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This Article Full Text Full Text (PDF) All Versions of this Article: 287/5/H2352    most recent 00528.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Swietach, P. Articles by Vaughan-Jones, R. D. Search for Related Content PubMed PubMed Citation Articles by Swietach, P. Articles by Vaughan-Jones, R. D.

INNOVATIVE METHODOLOGY

Novel method for measuring junctional proton permeation in isolated ventricular myocyte cell pairs

Burdon Sanderson Cardiac Science Centre, University Laboratory of Physiology, Oxford OX1 3PT, United Kingdom

Submitted 3 June 2004 ; accepted in final form 6 July 2004

Partial exposure of single ventricular myocytes to membrane-permeant weak acids or bases, using a dual-microperfusion technique, generates large and stable intracellular pH (pH_i) gradients. In this study, we have investigated the feasibility of using the technique to estimate junctional proton permeability. This was done by recording the pH_i gradient developed across the junctional region of a pair of conjoined ventricular myocytes, isolated enzymically from a guinea pig heart when one of the cells was partially exposed to acetate or ammonium. We show that under HEPES-buffered conditions, the junctional discontinuity in the pH_i profile can be used to derive an apparent proton permeability coefficient (P_H^app). The mean P_H^app obtained was 4.45 ± 0.21·10^–4 cm/s (n = 43) at an average junctional pH_i of 7.04 ± 0.02. In the presence of the junctional inhibitor -glycyrrhetinic acid, exposure of the proximal cell to weak acid or base produced no pH_i change in the distal cell, confirming that distal changes were normally caused by acid-base flux through connexons assembled into junctional channels. The validity of the dual-microperfusion method was tested further by using a diffusion-permeation-reaction model for intracellular protons, designed to highlight possible errors in the estimates of P_H^app. Our technique for measuring P_H^app provides a useful alternative to the previous, more invasive technique of locally loading acid through a cell-attached patch pipette. The technique may provide a simple method for investigating the factors regulating cell-to-cell proton transmission.

gap junctions; dual microperfusion

This article has been cited by other articles:

				P. Swietach, K. W. Spitzer, and R. D. Vaughan-Jones pH-Dependence of Extrinsic and Intrinsic H+-Ion Mobility in the Rat Ventricular Myocyte, Investigated Using Flash Photolysis of a Caged-H+ Compound Biophys. J., January 15, 2007; 92(2): 641 - 653. [Abstract] [Full Text] [PDF]