Na+ and K+ concentration of rat parotid saliva. Comparison of carbachol and auriculo-temporal stimulation.

The effects of carbachol and auriculo-temporal stimulation on the Na+ and K+ concentrations of rat parotid saliva have been compared. The main duct perfused in situ, does not transport Na+ or K+ and is water impermeable. The Na+ concentration of secretion evoked by either stimulus is flow dependent, increasing with increasing flow rate and plateauing at near plasma Na+ levels. At low flow rate the carbachol evoked secretion has a higher Na+ concentration. This is not due to the release of catecholamines since neither sympathectomy nor adrenoceptors block altered the nature of the secretion. The K+ concentration, whilst flow dependent, decreasing with increasing flow rate, was the same for both stimuli.