Studies on the permeability of human oral mucosa: IV. Regional changes in outflow of water from hydrated and dehydrating oral mucosa

Abstract

The discharge of water from hydrated and dehydrating oral mucosa has been investigated in 10 young adults by analysing the change in weight in standardized discs of ash-free filter paper and membrane filter after mucosal contact in a non-ventilated sampling chamber. The rate of water loss was from hydrated buccal mucosa 6.2–7.4 mg/cm²/hour and from hydrated palatal mucosa 3.0–3.6 mg/cm²/hour. Dehydration of the mucosae was achieved by creating a vapour pressure gradient to the ambient external atmosphere after suspension of the salivary secretion with scopolamine. During the first 60 minutes the water discharge showed decreasing values, followed by stabilization. A regression analysis of the relationship between time and water loss demonstrated constant values for the regression coefficients but gradually falling values for the intercept for the regression lines on the axis for the water loss, indicating a declining permeability to water due to the decreasing water content in the mucosa during dehydration. The ratio of water discharge from buccal and palatal mucosa was a constant 2:1. In the palatal mucosa local variations in water discharge were observed, probably on account of regional differences in the hydrostatic pressure. The observations are discussed in relation to ultrastructural barrier components of stratified squamous epithelium.

Key Words:

• Mouth mucosa
• biological transport
• water
• permeability