Distribution and quantitation of lung parenchymal contractile tissue in ovine lentivirus-induced lymphoid interstitial pneumonia. Do tissue forces limit lung distensibility?

Lymphoid interstitial pneumonia (LIP) is frequently identified in sheep infected with the ovine lentivirus, maedi-visna virus (MVV). Functional consequences of this condition include a reduction in lung distensibility that cannot be explained by the density of surface forces within the lung parenchyma. A potential source of tissue forces to account for this functional deficit is the substantial parenchymal smooth muscle hyperplasia that is a feature of the lung pathology. This investigation examines the relationship between lung distensibility and the quantity and distribution of smooth muscle hyperplasia in MVV-induced LIP.