Objective: Activation of AMPK induces vasorelaxation in healthy arteries, but it is unknown if this response is intact in dysfunctional arteries from hypertensive animals. Here we investigate the integrity and mechanisms of AMPK-mediated relaxation in aorta from hypertensive rats. Methods: Relaxation dose- response curves to the AMPK activator 5- aminoimidazole-4-carboxamide-1-b-D- ribofuranoside (AICAR) were generated in pre- contracted aortic rings from 12 SHR and 12 Wistar-Kyoto Rats (WKY) (20-24 weeks old) using vascular myography. Area under the dose-response curves (AUC, arbitrary units) was determined as an index of relaxation. Endothelium-dependency or –independency of the responses was assessed using rings with intact (E+) or mechanically disrupted (E-) endothelium. Some rings were snap frozen before and during the AICAR dose-response curve to assess protein content and phosphorylation status. Results: Endothelium- dependent and -independent relaxation to AICAR occurred in aortic rings from SHR (AUC E+: 316±30, E-: 131±5) and WKY (AUC E+: 79±6, E-: 48±7), and responses were enhanced in SHR compared to WKY (P < 0.01 E+, P < 0.01 E-). Phospho-(Thr172)-AMPK (pAMPK) and AMPK target phospho-(Ser79)-acetyl-CoA carboxylase (pACC) were both depressed in SHR rings prior to treatment with AICAR (pAMPK/AMPK: 24±1% of WKY P < 0.01, pACC/ACC: 50±1% of WKY P < 0.05), but preliminary data indicates that AICAR treatment increases the levels of pAMPK and pACC to a greater extent in SHR vs. WKY rings relative to their respective untreated controls. Conclusions: We demonstrate for the first time that despite lower basal AMPK activation, arteries from hypertensive animals exhibit AMPK-mediated vasorelaxation and this response is more sensitive to AMPK activation in aorta from SHR vs. WKY animals. These results provide evidence that AMPK may be a useful target to improve vascular function in hypertension.