Coronary endothelial responses of mouse microvessels to endothelium-dependent vasodilator NS309. A, Dose-dependent vasodilation of sham control mouse microvessels and vessels undergoing CP-H/R with or without RBX treatment in response to the SK channel activator NS309 (10–9-10–5 M). B, Bar graph shows vasodilation response to NS309 10–5 M. CP-H/R, Microvessels undergoing hypoxia/reoxygenation; RBX + CP-H/R, microvessels pretreated with RBX before hypoxia and reoxygenation; RBX, ruboxistaurin.