Roussa E, Alper S L, Thévenod F
Department of Anatomy, Medical Faculty, University of Saarland, Homburg/Saar, Germany.
J Histochem Cytochem. 2001 Apr;49(4):463-74. doi: 10.1177/002215540104900406.
We have studied the expression and localization of several H(+) and HCO(3)(-) transporters, whose presence in the rat pancreas is still unclear. The Cl(-)/HCO(3)(-) exchanger AE2, the Na(+)/H(+) exchangers NHE1 and NHE4, and the 31-kD and 70-kD vacuolar H(+)-ATPase (V-ATPase) subunits were detected by immunoblotting and immunocytochemical techniques. Immunoblotting of plasma membranes with transporter-specific antibodies revealed protein bands at approximately 160 kD for AE2, at approximately 90 kD and approximately 103 kD for NHE1 and NHE4, respectively, and at 31 kD and 70 kD for V-ATPase. NHE1 and NHE4 were further identified by amplification of isoform-specific cDNA using RT-PCR. Immunohistochemistry revealed a basolateral location of AE2, NHE1, and NHE4 in acinar cells. In ducts, NHE1 and NHE4 were basolaterally located but no AE2 expression was detected. V-ATPase was detected in zymogen granules (ZGs) by immunogold labeling, and basolaterally in duct cells by immunohistochemistry. The data indicate that NHE1 and NHE4 are co-expressed in rat pancreatic acini and ducts. Basolateral acinar AE2 could contribute to Cl(-) uptake and/or pH regulation. V-ATPase may be involved in ZG fusion/exocytosis and ductal HCO(3)(-) secretion. The molecular identity of the ductal Cl(-)/HCO(3)(-) exchanger remains unclear.
我们研究了几种H⁺和HCO₃⁻转运体的表达和定位，它们在大鼠胰腺中的存在情况仍不清楚。通过免疫印迹和免疫细胞化学技术检测了Cl⁻/HCO₃⁻交换体AE2、Na⁺/H⁺交换体NHE1和NHE4以及31-kD和70-kD液泡H⁺-ATP酶（V-ATP酶）亚基。用转运体特异性抗体对质膜进行免疫印迹分析，结果显示AE2在约160 kD处出现蛋白条带，NHE1和NHE4分别在约90 kD和约103 kD处出现蛋白条带，V-ATP酶在31 kD和70 kD处出现蛋白条带。使用RT-PCR扩增异构体特异性cDNA进一步鉴定了NHE1和NHE4。免疫组织化学显示，AE2、NHE1和NHE4在腺泡细胞中位于基底外侧。在导管中，NHE1和NHE4位于基底外侧，但未检测到AE2的表达。通过免疫金标记在酶原颗粒（ZG）中检测到V-ATP酶，通过免疫组织化学在导管细胞的基底外侧检测到V-ATP酶。数据表明，NHE1和NHE4在大鼠胰腺腺泡和导管中共表达。腺泡基底外侧的AE2可能有助于Cl⁻摄取和/或pH调节。V-ATP酶可能参与ZG融合/胞吐作用和导管HCO₃⁻分泌。导管Cl⁻/HCO₃⁻交换体的分子身份仍不清楚。
