Effect of chronic in vivo exposure to hypoxia on serotonin uptake by isolated rats lungs.

1. Previously, we have shown that exposure to hypoxia stimulates serotonin uptake by cultured bovine pulmonary arterial endothelial cells. 2. In the present study, lungs isolated from rats exposed to 24 h, 48 h or 14 days of hypobaric hypoxia (0.43 or 0.5 atm) manifested no alteration of serotonin uptake in comparison to lungs from normoxic controls. 3. In addition, hypoxic stimulation of serotonin uptake by cultured rat epididymal endothelial cells was much less than that occurring in bovine pulmonary artery endothelial cells. 4. We conclude that chronic hypoxia does not stimulate serotonin uptake by rat lungs exposed in vivo as it does in endothelial cells exposed in vitro.