ACETYLCHOLINE-INDUCED NA+ INFLUX IN THE MOUSE LACRIMAL GLAND ACINAR-CELLS - DEMONSTRATION OF MULTIPLE NA+ TRANSPORT MECHANISMS BY INTRACELLULAR NA+ ACTIVITY MEASUREMENTS
ACETYLCHOLINE-INDUCED NA+ INFLUX IN THE MOUSE LACRIMAL GLAND ACINAR-CELLS - DEMONSTRATION OF MULTIPLE NA+ TRANSPORT MECHANISMS BY INTRACELLULAR NA+ ACTIVITY MEASUREMENTS
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DOI：
10.1007/bf01872126
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发表时间：
1987-01-01
影响因子：
2.4
通讯作者：
NISHIYAMA, A
中科院分区：
文献类型：
--
作者：
SAITO, Y;OZAWA, T;NISHIYAMA, A
用双管Na+选择性微电极直接测定小鼠离体泪液腺泡细胞内Na+活性。在非刺激条件下，ANAI为6.5。+-。0.5 mm，膜电位(Vm)为-38.9±-。0.4 mV。加入1 mM哇巴因或用无K+溶液灌流使膜轻微去极化，导致Anai逐渐增加。用乙酰胆碱(ACh，1µm)刺激，在5分钟内使膜超极化约20 mV，使Anai增加约9 mm。阿米洛利(0.1 mM)可使ACh诱发的ANAI增加约50%，但在非刺激和ACh刺激条件下均不影响Vm和输入阻力。加/减20 mM NH4Cl或用HCO3-/CO2-缓冲溶液代替Tris+-缓冲盐水使腺泡细胞的ANAI增加几mm。用无氯硝酸溶液、1 mM速尿或0.5 mM布美他尼溶液灌流，对静息ANAI水平无明显影响，但可使ACh引起的ANAI升高约30%。消除代谢产物阴离子(谷氨酸、富马酸和丙酮酸)可降低静息ANAI和ACh诱导的ANAI升高。这些结果表明，ACh激活了多种Na+进入机制，即Na+/H+交换机制、Na-K-Cl共转运机制和有机底物耦合的Na+转运机制。
In the isolated, superfused mouse lacrimal gland, intracellular Na+ activities (aNai) of the acinar cells were directly measured with double-barreled Na+-selective microelectrodes. In the nonstimulated condition aNai was 6.5 .+-. 0.5 mM and membrane potential (Vm) was -38.9 .+-. 0.4 mV. Addition of 1 mM ouabain or superfusion with a K+-free solution slightly depolarized the membrane and caused a gradual increase in aNai. Stimulation with acetylcholine (ACh, 1 .mu.M) caused a membrane hyperpolarization by about 20 mV and an increase in aNai by about 9 mM in 5 min. The presence of amiloride (0.1 mM) reduced the ACh-induced increase in aNai by approximately 50%, without affecting Vm and input resistance in both nonstimulated and ACh-stimulated condition. Acid loading the acinar cells by an addition/withdrawal of 20 mM NH4Cl or by replacement of Tris+-buffer saline solution with HCO3-/CO2-buffered solution increased aNai by a few mM. Superfusion with a Cl--free NO3- solution or 1 mM furosemide or 0.5 mM bumetanide-containing solution had little effect on the resting aNai lelvels, however, it reduced the ACh-induced increase in aNai by about 30%. Elimination of metabolite anions (glutamate, fumarate and pyruvate) from the superfusate reduced both the resting aNai and the ACh-induced increase in aNai. The present results suggest the presence of multiple Na+ entry mechanisms activated by ACh, namely, Na+/H+ exchange, Na-K-Cl cotransport and organic substrate-coupled Na+ transport mechanisms.