The effect of tetracyclines on the viscoelastic properties of bronchial mucus

Non destructive creep compliance tests have been used to investigate the effects of tetracycline antibiotics on the physical properties of human bronchial mucus in vitro. Oxytetracycline, tetracycline, chlortetracycline and demethylchlortetracycline resulted in an increase in consistency of the mucus which was produced by homogenisation of the gel phase. In contrast pyrrolidinomethyltetracycline reduced the residual shear viscosity (η ₀) and increased the instantaneous shear compliance (J ₀). Neither the hydrogen ion concentration of the antibiotic solutions nor the chelation of calcium within the gel could be shown to account for the observed results. It is concluded that tetracycline-glycoprotein interactions may provide a possible explanation of the reported changes.