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Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes.

Swietach, P, Camelliti, P, Hulikova, A, Kohl, P and Vaughan-Jones, RD (2010) Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. Cardiovasc Res, 85 (4). pp. 729-738.

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AIMS: Intracellular pH (pHi), an important modulator of cardiac function, is normally regulated to within narrow limits (7.1-7.2). In adult ventricular cell pairs, localized cellular pHi disturbances are removed by sarcolemmal acid/base transporters, but can also be dissipated (diluted) across gap junctions, aboard mobile buffers such as CO2/HCO3- and histidine-containing dipeptides (HCDPs). In the present work, we test this model of spatial pHi regulation in multicellular strands of neonatal rat ventricular myocytes. METHODS AND RESULTS: We confocally image pHi (intracellular fluorescence emitted from the pH dye carboxy-SNARF-1) in multicellular (>500 microm long, approximately 30 microm wide) cultured strands of electrically coupled, neonatal rat ventricular myocytes. Activity of sarcolemmal Na+/H+ exchange and Na+-HCO3- co-transport resembles that in adult cells. Localized photolytic H+ uncaging from intracellular 2-nitrobenzaldehyde, in the presence of CO2/HCO3- buffer, triggers considerable passive H+ spread along a strand, thus helping to dissipate the acid load. Inhibition of gap junctions (with alpha-glycyrrhetinic acid) truncates the spread, indicating they are conduits for local intracellular H+ flux. Without CO2/HCO3- buffer, longitudinal H+ mobility is reduced by approximately 90%, indicating that intracellular and cell-to-cell H+ flux relies far less on intrinsic mobile buffers (e.g. HCDPs) in neonates than in adults. This is consistent with five-fold lower HCDP levels in neonatal, compared to adult, ventricular tissue, and also with measurements of a lower intrinsic (non-CO2/HCO3-) H+ buffering capacity in neonatal strands compared with freshly isolated adult cells. CONCLUSION: We conclude that mobile buffers and gap junctions are key spatial controllers of pHi in cardiac tissue, helping to maintain a myocardial pHi syncitium. In neonatal tissue, intracellular H+ movement is CO2/HCO3- dependent, while adult tissue relies increasingly on intrinsic dipeptides that provide additional spatial pHi control, appropriate for the developmental increase in myocyte size.

Item Type: Article
Divisions : Surrey research (other units)
Authors :
Swietach, P
Hulikova, A
Kohl, P
Vaughan-Jones, RD
Date : 1 March 2010
DOI : 10.1093/cvr/cvp343
Uncontrolled Keywords : Acid-Base Equilibrium, Animals, Bicarbonates, Buffers, Carbon Dioxide, Cell Communication, Cells, Cultured, Diffusion, Dipeptides, Gap Junctions, Heart Ventricles, Histidine, Hydrogen-Ion Concentration, Microscopy, Confocal, Models, Biological, Myocytes, Cardiac, Rats, Rats, Wistar, Sarcolemma
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 17 May 2017 10:00
Last Modified : 24 Jan 2020 18:15

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