A channel recording showing the effect of exogenous CO (10 μmol/l) alone and in conjunction with the guanylyl cyclase inhibitor ODQ (10 μmol/l) on the activity of Ca⁺⁺-activated K channels in a smooth muscle cell isolated from the rat renal interlobar artery. The experiment was performed in a cell-attached patch bathed in media without 8-bromo-cGMP. The holding potential was 0 mV. The channel closed level is indicated by C. The top recording shows the time-course of the experiment; the segments of the recording indicated by the numbers 1–3 are presented below at fast time resolution.