Endothelin-1 mediates regional blood flow during and after pulmonary operations

To investigate the role of endothelin-1, a potent vasoconstrictor peptide produced by vascular endothelial cells, in the physiologic response to surgical stress, we measured plasma endothelin-1 concentrations by a sandwich-enzyme immunoassay in patients with lung cancer undergoing pulmonary operations (n = 12). In the first group (n = 6), we measured plasma endothelin-1 concentrations at multiple sampling sites (median cubital vein, pulmonary artery, and left atrium). Plasma endothelin-1 levels were significantly increased at all sampling sites at the end of the operation. Although there was no difference between the increased plasma levels of endothelin-1 in the pulmonary artery and in the left atrium, the increased level in the median cubital vein (peripheral venous blood) was significantly higher than that in the pulmonary artery (mixed venous blood). This result suggests that the production of endothelin-1 might differ between various organs under surgical stress. In the second group (n = 6), we measured plasma endothelin-1 concentrations both in the median cubital vein and in the ipsilateral radial artery, and also measured cardiac output and forearm blood flow. The increase in endothelin-1 levels in the median cubital vein was significantly higher than that in the radial artery after the operation. The endothelin-1 output from the forearm, calculated by the forearm blood flow and the arteriovenous difference of endothelin-1 concentrations, significantly increased after the operation. Although the cardiac output significantly increased after the operation, the forearm blood flow significantly decreased. The present findings provide a novel hypothesis that the preferential release of endothelin-1 from the peripheral vasculature of the forearm may partly contribute to a compensatory response to surgical stress, for example, the reduction of local blood flow in nonvital organs so as to increase the blood flow in vital organs.