Datensatz

Zusammenfassung

TRISis commonly used as a buffer in histology but also in medicine to cure metabolic
acidosis, as a gastrointestinal and diuretic drug as well as a solvent of drugs delivered in
aerosol containers. Mainly because of the application as a solvent in aerosol containers
the question arose weather TRISa ffects odor detection ability. Using operant conditioning,
male Wistar rats were trained in an air dilution olfactometer to respond to low
level concentrations (10-3 % of vapor saturation) of odorants (ethyl acetate or n-octanal)
but not to clean air. Rats mastered this task with 90-100 % correct responses. Intranasal
perfusion of the olfactory mucosa with Ringer solution did not impair detection performance.
However, intranasal perfusion with TRIS-buffer resulted in a reduced detection
performance 30 min after treatment of the olfactory mucosa to 61.4 ± 5.6 % (ethyl acetate)
and 49.3 ± 5.3 % (n-octanal) correct responses, which represent random choice
levels. Increase of odor concentration to 10-2 vol % 50 min after flushing the nasal
cavity with TRIS-buffer improved detection performance (95 % correct answers). Four
hours after treatment, the detection performance returned to pretreatment levels (90.0 ±
12.2 % ethyl acetate; 91.0 ± 10.2 % n-octanal). We conclude that TRISr educes (but not
totally inhibits) olfactory sensitivity unspecifically and reversibly probably by changing
either 1) the pH of the mucus or receptor cells and therefore the activity of enzymes in
the signaling cascade or 2) by direct interaction with the odorant ligands or the odorant
receptors. The underlying mechanisms have to be evaluated.