The effect of methacholine on nasal transmucosal potential difference in normal human subjects.

This study was proposed to test the hypothesis that the parasympathetic system might attribute to the transmucosal potential difference. In a double-blind, placebo-controlled study six volunteers had nasal transmucosal potential difference (NTPD) recorded at 4-min intervals during 12-min periods of rest, before and after treatment, as well as during exercise and recovery. Application of placebo did not significantly alter NTPD at rest. There was a significant rise during exercise (p < 0.05). The application of methacholine significantly increased NTPD at rest (p < 0.01); there was a further rise during exercise (p < 0.02). We conclude that parasympathetic stimulation can increase the transmucosal potential difference.