The removal of noradrenaline in the pulmonary circulation of rat isolated lungs

Abstract

1 Removal of noradrenaline by isolated lungs of the rat, perfused via the pulmonary artery with Krebs bicarbonate solution has been studied. 2 A constant removal (40·2%) was observed over a concentration range of 2–50 ng noradrenaline/ml (12–300 nM). At 100 ng/ml (600 nM), the removal is significantly reduced to 33·5%. 3 The removal of noradrenaline was inhibited by cocaine (1 μm), but not by normetanephrine (5 μm), metaraminol (10 μm), phenoxybenzamine (10 μm) and 5-hydroxytryptamine (110 and 560 nM). 4 We conclude that the removal of noradrenaline in the lungs does not involve an uptake process comparable with those previously described for this amine. The uptake process for noradrenaline in the lung is similar to that for 5-hydroxytryptamine and may be unique to this tissue.