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Published on: April 21, 2014
Intrinsic H(+) ion mobility in the rabbit ventricular myocyte
R D Vaughan-Jones1, B E Peercy, J P Keener
1University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, UK. richard.vaughan-jones@physiol.ox.ac.uk
The Journal of Physiology
|May 17, 2002
Summary
Intracellular H(+) ion mobility in rabbit ventricular myocytes is slow, suggesting diffusion via mobile buffers. This movement is not significantly affected by Na(+)-H(+) exchange inhibition.
Area of Science:
- Cell Physiology
- Biophysics
- Cardiac Electrophysiology
Background:
- Understanding intracellular proton (H+) mobility is crucial for cellular function.
- Previous studies have not fully elucidated the mechanisms governing H+ movement within cardiac myocytes.
Purpose of the Study:
- To investigate the intrinsic mobility of intracellular H+ ions in rabbit ventricular myocytes.
- To determine the diffusion coefficient and movement dynamics of H+ within the cell.
- To explore the role of mobile buffers in intracellular H+ transport.
Main Methods:
- Confocal imaging of carboxy-SNARF-1 loaded rabbit ventricular myocytes.
- Controlled diffusion of acid (pH 3.0) into cells via patch pipette.
- Measurement of longitudinal H+ movement and intracellular pH (pH(i)) gradients.
- Inhibition of sarcolemmal Na+-H+ exchange using amiloride.
Main Results:
- Intracellular H+ mobility was low, with a movement time of 20-30 s over 40 microm.
- Amiloride treatment did not affect the H+ movement time, indicating minimal Na+-H+ exchange involvement.
- A longitudinal pH(i) gradient of up to 0.4 pH units was observed.
- Apparent diffusion coefficient for H+ (D(H)(app)) was 3.78 x 10(-7) cm(2) s(-1), significantly lower than in dilute solutions.
- The fluorophore SNARF had a negligible effect on H+ movement.
Conclusions:
- Intracellular H+ movement occurs via diffusive shuttling on mobile buffers.
- Mobile buffers constitute approximately half of the myocyte's buffering capacity.
- The apparent diffusion coefficient for intracellular mobile buffers (D(mob)) is ~9 x 10(-7) cm(2) s(-1).
