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1. Whole‐cell K+ currents activated by calcitonin gene‐related peptide (CGRP) in smooth muscle cells enzymatically isolated from rabbit mesenteric arteries were measured in the conventional and perforated configurations of the patch clamp technique. The signal transduction pathway from CGRP receptors to activation of potassium currents was investigated. 2. CGRP (10 nM) activated a whole‐cell current that was blocked by glibenclamide (10 microM), an inhibitor of ATP‐sensitive K+ channels. Elevating intracellular ATP reduced glibenclamide‐sensitive currents. CGRP increased the glibenclamide‐sensitive currents by 3‐ to 6‐fold in cells dialysed with 0.1 mM ATP, 3.0 mM ATP or in intact cells. The reversal potential of the glibenclamide‐sensitive current in the presence of CGRP shifted with the potassium equilibrium potential, while its current‐voltage relationship exhibited little voltage dependence. 3 …