ABSTRACT
Proteoglycans (PGs) and glycosaminoglycans (GAGs) are an integral part of the lung extracellular matrix (1). They subserve a number of different biological functions (2). Recently, data have accumulated demonstrating that these molecules play an important role in determining the viscoelastic properties of the lung parenchyma (3), much as has been shown for other tissues, such as cartilage (4,5). In addition, proteoglycan metabolism is affected by mechanical strain, and the lung is an organ that is constantly subject to varying mechanical stresses (6,7). The purpose of this chapter is to describe recent data that document the importance of proteoglycans in determining lung physiology, and to present evidence that production of proteoglycans is affected by mechanical strain. These observations may have important implications for various lung diseases in which alterations in PGs contribute to abnormal physiology and in which altered mechanical strain is a potential pathologic mechanism.
