Daniel H, Neugebauer B, Kratz A, Rehner G
Am J Physiol. 1985 Mar;248(3 Pt 1):G293-8. doi: 10.1152/ajpgi.1985.248.3.G293.
Considering the significance that pH value could have for digestive and absorptive processes, these investigations were aimed at precisely localizing the position of the acid microclimate, i.e., of proton accumulation along the surface of intestinal villi. The determinations were carried out under microscopic control on jejunal segments of rats incubated at 25 degrees C in O2-saturated phosphate buffer (pH 7.4). Specially manufactured antimony microelectrodes (tip diam 50 microns) and calomel reference electrodes were used for pH registration. Highest proton concentration (214-224 nmol/l not equal to pH 6.67-6.65) was found 10-100 microns below the tip of the villus in the zone of digestive and absorptive epithelial cells. Toward the crypt, a steep decrease of proton concentration was registered with alkaline values 200 microns below the villus tip. Toward the bulk phase, the decrease of the proton concentration was moderate due to the existence of the unstirred water layer as an effective diffusion barrier. The pH value of the bulk phase was reached 440 microns over the villus tip, a distance possibly identical to the thickness of the unstirred water layer.
鉴于pH值对消化和吸收过程可能具有的重要性，这些研究旨在精确确定酸性微环境的位置，即沿肠绒毛表面质子积累的位置。测定是在显微镜控制下，对在25℃下于饱和氧气的磷酸盐缓冲液（pH 7.4）中孵育的大鼠空肠段进行的。使用特制的锑微电极（尖端直径50微米）和甘汞参比电极进行pH值记录。在消化和吸收上皮细胞区域，在绒毛尖端下方10 - 100微米处发现了最高质子浓度（214 - 224纳摩尔/升，相当于pH 6.67 - 6.65）。朝着隐窝方向，在绒毛尖端下方200微米处记录到质子浓度急剧下降，出现碱性值。朝着主体相方向，由于存在作为有效扩散屏障的未搅动水层，质子浓度下降较为平缓。在绒毛尖端上方440微米处达到主体相的pH值，这个距离可能与未搅动水层的厚度相同。
