胃粘膜HCO_3~－分泌的细胞机制和调节

正常的胃粘膜上皮细胞依赖新陈代谢的过程分泌ＧＣＯ－３。它依赖于跨膜Ｎａ＋梯度和Ｎａ＋－Ｋ＋－ＡＴＰ酶的活性；也可伴随ＮａＨＣＯ３协同转运。粘膜损伤时，紧密连结被损害或上皮脱落，可增加粘膜渗透性，使ＨＣＯ－３被动转运进入胃腔。酸可刺激依赖新陈代谢的ＨＣＯ－３分泌，也可造成其被动转运．中枢神经系统参与调节胃ＨＣＯ－３分泌，迷走神经促进其分泌，而交感神经抑制其分泌。ＨＣＯ－３参与组成一个胃粘液－ＨＣＯ－３屏障，保护胃粘膜免受损伤，促进粘膜自身修复和再生。

Cell Mechanism and Regulation of Secretion of the Gastric Mucosal HCO_3~-

The epithelial cells of the intact gastric mucosa secrete HCO-3 byprocesses that depend on tissue metabolism. It depends on a transmembrane Na a gradientand Na -K -ATPase activity, and it may occur by HaCHO3 cotransport. When the gastricmucosa is damaged, the mucosal permeability is increased by effects on tight junctions andby desquamation of the epithelium, and HCO-3 will be migrated passively into the gastriclumen. The luminal acid may stimulate the metabolism - dependent HCO-3 secretion, alsomay give rise to the passive transport of HCO-3. CNS participates in the'regulation of gastricHCO, secretion. Vagus activity accelerates HCO-3 secretion, whereas sympathetic activityinhibits HCO-3 secretion. HCO-3 participates in formation of the gastric mucus - HCO-3barrier, protects the gastric mucosa from damage and accelerates repair and regeneration ofthe gastric mucosa.