SORE THROAT FOLLOWING NASAL AND OROPHARYNGEAL BRADYKININ CHALLENGE

Nasal challenge with bradykinin has been previously reported to cause sore throat. The aim of the present study was to investigate the mechanism of sore throat by comparing the effects of nasal and oropharyngeal challenge with bradykinin on the sensation of sore throat. Twelve healthy volunteers (6 male, 6 female, mean age 29.9 years), were given nasal followed by oropharyngeal challenge with bradykinin. The nasal and oropharyngeal challenges were separated by 1 week and 1 mg of bradykinin dissolved in 10% ethanol in 0.9% saline was administered as a spray to both nasal passages or to the posterior oropharyngeal wall and tonsillar fauces. The same group of volunteers were also given a control nasal challenge with the ethanol/saline vehicle. Subjects were asked to score symptoms of throat irritation using a ten point visual analogue scale with the extremes labelled 'Worst ever throat irritation' and 'No throat irritation', before and at intervals after bradykinin challenge. Nasal challenge with vehicle did not cause any throat irritation, but both nasal and oropharyngeal challenge with bradykinin caused a significant increase in throat irritation scores at 5 and 15 min following challenge when compared with baseline scores. At 30 min following challenge, the throat irritation scores obtained on nasal challenge were significantly greater than those obtained on oropharyngeal challenge. The results demonstrate that nasal challenge with bradykinin causes a sensation of sore throat which is just as intense as that caused by oropharyngeal challenge and with the sensation of sore throat persisting for a longer period on nasal challenge when compared with oropharyngeal challenge. The sensation of throat irritation on nasal challenge with bradykinin may be due to stimulation of sensory nerves in the nasopharynx. This finding may explain why sore throat is often reported as an early symptom of common cold as bradykinin generated by nasal infection would be cleared towards the nasopharynx.