Guest blog: Collaborator Jasna Marinovic, Assistant professor at University of Split School of Medicine
Department of Integrative Physiology
Membrane potential is one of the most basic properties of all living cells that is vital for proper cellular function and homeostasis. At rest, most cells in our body exhibit negative membrane potential, which is primarily established via continuous efflux of potassium (K+) ions through their respective channels. In excitable cells, such as cardiac myocytes, K+-channel opening affects cellular excitability, action potential frequency and duration, with resulting impact on contraction strength, ionic balance, oxygen demand, etc.
Among different subtypes of channels specialized for conducting potassium, a unique group, which is expressed at high density in membrane of cardiac cells, are the ATP-sensitive K+ (KATP) channels. Although under no-stress conditions they do not actively participate in action potential formation, their evolutionary conservation and abundance implicate their physiological importance. Indeed, the KATP channels serve as cellular metabolic sensors, opening in situations of cardiac stress and translating metabolic changes into alterations of membrane potential. Intactness of the KATP channels was shown essential for cardiac tolerance to stress and adaptations to increased workload, such as during increased blood pressure, chronic exercise, oxidative stress, as well as acute damage by cardiac ischemia. In humans, mutations in KATP channel subunits were found in a subset of patients with idiopathic heart failure and were associated with worse clinical outcome as compared to patients without the mutations.
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