Increases in pulmonary artery pressure and cardiac output due to the inhibition of nitric oxide synthesis during operative stress.

Pulmonary artery pressure (PAP), cardiac output (CO), and urinary nitrate, a stable endproduct of nitric oxide (NO), were measured pre- and postoperatively in eight patients who underwent esophagectomy for squamous cell carcinoma of the thoracic esophagus. A significant elevation of PAP and CO on the day of operation (POD 0) was accompanied by a low concentration of urinary nitrate. A reduction in PAP and CO, and an increase in nitrate to the preoperative levels, were found on PODs 2 and 3, respectively, but urinary nitrate decreased again after POD 3. Consequently, the changes in PAP and CO were closely correlated with the nitrate concentration. These results suggest that operative stress inhibited NO synthesis with a transitory induction of endogenous NO synthesis postoperatively.