Cardiac k_atp channels in health and diseases

Adenosine triphosphate (ATP)-sensitive K⁺ (K_ATP) channels were discovered in the heart almost 30 years ago. They are present in multiple tissues and link membrane excitability to the metabolic state of the cell. Under physiological conditions, cardiac K ATP channels are predominantly closed, but they may open during exertion, stress, and ischemia. Experimental and modeling studies have shown that activation of sarcolemmal K_ATP channels causes dramatic action potential shortening in vitro, which can be cardioprotective. Conversely, there is emerging evidence that K_ATP channel mutations are linked to heart diseases, including congestive heart failure and arrhythmias. The debate regarding the role, and even the very existence, of mitochondrial K_ATP channels is still ongoing. Filling these knowledge gaps will require further study, and integration of results from basic cellular electrophysiology, to animal models and clinical disease. This chapter will address the current understanding of cardiac K_ATP channels regarding molecular composition, regulation of channel activity, and physiological and pathophysiological roles.