Al-Bazzaz F, Jayaram T
Exp Lung Res. 1981 May;2(2):121-30. doi: 10.3109/01902148109052308.
Calcium is considered to be modulator of paracellular shunt pathway as well as several cell functions such as ion transport. We used calcium ionophore A23187 to study effect of mobilization of calcium on chloride and sodium transport in canine tracheal epithelium. This epithelium secretes Cl and absorbs Na under short-circuit conditions. Sheets of canine tracheal mucosa were mounted in chambers, perfused with Krebs-Henseleit solution at 37 degrees C and oxygenated. Unidirectional fluxes of 22Na and 36Cl were measured in matched paired mucosae under short-circuit conditions. Net flux of each ion was calculated from these unidirectional fluxes, before and after addition of A23187 (10(-6) M) to submucosal bath. Short-circuit current and potential difference were measured. From these values conductance was calculated. Initially, short-circuit current, potential difference, and conductance were 31 +/- 8 microA/cm(2), 26 +/- 4 mV, and 1.2 +/- 0.2 mS/cm(2), respectively, and increased significantly after A23187 to 76 +/- 20 microA/cm(2), 41 +/- 5 mV, and 1.8 +/- 0.4 mS/cm(2), respectively (mean +/- SE for 10 tissues). Net Cl secretion increased from 0.83 +/- 0.23 muEq/cm(2) hr to 2.84 +/- 0.38 muEq/cm(2) hr (P less than .002) and net Na absorption of 0.50 +/- 0.14 muEq/cm(2) hr was abolished (P less than .02). These data show that increase in cellular levels of calcium increases chloride secretion and abolishes sodium transport. Intracellular calcium appears to regulate cell membrane permeability to chloride and sodium.U
钙被认为是细胞旁分流途径的调节剂，也是多种细胞功能（如离子转运）的调节剂。我们使用钙离子载体A23187来研究钙动员对犬气管上皮细胞中氯和钠转运的影响。在短路条件下，这种上皮细胞分泌氯离子并吸收钠离子。将犬气管黏膜片安装在小室中，在37℃下用克雷布斯-亨塞尔特溶液灌注并进行氧合。在短路条件下，在配对的黏膜中测量22Na和36Cl的单向通量。在向黏膜下浴中添加A23187（10^(-6) M）之前和之后，根据这些单向通量计算每种离子的净通量。测量短路电流和电位差。根据这些值计算电导率。最初，短路电流、电位差和电导率分别为31±8 μA/cm²、26±4 mV和1.2±0.2 mS/cm²，在添加A23187后显著增加，分别为76±20 μA/cm²、41±5 mV和1.8±0.4 mS/cm²（10个组织的平均值±标准误）。净氯分泌从0.83±0.23 μEq/cm²·小时增加到2.84±0.38 μEq/cm²·小时（P<0.002），净钠吸收0.50±0.14 μEq/cm²·小时被消除（P<0.02）。这些数据表明，细胞内钙水平的增加会增加氯分泌并消除钠转运。细胞内钙似乎调节细胞膜对氯和钠的通透性。
