Regulating membrane potential is key to cellular function. For many animal cells, resting membrane potential is predominantly driven by a family of K2P (two-pore domain) potassium channels. These channels are commonly referred to as leak channels, as their presence results in the membrane being permeable to K ions. These channels, along with various pumps and exchangers, keep the cell resting membrane potential (Rp) relatively close to potassium's equilibrium potential (E); however, in many cells, the resting membrane potential is more depolarized than the E due to a small Na ion leak. Raising [Ca] (extracellular Ca concentration) can result in hyperpolarization of the membrane potential from the resting state. The mechanism for this hyperpolarization likely lies in the blockage of a Na leak channel (NALCN) and/or voltage-gated Na channels. The effects may also be connected to calcium-activated potassium channels. Using , we here illustrate that changing [Ca] from 0.5 to 3 mM hyperpolarizes the muscle. Replacing NaCl with LiCl or choline chloride still led to hyperpolarization when increasing [Ca]. Replacing CaCl with BaCl results in depolarization. K2P channel overexpression in the larval muscle greatly reduces the effects of [Ca] on cell membrane potential, likely because potential is heavily driven by the E in these muscles. These experiments provide an understanding of the mechanisms behind neuronal hypo-excitability during hypercalcemia, as well as the effects of altered expression of K2P channels on membrane potential.
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http://dx.doi.org/10.3390/biology13090750 | DOI Listing |
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Jiang Xi Hospital of China-Japan Friendship Hospital, Nanchang, Jiangxi, 330052, P.R. China.
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The elevated risk of cardiovascular disease (CVD) associated with inflammatory rheumatic diseases has long been recognized. Patients with established rheumatoid arthritis (RA) have a higher mortality rate compared to the general population due to abnormal platelet activation. Thymidine phosphorylase (TYMP) plays a crucial role in platelet activation and thrombosis, following bridging the link between RA and CVD.
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School of Mathematics and Statistics, University of Melbourne, Melbourne, Australia. Electronic address:
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State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032, People's Republic of China.
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