Coronary blood flow control is not uniform along the vascular tree and particularly between the right coronary artery and the left anterior descending artery. Resting membrane potential that contributes largely to the vascular tone is mainly regulated by K⁺ channels in coronary myocytes. In the present study, we hypothesized that right coronary artery (RCA) and left coronary artery (LCA) exhibited a cell-specific function of K⁺ channels. The net outward current was markedly greater in RCA compared to LCA cells and this difference was due to a larger 4-AP-sensitive Kv current in RCA cells, whereas the IbTx-sensitive BK_Ca current was smaller in RCA cells. To go further in the molecular identity of this Kv current, we used 50 nM Correolide which specifically blocked Kv1 family -subunits. Outward currents generated by ramp depolarization protocols were highly sensitive to correolide in both RCA- and LCA cells suggesting that Kv1 contributed for a large part to the net outward current. 4-AP-induced contractions in isolated RCA and LCA were greater than IbTx-induced contraction. Furthermore the 4-AP-induced contraction in RCA was significantly greater than that in LCA, in agreement with the electrophysiological data. Finally, the Kv1.2 -subunit but not the Kv1.5 was detected in both RCA and LCA using primary specific antibody in western blotting and immunofluorescence assay, and expression of Kv1.2 -subunit was markedly higher in RCA compared to LCA. In summary, we reported for the first time a heterogeneous function and expression of Kv1 -subunits in rat coronary myocytes isolated from RCA or LCA.