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

Abstract

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.