Synchronization Modulation of Na/K Pumps Induced Membrane Potential Hyperpolarization in Both Physiological and Hyperkalemic Conditions
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The capability of the synchronization modulation (SM) technique in enhancing the function of Na/K pumps has been demonstrated in various cells and tissues, including cardiomyocytes, a monolayer of cultured MDCK kidney cells, peripheral blood vessels, and frog skeletal muscles. This study characterized the membrane potential hyperpolarization induced by SM in both physiological and high [K+]o conditions on single skeletal muscle fibers. The results showed that SM could consistently induce membrane potential hyperpolarization by a few millivolts, and this hyperpolarization was not possible in the presence of ouabain. In contrast, the same electrical pulses but with random frequencies, constant frequencies, or synchronization with backward-modulation could not hyperpolarize the membrane potential. Prolonged field application and higher field intensity enhanced the effects of SM-induced hyperpolarization. Finally, the effect of SM was tested on skeletal muscle fibers incubated in a solution with high external potassium. Results showed that the SM electric field could hyperpolarize the membrane potential even if the external K+ concentration was higher than the normal, which implied the therapeutic effects of the SM electric field on the hyperkalemic situation.
KeywordsSynchronization modulation Membrane potential hyperpolarization Hyperkalemia Na/K pump
PL conducted all of the experiments and data analysis; JM developed SM pulse generator with Java program; Dr. WC developed and patented the SM technique and supervised the project.
This project was partially supported by NIH Grant No. 2R01 50785 (W.C.) and NSF Grant No. 0515787(W.C.).
Compliance with Ethical Standards
Conflict of interest
Wei Chen has a patent on the SM technique. The other authors have no conflicts of interest to declare.
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