This work was done on rat tourniquet shock (ToS) model. It was found that reactivity of isolated perfused aortic ring to noradrenaline decreased, while cGMP content of the aortic tissue increased. These changes could be potentiated by perfusion with L-arginine (NO-precursor). On the other side, when the aortic ring was perfused with L-NNA (NO-synthesis inhibitor) or methylene blue (soluble cGMPase inhibitor), the changes could be attenuated. The effect of these drugs are independent of the presence of vascular endothelium. The results suggest that non-endothelium-derived NO-like relaxing factor may be one of the factors causing low vascular reactivity of the ToS animals.