In 1979, Brown, DiFrancesco and Noble reported in Nature a sinoatrial current that was so unusual they felt compelled to christen it the "funny" current (If). The funny thing about this current, which is generated by the inward movement of sodium and potassium ions, is that is activated by hyperpolarization of the cell membrane. Some experts argued that this current might play a key role in the control of pacemaker activity, while other experts treated this claim with some suspicion, pointing out that it was a very small current and only one of the 10 or more currents responsible for the propagation of the nodal action potential. It certainly seemed an unlikely that If might represent a therapeutic target in the battle against cardiovascular disease. However, nowadays, as explained by Michael J. Shattock and Michael R. Rosen, this curious little channel is known to be able to exert a substantial effect upon heart rate such that its chemical inhibition may reduce cardiac rate by as much as one fifth without altering the profile of the action potential or the inotropic state of the ventricle...