Gender difference in the concentration of the antioxidant uric acid in human nasal lavage.

The entire respiratory tract is continually exposed to a variety of oxidants, of which a large percentage may react within the nasal passages. In the secretions lining the human nasal cavity uric acid has been shown to be the only low molecular weight antioxidant present in abundance. Because this uric acid originates in the plasma, it is possible that factors affecting the levels of plasma uric acid will also alter the levels recovered in lavage fluids. Lavage fluid from 15 men (20-68 years) and 11 women (20-59 years) were collected using a modified Foley catheter which allowed each subject to supply a basal lavage (saline removed immediately after instillation) and an "accrued' lavage (saline left in situ for 5 min) from each nasal cavity. Lavage fluids were assayed for protein, lysozyme and uric acid. The levels of protein and lysozyme in the recovered fluids were found not to be affected by subject age or gender. Uric acid, however, was found to have a weak negative (r2 = -0.685 basal and -0.62 accrued) correlation with age in women, but no such correlation was noted in men. Also, the levels of uric acid in women (1.3 +/- 0.3 microM/L basal and 4.5 +/- 0.6 microM/L accrued) were found to be lower than those seen in men (3.1 +/- 0.6 microM/L basal and 8.4 +/- 1.3 microM/L accrued) (p = 0.0681 and 0.0394 respectively). It is concluded that women have lower levels of uric acid in lavage fluids than men, with subject age also possibly affecting lavage uric acid. It is also proposed that such factors which lead to decreased levels of uric acid may be related to individual sensitivity to inhaled oxidants such as ozone.