Evidence of increased nitric oxide production in patients with the sepsis syndrome.

To investigate whether the hypotension of septic shock is due to an excess production of nitric oxide (NO), we have determined the serum levels of nitrate and nitrite (NO3/NO2), the stable end-products of NO, in 12 patients with the sepsis syndrome and marked hypotension. Compared to a mean NO3/NO2 level of 36.4 microM in controls (n = 7), the group of septic patients had a significantly elevated mean NO3/NO2 level of 124 microM (P < 0.01, Wilcoxon two-sample test). A lesser elevation was also seen in a group of postoperative patients (mean level 87.3 microM, n = 7), which was significantly elevated compared to controls (P < 0.01, Wilcoxon two-sample test), but was not significantly lower than the septic group (0.1 > P > 0.05, Wilcoxon two-sample test). These data suggest that NO may be responsible, at least in part, for the hypotension of septic shock.