We propose to perform noninvasive measurements in humans, using established techniques and novel functional magnetic resonance techniques, and combine these experimental approaches with modeling studies to elucidate changes in the heterogeneity of lung mechanics and pulmonary blood flow that occur during the early stages of pulmonary interstitial edema. We will utilize a 30-degree head-down tilt (HOT) to provoke an increase in fluid content of the lung, and consequently the early stages of pulmonary interstitial edema. This model of rapid and acute change in lung fluid balance will provide a means of inducing changes in lung mechanics and the distribution of pulmonary blood flow in the periphery of the lung. We hypothesize that the alteration in the fluid balance of the lung that occurs during 30-degree HOT in humans will increase lung water, heterogeneity of lung tissue compliance in the periphery, airway resistance, and heterogeneity of pulmonary blood flow. This study has relevance for providing (1) a 6as/c understanding of how the early stages of pulmonary interstitial edema affects lung function, and (2) a model that can be used for studies relating to the diagnosis and treatment of subclinical edema. [unreadable] [unreadable]