Topographical differences in distribution and responsiveness of trigeminal sensitivity within the human nasal mucosa

Abstract

The study was designed to provide a topographical map of the sensitivity of the human nasal respiratory epithelium towards trigeminal chemosensory stimuli. As an electrophysiological measure of intranasal trigeminal activation at the level of the epithelium, we used the so-called negative mucosa potential (NMP), a measure that represents the sum of generator potentials of trigeminal receptor neurons after chemical stimulation. Sixty subjects participated (30 men and 30 women; mean age 23.5 years). Measurements were made in response to stimulation with menthol, CO(2), ethanol, and cinnamaldehyde, which are known to activate trigeminal receptors to various degrees. Recordings of the NMP were made from five intranasal sites: the anterior septum, the posterior septum, the tip of the middle turbinate, the tip of the lower turbinate, and the lateral side wall of the posterior nasal cavity. The recording electrode was positioned under endoscopic control. The largest NMP amplitudes were recorded at the anterior septum in response to stimulation with CO(2). Comparing all recording sites, significant differences were observed between responses at the posterior septum and the lateral side wall of the posterior nasal cavity in response to stimulation by ethanol, menthol, and CO(2). These findings suggest that the presence of topographical and chemosensory differences in the responsiveness of the nasal mucosa to irritants.

Perceiving Nasal Patency through Mucosal Cooling Rather than Air Temperature or Nasal Resistance

“…Thus, the sensitivity to butanol may only partially reflect trigeminal sensitivity to heat loss. Mapping of mucosal sensitivity to menthol (similar to [23], [24]) or to well-controlled air puffs or temperature probes might yield more robust correlations with patency. However, any experimental design that involves exposure to menthol or eucalyptol (another TRPM8 ligand) must carefully address their cumulative anesthetic and desensitizing effects, the complications of which prevented us from using them in this pilot study, but they could be included in future studies.…”

Estimates of nasal airflow at the nasal cycle mid-point improve the correlation between objective and subjective measures of nasal patency

“…Our group proposed that mucosal cooling should be quantified as the surface area stimulated by mucosal cooling (Sullivan et al, 2014). This is based on experimental data suggesting that menthol-sensitive cold-receptors are uniformly distributed on the nasal mucosa (Liu et al, 2015; Meusel et al, 2010). In our previous study of 10 NAO patients with symmetrical mucosal engorgement in both the pre- and post-surgery CT scans, we found that the surface area where heat flux exceeds 50 W/m 2 (SAHF50) had the strongest correlation with patency scores.…”

Bubble dynamics in various commercial sparkling bottled waters

“…Carbonation, or the perception of dissolved CO 2 , indeed involves a truly very complex multimodal stimulus (Lawless and Heymann, 2010). During carbonated beverage tasting, dissolved CO 2 acts on both trigeminal receptors (Dessirier et al, 2000;Kleeman et al, 2009;Meusel et al, 2010), and gustatory receptors, via the conversion of dissolved CO 2 to carbonic acid (Chandrashekar et al, 2009;Dunkel and Hofmann, 2010), in addition to the tactile stimulation of mechanoreceptors in the oral cavity (through bursting bubbles). More recently, Wise et al (2013) showed that the carbonation bite was rated equally strong with or without bubbles under normal or higher atmospheric pressure, respectively.…”