Salivary mucin: A factor in the lower prevalence of gastroesophageal reflux disease in African-Americans

OBJECTIVES: Organic and inorganic constituents of saliva have been implicat ed as protective components in the esophagus, and deficiencies in one or mo re of these factors in different races may be an important element in the p revalence of gastroesophageal reflux disease (GERD). To determine whether t here are differences in the concentration of salivary mucins between differ ent racial groups, we measured the concentration of mucous glycoprotein MG1 and mucous: glycoprotein MG2 in whole saliva of African-Americans and Cauc asians. METHODS: Whole saliva was collected from 19 African-American (four male, 15 female; mean age 34 yr, range 19-53 yr,) and 25 Caucasian (11 male, 14 fem ale; mean age 31 yr, range 20-51 yr,) volunteers under masticatory stimulat ion (1 g Parafilm, 60 strokes/min) between 11:00 AM and 12:00 noon. Total s alivary carbohydrate was measured with a periodic acid-Schiff assay and tot al protein by absorbance at 215 nm. Immunological reagents were employed to quantify MG2 in a combined enzyme-linked immunosorbent assay/enzyme linked lectin assay (ELISA/ELLA) and to quantify MG1 in a capture ELISA. RESULTS: The total carbohydrate, protein, MG1 and MG2 values were 24.4 +/- 11.9, 243.5 +/- 62.7, 21.8 +/- 13.4, and 11.6 +/- 9.5 mg% for African-Ameri cans, and the corresponding values were 23.3 +/- 9.3, 221.7 +/- 39.7, 25.7 +/- 16.2, and 10.9 +/- 8.7 mg% for Caucasians. There was no statistical dif ference for any of the parameters measured between the two groups. Furtherm ore, it was shown that no correlation existed between salivary flow rate an d the concentration of carbohydrate, protein, or salivary mucins in African -Americans and in Caucasians. These results show that flow rate did not inf luence the measured values for salivary: parameters in the two groups. CONCLUSIONS: No differences were found in the concentration of salivary muc ins MG1 and MG2 in whole saliva of African-Americans and Caucasians, and it seems unlikely that variations in mucin levels influence the prevalence of GERD in these groups. (C) 2000 by Am. Coll. of Gastroenterology.