Polonchuk L O, Frolov V A, Yuskovich A K
Belozersky Institute of Physico-Chemical Biology, Moscow State University.
Membr Cell Biol. 1997;11(2):225-42.
Arachidonic acid (AA) is known to inhibit intercellular conductance in normal and tumour cells. We showed that junctional conductance (Gj) in isolated murine hepatocytes was relatively tolerant to the uncoupling effect of AA. Extracellular application of 100 microM AA decreased Gj in less than 50% of hepatocytes, and the effect was much slower in other cells (10-15 min vs. 2-5 min, respectively). The uncoupling effect of AA did not depend on the intracellular [Ca2+] within the pCa(i) range 7.7-9.0. Similar results were obtained using the pipette-filling solutions with low (1 mM) and high (10 mM) concentrations of a Ca-chelating agent (EGTA). To verify whether the resistance of the hepatocyte Gj to AA may result from the "wash-out" of the intracellular intermediates during the intracellular dialysis, Gj was measured 10-45 min after the preincubation of hepatocytes with AA. After such a treatment, in 62% of cell pairs the Gj values recorded did not differ from the control. Extracellular or intracellular acidification (pHo 6.0 or pHi 5.0-6.0) did not markedly affect the AA action. However, in some cases AA induced the recovery of Gj blocked after intracellular acidification, the phenomenon suggesting the activation of the H+ transport in the presence of AA. Possible mechanisms of the observed resistance of junctional conductance of mouse hepatocytes in primary culture are discussed.
已知花生四烯酸（AA）可抑制正常细胞和肿瘤细胞的细胞间电导。我们发现，分离的小鼠肝细胞中的连接电导（Gj）对AA的解偶联作用相对耐受。细胞外施加100微摩尔AA可使不到50%的肝细胞中的Gj降低，而在其他细胞中这种作用要慢得多（分别为10 - 15分钟和2 - 5分钟）。AA的解偶联作用不依赖于细胞内pCa（i）范围在7.7 - 9.0内的[Ca2+]。使用含有低浓度（1毫摩尔）和高浓度（10毫摩尔）Ca螯合剂（乙二醇双四乙酸，EGTA）的移液管填充溶液也得到了类似结果。为了验证肝细胞Gj对AA的抗性是否可能是由于细胞内透析过程中细胞内中间产物的“洗脱”所致，在肝细胞与AA预孵育10 - 45分钟后测量Gj。经过这样的处理后，在62%的细胞对中记录的Gj值与对照无差异。细胞外或细胞内酸化（pHo 6.0或pHi 5.0 - 6.0）对AA的作用没有明显影响。然而，在某些情况下，AA可诱导细胞内酸化后被阻断的Gj恢复，这一现象表明在AA存在下H+转运被激活。本文讨论了原代培养的小鼠肝细胞连接电导观察到的抗性的可能机制。
