OBJECTIVETo study the early change of serum nitric oxide (NO) after acute heat exposure with trauma and the effect of NO on mean arterial pressure (MAP), thus to provide theoretical basis for studying the mechanism of NO effect in acute stress.

METHODSThe rabbit model of acute heat exposure combined with trauma was established. The animals were divided into four groups, including control, trauma, hyperthermia and hyperthermia combined with trauma. The levels of NO were measured at different time points: 0 h, 1 h, 2 h and MAP was monitored throughout the whole experiment.

RESULTSThe concentration of NO declined at first and then increased at 1 h or so after acute heat exposure and trauma. The levels of NO in hyperthermia with trauma group at 1 h, 2 h were (42.75 +/- 8.24), (59.54 +/- 9.05) micro mol/L respectively (P < 0.05), while those in control group were (56.63 +/- 3.79) and (55.22 +/- 7.15) micro mol/L, the difference at 1h between two groups was significant (P < 0.05). Under the circumstance of hyperthermia and trauma, the level of MAP declined to the lowest point at 60 - 70 min and then showed a transient rise, after that, the level declined rapidly.

CONCLUSIONSAt the early stage of acute heat exposure and trauma, the concentration of serum NO declined at first and then increased, and had certain relationship with the change of MAP.