Bleakman D, Naftalin R J
Department of Physiology, King's College London, Strand, United Kingdom.
Am J Physiol. 1990 Mar;258(3 Pt 1):G377-90. doi: 10.1152/ajpgi.1990.258.3.G377.
Fluid and solute movements across rabbit distal colonic mucosa were investigated to determine the solute concentration of the absorbate and to characterize the absorption process. With isotonic mucosal and serosal bathing solutions the osmolality of the absorbate was 492 +/- 22 mosmol/kg. When the absorbate concentration was corrected for passive components of water and salt flux, the concentration of the "active" component was 1,062 +/- 206 mosmol/kg. Octanol (2 mM) caused a decrease in net solute and water absorption and in the concentration of the absorbate. Cytochalasin D (20 microM) increased the absorbate tonicity and decreased the hydraulic conductance of the active route for water movement. Correlations were made with measurements of the total crypt and crypt luminal cross-sectional areas. Ouabain, octanol, deoxycholate, and theophylline increase the cross-sectional area of the crypt lumen relative to that of the total crypt. These findings suggest that the hypertonic component of fluid absorption is via the crypts. The large osmotic pressure across the crypt wall could provide the considerable fluid tension (5 atm) required to dehydrate feces.
研究了兔远端结肠黏膜上的液体和溶质转运，以确定吸收液的溶质浓度并描述吸收过程。使用等渗的黏膜和浆膜浴液时，吸收液的渗透压为492±22毫摩尔每千克。当对水和盐通量的被动成分进行校正后，“主动”成分的浓度为1062±206毫摩尔每千克。辛醇（2毫摩尔）导致溶质和水的净吸收以及吸收液浓度降低。细胞松弛素D（20微摩尔）增加了吸收液的张力，并降低了水移动的主动途径的水力传导率。将这些结果与隐窝总横截面积和隐窝腔横截面积的测量结果进行了相关性分析。哇巴因、辛醇、脱氧胆酸盐和茶碱相对于隐窝总横截面积增加了隐窝腔的横截面积。这些发现表明，液体吸收的高渗成分是通过隐窝进行的。隐窝壁上的大渗透压可以提供使粪便脱水所需的相当大的液体张力（5个大气压）。
