Septic shock represents an important risk factor for patients critically ill. This pathology has been largely demonstrated to be a result of a myriad of events. Glucocorticoids represent the main pharmacological therapy used in this pathology.Previously we showed that ATP-sensitive potassium (KATP) channels are involved in delayed vascular hyporeactivity in rats (24 h after Escherichia coli lipopolysaccharide (LPS) injection). In LPS-treated rats, we observed a significant hyporeactivity to phenylephrine (PE) that was reverted by glybenclamide (GLB), and a significant increase in cromakalim (CRK)-induced hypotension.We evaluated the effect of dexamethasone (DEX 8 mg kg−1 i.p.) whether on hyporeactivity to PE or on hyperreactivity to CRK administration, in vivo, in a model of LPS (8 × 106 U kg−1 i.p.)-induced endotoxemia in urethane-anaesthetised rats.DEX treatment significantly reduced, in a time-dependent manner, the increased hypotensive effect induced by CRK in LPS-treated rats. This effect was significantly (P