Sonnentag T, Siegel W K, Bachmann O, Rossmann H, Mack A, Wagner H J, Gregor M, Seidler U
1. Medizinische Klinik und, Tübingen, Germany.
Am J Physiol Gastrointest Liver Physiol. 2000 Jul;279(1):G40-8. doi: 10.1152/ajpgi.2000.279.1.G40.
Concomitant Na(+)/H(+) and Cl(-)/HCO(3)(-) exchange activation occurs during stimulation of acid secretion in cultured rabbit parietal cells, possibly related to a necessity for volume regulation during the secretory process. We investigated whether cytoplasmic volume changes occur during secretagogue stimulation of cultured rabbit parietal cells. Cells were loaded with the fluorescent dye calcein, and the calcein concentration within a defined cytoplasmic volume was recorded by confocal microscopy. Forskolin at 10(-5) M, carbachol at 10(-4) M, and hyperosmolarity (400 mosmol) resulted in a rapid increase in the cytoplasmic dye concentration by 21 +/- 6, 9 +/- 4, and 23 +/- 5%, respectively, indicative of cell shrinkage, followed by recovery to baseline within several minutes, indicative of regulatory volume increase (RVI). Depolarization by 5 mM barium resulted in a decrease of the cytoplasmic dye concentration by 10 +/- 2%, indicative of cell swelling, with recovery within 15 min, and completely prevented forskolin- or carbachol-induced cytoplasmic shrinkage. Na(+)/H(+) exchange inhibitors slightly reduced the initial cell shrinkage and significantly slowed the RVI, whereas 100 microM bumetanide had no significant effect on either parameter. We conclude that acid secretagoguges induce a rapid loss of parietal cell cytoplasmic volume, followed by RVI, which is predominantly mediated by Na(+)/H(+) and Cl(-)/HCO(3)(-) exchange.
在培养的兔壁细胞中，酸分泌刺激期间伴随有Na(+)/H(+)和Cl(-)/HCO(3)(-)交换激活，这可能与分泌过程中体积调节的必要性有关。我们研究了在促分泌剂刺激培养的兔壁细胞过程中是否发生细胞质体积变化。用荧光染料钙黄绿素加载细胞，通过共聚焦显微镜记录限定细胞质体积内的钙黄绿素浓度。10(-5) M的福斯可林、10(-4) M的卡巴胆碱和高渗（400 mosmol）分别导致细胞质染料浓度迅速增加21±6%、9±4%和23±5%，表明细胞收缩，随后在几分钟内恢复到基线，表明调节性容积增加（RVI）。5 mM钡引起的去极化导致细胞质染料浓度降低10±2%，表明细胞肿胀，15分钟内恢复，并完全阻止了福斯可林或卡巴胆碱诱导的细胞质收缩。Na(+)/H(+)交换抑制剂略微降低了初始细胞收缩，并显著减慢了RVI，而100 microM布美他尼对这两个参数均无显著影响。我们得出结论，酸促分泌剂诱导壁细胞细胞质体积迅速减少，随后是RVI，这主要由Na(+)/H(+)和Cl(-)/HCO(3)(-)交换介导。
