Studies on the permeability of human oral mucosa VI. The mucosal transport of water, sodium and potassium under varying osmotic pressure

Abstract

The effect of osmotic pressure on the flow of water and on the flux of sodium and potassium through buccal and palatal mucosa has been investigated in 7 young adults by analysing the changes in weight and electrolyte content of solute-saturated discs of ash-free filter paper after mucosal contact. Solutions with an electrolyte content of 25 meq Na/1 and 25 meq K/1 and an osmolarity of 0.10—1.80 osmol/1 due to an increasing content of sucrose were employed. Linear relations between water transport and oral surface osmolarity were observed in both buccal and palatal mucosa. With solutions of low osmolarity an inflow was recorded, which gradually decreased and changed to outflow with increasing solute osmolarity. Isotony was recorded in buccal mucosa at 0.47 osmol/1 and in palatal mucosa at 1.09 osmol/1. A corresponding net flux of sodium and potassium was not registered under hypotonic and isotonic conditions. Under strong hypertony an outflux of sodium was observed from palatal mucosa as an atypical reaction in two of the persons. The observations indicated that there is no active transport of sodium through human keratinized and non-keratinized oral squamous epithelium.