Potassium channels are the most widely distributed type of ion channel and are found in virtually all living organisms. They form potassium-selective pores that span cell membranes. Furthermore, potassium channels are found in most cell types and control a wide variety of cell functions, such as regulation of cellular excitability, neurotransmitter release, protecting cardiac myocytes, and anti-arrhythmia function, and are involved in learning and memory process, and temperature control. Potassium channel blockers is a class of drugs that act by inhibition of potassium efflux through cell membranes, including inorganic ions (Cs, Ba) and organic molecules (TEA, 4-AP), toxins (scorpion venoms, snake venoms, and bee venoms), and potassium channel blockers in clinical use.