MacLeod R J, Lembessis P, Hamilton J R
McGill University-Montreal Children's Hospital Research Institute, Quebec, Canada.
Am J Physiol. 1994 Sep;267(3 Pt 1):G387-92. doi: 10.1152/ajpgi.1994.267.3.G387.
To determine the effect of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) on the isotonic volume of jejunal crypt epithelial cells, we isolated these cells by sequential perfusion using a hyperosmolar Ca(2+)-free solution and measured cell volume electronically. 8-BrcAMP caused rapid shrinkage to a reduced but stable cell volume; this isotonic volume reduction was prevented by either a Cl(-)-channel blocker, anthracene-9-carboxylate (A-9C), or Ba2+, a K(+)-channel blocker. 8-BrcAMP substantially increased the rate of A-9C-sensitive 36Cl efflux from crypt cells; this increased rate of efflux was not influenced by Ba2+ but was abolished by alterations in membrane potential. Following 8-BrcAMP-stimulated isotonic volume reduction, addition of either Ba2+ or A-9C caused the crypt cells to reswell. In contrast, 8-BrcAMP added to enterocytes isolated from the villus compartment did not result in A-9C-sensitive volume reduction or in an increased rate of 36Cl efflux. Our data demonstrate that epithelial cells isolated from jejunal crypt compartments respond directly to cAMP with a rapid volume reduction that is paralleled by an increase in 36Cl efflux through a conductive pathway. Unlike other Cl- secretory epithelial cells, the intestinal crypt cell does not appear to regulate its volume in an isotonic medium after cAMP-induced shrinkage.
为了确定8-溴腺苷3',5'-环磷酸（8-BrcAMP）对空肠隐窝上皮细胞等渗体积的影响，我们使用高渗无钙溶液通过连续灌注分离这些细胞，并以电子方式测量细胞体积。8-BrcAMP导致细胞迅速收缩至减小但稳定的细胞体积；这种等渗体积减少可被Cl(-)通道阻滞剂蒽-9-羧酸（A-9C）或K(+)通道阻滞剂Ba2+阻止。8-BrcAMP显著增加了隐窝细胞中A-9C敏感的36Cl外流速率；这种增加的外流速率不受Ba2+影响，但被膜电位改变所消除。在8-BrcAMP刺激等渗体积减少后，添加Ba2+或A-9C会使隐窝细胞再膨胀。相反，添加到从绒毛区分离的肠上皮细胞中的8-BrcAMP不会导致A-9C敏感的体积减少或36Cl外流速率增加。我们的数据表明，从空肠隐窝区分离的上皮细胞对cAMP直接产生反应，细胞体积迅速减少，同时通过传导途径的36Cl外流增加。与其他Cl-分泌上皮细胞不同，肠隐窝细胞在cAMP诱导的收缩后，似乎不会在等渗介质中调节其体积。
