The effects of aspirin, ethanol, indomethacin and 9alpha-fludrocortisone on buccal mucosal potential difference.

1 Measurement of the bioelectric potential of the buccal mucosa has been made in three areas, namely on the lower lip between lip and gum, on the sublingual papilla, and at the entrance to the parotid duct. 2 The charge on the buccal mucosa (or buccal potential difference (b.p.d.)) was found to be negative with respect to a saline-injected area of skin. One hundred and eighty measurements of b.p.d. in thirty subjects demonstrated a normal distribution. B.p.d. was unchanged by stimulation of salivary flow, but was reduced or reversed in polarity over areas of aphthous ulceration. B.p.d. was reduced significantly by treatment of the mucosa with deionized water at 65°C, but not by deionized water at 20°C. A characteristic mucosal pressure artifact was demonstrated in response to an increased force applied to the mucosa through the electrode. 3 No response in salivary electrolytes, electrode measured buccal electrolytes or b.p.d. was observed after treatment with 9α-fludrocortisone. Local application of aspirin and ethanol reduced b.p.d., their effects being additive. Local application of indomethacin and deionized water produced no significant change in b.p.d. These responses to aspirin, indomethacin and ethanol are similar to the responses of gastric transmural p.d. to these agents. 4 There appear to be basic similarities in the responses of transepithelial p.d. in different areas of the upper gastrointestinal tract to agents generally regarded as damaging to mucosa.