O'Doherty J, Stark R J
Pflugers Arch. 1982 Jul;394(1):26-31. doi: 10.1007/BF01108304.
Acetylcholine (ACh) released from vagal terminals increases the permeability of the pancreatic acinar membrane to Na+ and Ca2+ ions. In this report, we compare the induced changes in intracellular Na+ and Ca2+ electrode potentials (ENa and ECa) due to ACh-stimulation of acini with those observed during stimulation with the calcium ionophore, A23187, which mimicks the action of ACh on pancreatic secretion. Stimulation with ACh concentrations varying from 10(-8) to 10(-5) M and with A23187 concentrations of 10(-6) and 10(-5) M caused parallel increases in cytosolic Ca2+ and Na+ ([Ca]i, [Na]i). The magnitude of the increases in [Ca]i and [Na]i due to A23187-stimulation further indicate that when presented with a calcium challenge the acinar cells continue to regulate [Ca]i close to physiological levels and suggest that the observed increases in ionized calcium could reflect much larger increases in complexed Ca2+. ACh-stimulation following removal of either extracellular Na+ or Ca2+ ions, eliminated the intracellular increases found when the removed ions is present, but did not affect the increases usually found with the other ion. The independence of the permeability changes to either the presence of Ca2+ or Na+ indicates the ACh-induced currents carried by Na+ and Ca2+ are also independent. The selective translocation of Na+ and Ca2+ during acetylcholine-stimulation in a manner analogous to the changes observed when ionophore A23187 was used as stimulus, indicates the ability of the activated acinar membrane to function as an ionophore.
迷走神经末梢释放的乙酰胆碱（ACh）可增加胰腺腺泡膜对Na⁺和Ca²⁺离子的通透性。在本报告中，我们比较了ACh刺激腺泡后细胞内Na⁺和Ca²⁺电极电位（ENa和ECa）的诱导变化，以及在用钙离子载体A23187刺激时观察到的变化，A23187模拟了ACh对胰腺分泌的作用。用浓度从10⁻⁸到10⁻⁵M的ACh以及浓度为10⁻⁶和10⁻⁵M的A23187刺激，导致胞质Ca²⁺和Na⁺（[Ca]i，[Na]i）平行增加。由于A23187刺激导致的[Ca]i和[Na]i增加的幅度进一步表明，当面临钙挑战时，腺泡细胞继续将[Ca]i调节至接近生理水平，并表明观察到的游离钙增加可能反映了络合Ca²⁺的更大增加。去除细胞外Na⁺或Ca²⁺离子后进行ACh刺激，消除了去除离子存在时发现的细胞内增加，但不影响通常在另一种离子存在时发现的增加。通透性变化对Ca²⁺或Na⁺存在的独立性表明，由Na⁺和Ca²⁺携带的ACh诱导电流也是独立的。在乙酰胆碱刺激期间，Na⁺和Ca²⁺的选择性转运方式类似于使用离子载体A23187作为刺激时观察到的变化，这表明活化的腺泡膜具有作为离子载体的功能。
