Increased plasma levels of endothelin during anaphylactic shock in the guinea-pig

Intravenous injection of ovalbumin into actively and passively sensitized guinea-pig resulted in acute circulatory collapse. The plasma level of immunoreactive endothelin rose from 22 +/- 2 to 40 +/- 7 fmol/ml (n = 12, P < 0.01) and 29 +/- 5 fmol/ml (n = 12, P < 0.01) in actively and passively sensitized animals, respectively, within 5 min of antigen challenge, and it remained significantly higher in actively sensitized animals that survived for 15 min. The plasma immunoreactive endothelin level was inversely correlated with arterial blood pO2, but not with pH or pCO2, both in actively (rs = -0.585, n = 20, P < 0.05) and passively sensitized animals (rs = -0.558, n = 20, P < 0.05). When non-sensitized animals were bled (5 and 20 ml/kg body weight), the plasma immunoreactive endothelin level remained unchanged. These results suggest that the elevated plasma level of immunoreactive endothelin during anaphylactic shock is independent of hypotension, hypovolemia and respiratory insufficiency.