Effect of ion transport and carbonic anhydrase inhibition on parotid salivary

In kangaroos, parotid gland secretion has >90% dependence on carbonic anhydrase activity whereas the mandibular gland secretion has >90% dependence on transport of chloride by the triple symport. Unlike kangaroos, parotid salivary [bicarbonate] in wombats is essentially constant over the whole flow range and exceeds [chloride] except at peak flow. Consequently, saliva formation by the wombat parotid gland could be initiated by acinar HCO3 secretion as in the kangaroo parotid followed by substantial ductal exchange of HCO3 for Cl or by Cl transport using the Na-K-2Cl cotransporter and/or the coupled antiports (Na/H and Cl/ HCO3) as in eutherian salivary glands. This study uses blockers of the Na-K-2Cl symport , the Cl/ HCO3 antiport, the Na/H antiport and carbonic anhydrase activity to assess the contribution of the above mechanisms to parotid saliva formation in wombats

在袋鼠体内，腮腺分泌液的活性有90%以上依赖于碳酸酐酶（carbonic anhydrase）活性，而下颌腺分泌液则有90%以上依赖于三重同向转运体（triple symport）对氯离子的转运过程。与袋鼠不同，袋熊腮腺唾液中的碳酸氢根浓度在整个分泌流量范围内基本保持恒定，且在峰值流量之前均高于氯离子浓度。因此，袋熊腮腺唾液的生成机制存在两种潜在路径：其一与袋鼠腮腺一致，由腺泡细胞分泌碳酸氢根启动唾液生成，随后发生大量碳酸氢根与氯离子的导管内交换；其二则类似真兽类唾液腺，通过钠-钾-2氯同向转运体（Na-K-2Cl cotransporter）以及/或钠氢反向转运体（Na/H antiport）、氯碳酸氢根反向转运体（Cl/HCO3 antiport）完成氯离子转运过程。本研究使用钠-钾-2氯同向转运体、氯碳酸氢根反向转运体、钠氢反向转运体的阻断剂以及碳酸酐酶抑制剂，以评估上述各类机制对袋熊腮腺唾液生成的贡献。