(NPO)从0.43增至0.64。在细胞贴壁贴片中，NPO也增加。在-100到+100 mV范围内测量的单位电导没有改变。这些结果表明，pH通过改变NPO来调节兔角膜上皮细胞的I(K)。
The effects of pH on K+ conductance were measured using the amphotericin perforated-patch whole cell voltage-clamp technique in freshly dispersed rabbit corneal epithelial cells. Bath perfusion with pH 6.00 Ringer solution after standard Ringer solution (pH 7.35) increased outward K+-selective current (I(K)) from 120 +/- 29 to 312 +/- 64 pA during a step depolarization to +50 mV and hyperpolarized the resting membrane potential (Em) from -52 +/- 5 to -62 +/- 3 mV (n = 15, P < or = 0.05). Increasing bath pH to 8.5 decreased I(K) from 183 +/- 40 to 114 +/- 35 pA (n = 6, P < or = 0.05) and depolarized Em from -63 +/- 6 to -53 +/- 5 mV (n = 6, P < or = 0.05). Intracellular acidification using the weak electrolyte (NH4)2SO4 also increased I(K) from 83 +/- 15 to 183 +/- 20 pA (n = 4, P = 0.01) and hyperpolarized Em from -51 +/- 8 to -68 +/- 6 mV (P = 0.002). Intracellular alkalinization reduced I(K) to 66 +/- 10 pA and depolarized Em to -36 +/- 8 mV (P = 0.009). Single channel studies in perforated outside-out vesicles showed that a decrease in bath pH from 7.35 to 6.00 was accompanied by an increase in the single channel open probability (NPo) from 0.43 to 0.64 at an Em of 15 mV. NPo was also increased in cell-attached patches. The unitary conductance, measured from -100 to +100 mV, was not changed. These results indicate that pH modulates I(K) in rabbit corneal epithelial cells by changes in NPo.