Villanger O, Veel T, Holthe M R, Cragoe E J, Raeder M G
University of Oslo, Institute for Experimental Medical Research, Norway.
Acta Physiol Scand. 1992 Nov;146(3):369-76. doi: 10.1111/j.1748-1716.1992.tb09431.x.
Secretin-dependent ductular HCO3- secretion into bile may involve secretion of H+ to interstitial fluid and HCO3- to bile by the ductular epithelium. To determine whether secretin causes bile ductules to secrete H+, we have examined the effect of secretin on the elimination of an intracellular acid load from bile ductular epithelium during pharmacological blockade of Na(+)-H+ exchange and in the absence of HCO3-. Microdissected bile ductules from pigs were suspended in HCO3- free HEPES buffer and loaded with acid using an NH4Cl prepulse technique. Intracellular pH was measured using dual-wavelength excitation of BCECF fluorescence. Na(+)-H+ exchange was defined as a Na(+)-dependent and amiloride- and 5-(N,N-hexamethylene)-amiloride-sensitive efflux of H(+)-ions following acid loading. We found that secretin stimulated ductular H+ secretion independent of Na(+)-H+ exchange. Blockade of Na(+)-H+ exchange by hexamethylene-amiloride did not affect secretin-dependent ductular HCO3- choleresis in vivo. We conclude that secretin stimulates bile ductules to secrete H(+)-ions to interstitial fluid as well as HCO3- ions to bile by a mechanism independent of Na(+)-H+ exchange.
促胰液素依赖性胆管细胞向胆汁中分泌碳酸氢根离子可能涉及胆管上皮细胞向细胞外液分泌氢离子以及向胆汁中分泌碳酸氢根离子。为了确定促胰液素是否会导致胆管分泌氢离子，我们研究了在药理学阻断钠氢交换以及不存在碳酸氢根离子的情况下，促胰液素对胆管上皮细胞内酸负荷消除的影响。从猪身上显微解剖得到的胆管悬浮于无碳酸氢根离子的HEPES缓冲液中，并使用氯化铵预脉冲技术加载酸。使用双波长激发BCECF荧光来测量细胞内pH值。钠氢交换被定义为在酸加载后氢离子的钠依赖性、氨氯吡脒和5-(N,N-六亚甲基)-氨氯吡脒敏感的流出。我们发现促胰液素刺激胆管分泌氢离子，且与钠氢交换无关。六甲铵对钠氢交换的阻断并不影响体内促胰液素依赖性胆管碳酸氢根胆汁分泌。我们得出结论，促胰液素通过一种独立于钠氢交换的机制刺激胆管向细胞外液分泌氢离子以及向胆汁中分泌碳酸氢根离子。
