HYPOXEMIA AND RELEASE OF ENDOTHELIN-1

Background - Secretion of the vasoconstrictor peptide endothelin-1 fro m vascular endothelium is increased by various stimuli. Whether hypoxa emia affects plasma levels of endothelin-1 in humans is unknown, but t his may be important in the haemodynamic response to hypoxaemia. The p lasma endothelin-1 concentrations in hypoxaemic humans has therefore b een measured. Methods - Plasma levels of endothelin-1 were measured by specific radioimmunoassay in 10 control subjects at rest and followin g 30 minutes of acute hypoxaemia (Sao, 75-80%) induced by breathing a nitrogen/oxygen mixture, and in 10 patients with hypoxaemic cor pulmon ale. Results - The plasma endothelin-1 concentration in control subjec ts was increased from a mean (SE) of 0.90 (0.11) pmol/l at baseline to 2.34 (0.34) pmol/l during hypoxaemia. In patients with cor pulmonale the plasma endothelin-l concentration was 2.96 (0.34) pmol/l, raised i n comparison with control subjects at rest but similar to levels in co ntrols during hypoxaemia. Conclusions - Plasma levels of endothelial w ere increased by hypoxaemia in humans. The raised levels observed in p atients with cor pulmonale may largely be attributable to the effects of hypoxaemia, although the pathophysiological significance of these o bservations remains to be established.