Endothelin-1 (ET-1) and human atrial natriuretic peptide (hANP) are known as vasoactive substances. In the present study, an attempt was made to evaluate the mode by which these substances are secreted in patients having severe surgical stress. Plasma ET-1 and hANP concentrations were measured in 15 patients with esophageal carcinoma who underwent subtotal esophagectomy via right-thoraco-ventrotomy (EC group) and 10 patients with gastric carcinoma who underwent total gastrectomy via ventrotomy (GC group). The volume of intraoperative hemorrhage was significantly larger and operation time was significantly longer in the EC group than in the GC group.
Plasma ET- 1 concentration in the EC group increased remarkably on the first operative day (1st POD), whereas that in the GC group did not. Plasma levels of hANP in both the EC and GC groups gradually increased until they peaked on the 2nd POD. The increment of plasma hANP secretion for the EC group was significantly higher than that for the GC group on the day of the operation, suggesting that ET-1 stimulated hANP in the EC group. Plasma hANP levels reached their peak values on the 2nd POD and returned to the preoperation level on the 5th POD, while PCWP did not change significantly after the surgery. Since this discrepancy between the postoperation patterns of PCWP and hANP cannot be explained by changes in the circulating blood volume, hANP secretion may be regulated by certain factors in addition to the left ventricular pressure experienced by patients receiving heavy operation stress, such as those in the EC group.