CULTURE OF PULMONARY MICROVASCULAR SMOOTH-MUSCLE CELLS FROM INTRAACINAR ARTERIES OF THE RAT - CHARACTERIZATION AND INDUCIBLE PRODUCTION OF NITRIC-OXIDE

Pulmonary arterial microvascular smooth muscle function governs many a spects of lung physiology and pathophysiology. Acutely, microvascular smooth muscle cells (SMC) modulate pulmonary vascular resistance; chro nically, they contribute to vascular remodeling. Recent work has also suggested a possible immune function for pulmonary smooth muscle throu gh cytokine-stimulated nitric oxide production. To facilitate study of the mechanisms underlying these functions, we have developed methods for isolating pulmonary arterial microvessels from the rat and culturi ng SMC from these vessels. The pulmonary arterial circulation was fill ed with a suspension of iron oxide in agar, and a subpleural tissue sa mple was obtained. The vessels were cleared of surrounding lung parenc hyma by partial collagenase digestion, and the iron-containing arterie s were separated magnetically. The diameter of the harvested arteries confirmed an intraacinar origin, and the cultured cells expressed smoo th muscle isoforms of alpha-actin and myosin but did not take up acety lated low density lipoprotein. To assess a possible immune effector ro le for these cells, confluent monolayers were stimulated with cytokine s and endotoxin. At 24 h, immunofluorescent staining for inducible nit ric oxide synthase was prominent within these cells. Nitric oxide prod uction, as measured by nitrite levels in the cell-conditioned medium, was also markedly elevated but reduced by adding N(G)-monomethyl-L-arg inine. We conclude that rat pulmonary arterial microvascular SMC can b e obtained by the iron oxide infusion method and that these cells expr ess an inducible nitric oxide synthase after cytokine stimulation.