Synchronization modulation increases transepithelial potentials in MDCK monolayers through Na/K pumps.

Vu Tran,Hanqing Li,Wei Chen,Lin Cao,Xiaodong Zhang,Michelle So,Min Zhao,Yaohui Sun,Benjamin Lee

doi:10.1371/journal.pone.0061509

Abstract

Transepithelial potential (TEP) is the voltage across a polarized epithelium. In epithelia that have active transport functions, the force for transmembrane flux of an ion is dictated by the electrochemical gradient in which TEP plays an essential role. In epithelial injury, disruption of the epithelial barrier collapses the TEP at the wound edge, resulting in the establishment of an endogenous wound electric field (∼100 mV/mm) that is directed towards the center of the wound. This endogenous electric field is implicated to enhance wound healing by guiding cell migration. We thus seek techniques to enhance the TEP, which may increase the wound electric fields and enhance wound healing. We report a novel technique, termed synchronization modulation (SM) using a train of electric pulses to synchronize the Na/K pump activity, and then modulating the pumping cycles to increase the efficiency of the Na/K pumps. Kidney epithelial monolayers (MDCK cells) maintain a stable TEP and transepithelial resistance (TER). SM significantly increased TEP over four fold. Either ouabain or digoxin, which block Na/K pump, abolished SM-induced TEP increases. In addition to the pump activity, basolateral distribution of Na/K pumps is essential for an increase in TEP. Our study for the first time developed an electrical approach to significantly increase the TEP. This technique targeting the Na/K pump may be used to modulate TEP, and may have implication in wound healing and in diseases where TEP needs to be modulated.

Highlights

IntroductionPolarized epithelia maintain voltage differences between apical and basal sides, which are termed transepithelial potentials (TEP)
Polarized epithelia maintain voltage differences between apical and basal sides, which are termed transepithelial potentials (TEP)Transepithelial potential (TEP) represents energy consuming transport/fluxes of ions across the epithelium
MDCK monolayers established stable TEP and transepithelial resistance (TER) When MDCK form monolayer, Na/K pumps distribute to the basolateral side of the polarized epithelium

Summary

Introduction

Polarized epithelia maintain voltage differences between apical and basal sides, which are termed transepithelial potentials (TEP). TEP represents energy consuming transport/fluxes of ions across the epithelium. The sum of the membrane potentials for the basal and apical cell membranes is the TEP. The force for the transmembrane flux of ions is dictated by the electrochemical gradient. In transporting epithelia, such as in the kidney and intestines, the TEPs facilitate transport of ions, nutrients and metabolites. TEPs of 2–3 mV contribute to tubular reabsorption [1,2,3]. The thickness of the epithelial layers is about 50–70 mm, forming field strength up to 500 mV – 1000 mV/mm

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