Effect of glycosaminoglycan degradation on lung tissue viscoelasticity

We tested the hypothesis that matrix glycosaminoglycans contribute to lung tissue viscoelasticity. We exposed lung parenchymal strips to specific degr adative enzymes (chondroitinase ABC, heparitinase I, and hyaluronidase) and determined whether the mechanical properties of the tissue were affected. Subpleural parenchymal strips were obtained from Sprague-Dawley rats and su spended in a Krebs-filled organ bath. One end of the strip was attached to a force transducer and the other to a servo-controlled lever arm that effec ted sinusoidal oscillations. Recordings of tension and length at different amplitudes and frequencies of oscillation were recorded before and after en zyme exposure. Resistance, dynamic elastance, and hysteresivity were estima ted by fitting the equation of motion to changes in tension and length. Qua si-static stress-strain curves were also obtained. Exposure to chondroitina se and heparitinase I caused significant increases in hysteresivity, no dec rement in resistance, and similar decreases in dynamic elastance relative t o control strips exposed to Krebs solution only. Conversely, measures of st atic elastance were different in treated versus control strips. Hyaluronida se treatment did not alter any of the mechanical measures. These data demon strate that digestion of chondroitin sulfate and heparan sulfate alters the mechanical behavior of lung parenchymal tissues.