Vasodilator action of cromakalim on human mesenteric artery

Human mesenteric artery rings (1-3 mm diameter obtained from bowel resections), precontracted with KCl 80 mM, were relaxed by cromakalim (IC50 = 0.39 +/- 0.04 microM, maximum inhibition 69 +/- 2%). Cromakalim was more effective at inhibiting KCl 40 mM than KCl 80 mM. Cromakalim also inhibited contraction produced by noradrenaline, and was a more potent inhibitor of the second phase of the noradrenaline contraction than of the first phase.