As ropivacaine-induced contraction is attenuated by both endothelial NO and voltage-dependent and calcium-activated potassium channels, the magnitude of ropivacaine-induced contraction may be enhanced in patients with decreased endothelial function and impaired potassium channel function associated with hypertension and diabetes, leading to a longer duration of ropivacaine-induced analgesia [20]. The gene discussed is KCNA3; the disease is diabetes mellitus.