Effects of Potassium on Swallowing Performance in Healthy Humans.

There is no consensus regarding the effect of potassium on swallowing initiation. In this study, we evaluated how the topical infusion of several solutions, including potassium chloride (KCl), affects involuntary swallowing initiation in humans. Hypopharyngeal fluid stimulation was an infusion of saline (154 mM sodium chloride), 154 mM KCl, and distilled water (DW) at two infusion rates (0.2 mL/min and 3.0 mL/min) for 1 min administered to 27 volunteers. Participants were instructed to swallow when ready. Electromyography (EMGs) of the suprahyoid muscles was performed to determine swallowing muscle activity. At a lower infusion rate (0.2 mL/min), the difference in the number of swallows and the time interval between two consecutive swallows were observed only between saline and DW and between saline and KCl. At a higher rate (3.0 mL/min), a difference was observed between DW and KCl; the order of facilitatory effects was KCl, DW, and saline. The area and duration, especially the peak-to-offset time, of the EMG bursts were significantly larger and longer, respectively, during voluntary swallowing than during involuntary swallowing under all conditions. Considering the differences in the effects of KCl on swallowing initiation between previous studies and ours, some methodological differences should be considered, such as infusion rate or site and the effect of taste stimulation on the central neural network. In conclusion, KCl application at lower infusion rates is not sufficient to enhance swallowing initiation beyond that evoked by water stimulation, whereas at a higher infusion rate (3.0 mL/min), it facilitates swallowing initiation via combined ionic, chemosensory, mechanical, and/or other sensory inputs.