Sellin J, Shelat H
Dept. of Internal Medicine, University of Texas Medical School Houston, USA.
J Membr Biol. 1996 Mar;150(1):83-8. doi: 10.1007/s002329900032.
SCFAs increase the volume of many different cell types rarely exposed to significant concentrations of these weak electrolytes. SCFAs swell isolated cells from colonic carcinoma cell lines, but the-mechanism(s) of volume regulation in normal colonocytes, which are generally exposed to > 100 mM SCFAs, has not been well characterized. AIMS. To determine the effect of SCFAs on volume regulation in proximal and distal rabbit colonocytes. METHODS. Isolated colonocytes were plated on coverslips and placed in a perfusion apparatus that permitted fluid changes. Cells were continuously monitored by video-microscopy; volume was estimated by measured changes in the radius of individual cells. RESULTS. Distal colonocytes (DC) consistently had a slightly greater basal volume than proximal colonocytes (PC): [14.2 pl/fl:9.8 pl/fl] In HEPES-buffered solutions, an isotonic change to a 90 mM NaCl/50 mM Na propionate solution elicited a significant increase in cell volume within 10 min, but no noticeable regulatory volume decrease over 30 min: V/Vo in DC: 1.29 +/- .09; in PC: 1.25 +/- .05. In HCO3-buffered solutions, 50 mM PROP caused significantly greater cell swelling; in DC: 1.74 +/- .21; in PC: 1.52 +/- .08. In DC both amiloride and EIPA blocked the SCFA-induced increase in cell volume. A hypotonic challenge confirmed that these cells were capable of swelling. In contrast, amiloride did not significantly inhibit SCFA-induced swelling in PC: control, 1.25 +/- .05; amiloride, 1.36 +/- .10. Cell volume increased in PC perfused with an isosmotic 50 mM propionate, Na-free solution: 1.22 +/- .04. CONCLUSIONS. (i) SCFAs induce significant cell swelling, but no regulatory volume decrease, in isolated colonocytes; (ii) HCO3 augments SCFA-induced cell swelling; (iii) volume increase in DC is dependent on Na-H exchange, but in PC appears to be Na-independent. SIGNIFICANCE. There are fundamental differences in how proximal and distal colon respond to isosmotic volume challenge of SCFAs.
短链脂肪酸（SCFAs）可增加许多不同细胞类型的体积，这些细胞类型很少暴露于这些弱电解质的显著浓度下。SCFAs可使结肠癌细胞系的分离细胞肿胀，但正常结肠细胞（通常暴露于>100 mM的SCFAs）的体积调节机制尚未得到很好的表征。目的：确定SCFAs对兔近端和远端结肠细胞体积调节的影响。方法：将分离的结肠细胞接种在盖玻片上，并置于允许液体更换的灌注装置中。通过视频显微镜持续监测细胞；通过测量单个细胞半径的变化来估计体积。结果：远端结肠细胞（DC）的基础体积始终比近端结肠细胞（PC）略大：[14.2 pl/fl:9.8 pl/fl] 在HEPES缓冲溶液中，等渗转变为90 mM NaCl/50 mM丙酸钠溶液会在10分钟内引起细胞体积显著增加，但在30分钟内没有明显的调节性体积减少：DC中的V/Vo：1.29±.09；PC中的V/Vo：1.25±.05。在HCO3缓冲溶液中，50 mM丙酸盐引起的细胞肿胀明显更大；DC中的V/Vo：1.74±.21；PC中的V/Vo：1.52±.08。在DC中，氨氯吡咪和EIPA均阻断了SCFA诱导的细胞体积增加。低渗刺激证实这些细胞能够肿胀。相比之下，氨氯吡咪在PC中并未显著抑制SCFA诱导的肿胀：对照，1.25±.05；氨氯吡咪，1.36±.10。用等渗的50 mM丙酸盐无钠溶液灌注的PC中细胞体积增加：1.22±.04。结论：（i）SCFAs在分离的结肠细胞中诱导显著的细胞肿胀，但没有调节性体积减少；（ii）HCO3增强SCFA诱导的细胞肿胀；（iii）DC中的体积增加依赖于Na-H交换，但在PC中似乎与Na无关。意义：近端和远端结肠对SCFAs等渗体积挑战的反应存在根本差异。
