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Abstract
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