Acinar-duct transport sites for Na⁺ and K⁺ in dog submaxillary salivary gland

¹ Department of Dental Research, Tufts University School of Dental Medicine, Boston, Massachusetts

The submaxillary gland of the dog was employed to determine the relative roles of the acini and ducts in the net transport of Na⁺ and K⁺ into saliva. Three methods were used: stop flow, with periods of 2- and 8-min occlusion; retrograde injection of mercuric chloride (0.05% concentration and 0.2 cc in vol) into each submaxillary duct system, an adaptation of the method of Nicholson; time zero studies, a collection of salivary samples from a gland which had rested for at least 30 min before stimulation. The ducts were found to resorb Na⁺ and water at all flow rates and to secrete K⁺ into the saliva. K⁺ was found to be stored in the gland. There was evidence that Na⁺ and K⁺ were either filtered from the plasma or secreted by the acini into the lumen at concentrations similar to plasma levels.