He X, Tse C M, Donowitz M, Alper S L, Gabriel S E, Baum B J
Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892-1190, USA.
Pflugers Arch. 1997 Jan;433(3):260-8. doi: 10.1007/s004240050276.
Immunofluorescence labelling and confocal microscopy were employed to examine the polarized distribution of several membrane transport proteins believed to be essential for salivary secretion in the rat submandibular gland. The Na+/K+-ATPase, Na+/H+ exchanger isoform 1 (NHE1), and the secretory Na+/K+/2Cl- cotransporter isoform were all found in the basolateral membranes of acinar and intralobular duct cells. Anion exchanger isoform 2 (AE2) was found only in the basolateral membranes of acinar cells, while AE1 was absent from glandular epithelial cells. Aquaporin 5 was detected in the apical membranes of acinar cells, while the cystic fibrosis transmembrane conductance regulator was found only in apical membranes of intralobular duct cells. NHEs 2 and 3 were found in the apical membranes of both acinar and intralobular duct cells. Our results are generally consistent with the expected distribution of most transporters based on previous physiological and pharmacological experiments. However, the apical localization of NHEs 2 and 3, and the presence of the secretory isoform of the Na+/K+/2Cl- cotransporter in intralobular duct cells were not predicted.
采用免疫荧光标记和共聚焦显微镜检查几种膜转运蛋白在大鼠下颌下腺中的极化分布，这些蛋白被认为对唾液分泌至关重要。钠钾ATP酶、钠氢交换体同工型1（NHE1）和分泌型钠钾氯共转运体同工型均在腺泡和小叶内导管细胞的基底外侧膜中发现。阴离子交换体同工型2（AE2）仅在腺泡细胞的基底外侧膜中发现，而AE1在腺上皮细胞中不存在。水通道蛋白5在腺泡细胞的顶端膜中检测到，而囊性纤维化跨膜传导调节因子仅在小叶内导管细胞的顶端膜中发现。NHE2和NHE3在腺泡和小叶内导管细胞的顶端膜中均有发现。我们的结果总体上与基于先前生理和药理实验对大多数转运蛋白的预期分布一致。然而，NHE2和NHE3的顶端定位以及小叶内导管细胞中钠钾氯共转运体分泌型同工型的存在并未被预测到。
