Nitric Oxide as a Factor of Genetically Determined Resistance to Stress Damages and Adaptive Protection

August rats are more resistant to stress-induced gastric damages than Wistar rats. These interstrain differences were abolished after blockade of nitric oxide (NO) synthesis with NO-synthase inhibitor L-NNA, which indicates that NO contributes to genetically determined resistance to stress-induced injuries. Repeated treatment with L-NNA caused gastric ulceration in Wistar, but not in August rats. This is probably related to higher basal production and more intensive accumulation of NO in August rats compared to Wistar rats. Administration of L-NNA during adaptation to hypoxia suppressed its protective effects on the stomach in stress, which indicates that NO acts as the factor of adaptive protection.