Phillipson Mia, Atuma Christer, Henriksnäs Johanna, Holm Lena
Division of Physiology, Department of Medical Cell Biology, University of Uppsala, 751 23 Uppsala, Sweden.
Am J Physiol Gastrointest Liver Physiol. 2002 Feb;282(2):G211-9. doi: 10.1152/ajpgi.00223.2001.
Mucus thickness is suggested to be related to mucosal protection. We therefore investigated the importance of the removable mucous layer and epithelial bicarbonate transport in preservation of the gastric juxtamucosal pH (pH(jm)) during luminal acid. Anesthetized rats were prepared for intravital microscopy of the gastric mucosa, and pH(jm) was measured with pH-sensitive microelectrodes. The mucus was either left intact (IM) or removed (MR) down to the firmly attached mucous layer, and HCl (pH 1) was applied luminally. Removal of the loosely adherent mucous layer did not influence the pH(jm) during luminal acid (pentagastrin: IM/MR 7.03 +/- 0.09/6.82 +/- 0.19; pentagastrin + indomethacin: IM/MR 6.89 +/- 0.20/6.95 +/- 0.27; ranitidine: IM/MR 2.38 +/- 0.64/2.97 +/- 0.62), unless prostaglandin synthesis and acid secretion were inhibited (ranitidine + indomethacin: IM/MR 2.03 +/- 0.37/1.66 +/- 0.18). Neutral pH(jm) is maintained during endogenous acid secretion and luminal pH 1, unless DIDS was applied luminally, which resulted in a substantially decreased pH(jm) (1.37 +/- 0.21). Neutral pH(jm) is maintained by a DIDS-sensitive bicarbonate transport over the surface epithelium. The loosely adherent mucous layer only contributes to maintaining pH(jm) during luminal pH 1 if acid secretion and prostaglandin synthesis are inhibited.
黏液厚度被认为与黏膜保护有关。因此,我们研究了可移除的黏液层和上皮碳酸氢盐转运在管腔内酸暴露期间维持胃黏膜下pH值(pH(jm))的重要性。对麻醉大鼠进行胃黏膜活体显微镜检查,并用pH敏感微电极测量pH(jm)。黏液要么保持完整(IM),要么去除至紧密附着的黏液层(MR),然后向管腔内施加HCl(pH 1)。去除松散附着的黏液层在管腔内酸暴露期间不影响pH(jm)(五肽胃泌素:IM/MR 7.03±0.09/6.82±0.19;五肽胃泌素+吲哚美辛:IM/MR 6.89±0.20/6.95±0.27;雷尼替丁:IM/MR 2.38±0.64/2.97±0.62),除非前列腺素合成和酸分泌受到抑制(雷尼替丁+吲哚美辛:IM/MR 2.03±0.37/1.66±0.18)。在内源性酸分泌和管腔内pH值为1时,pH(jm)保持中性,除非向管腔内施加二乙氨基二硫代甲酸钠(DIDS),这会导致pH(jm)大幅下降(1.37±0.21)。中性pH(jm)通过表面上皮细胞上对DIDS敏感的碳酸氢盐转运来维持。只有在酸分泌和前列腺素合成受到抑制时,松散附着的黏液层才有助于在管腔内pH值为1时维持pH(jm)。