Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes.
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 j...
| Main Authors: | , , , , |
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| Format: | Journal article |
| Language: | English |
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2010
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| _version_ | 1826286078403805184 |
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| author | Swietach, P Camelliti, P Hulikova, A Kohl, P Vaughan-Jones, R |
| author_facet | Swietach, P Camelliti, P Hulikova, A Kohl, P Vaughan-Jones, R |
| author_sort | Swietach, P |
| collection | OXFORD |
| description | 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. |
| first_indexed | 2024-03-07T01:38:27Z |
| format | Journal article |
| id | oxford-uuid:96015ed9-7d0c-4c38-a63d-78311a299201 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T01:38:27Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | oxford-uuid:96015ed9-7d0c-4c38-a63d-78311a2992012022-03-26T23:50:03ZSpatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:96015ed9-7d0c-4c38-a63d-78311a299201EnglishSymplectic Elements at Oxford2010Swietach, PCamelliti, PHulikova, AKohl, PVaughan-Jones, RAIMS: 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. |
| spellingShingle | Swietach, P Camelliti, P Hulikova, A Kohl, P Vaughan-Jones, R Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. |
| title | Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. |
| title_full | Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. |
| title_fullStr | Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. |
| title_full_unstemmed | Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. |
| title_short | Spatial regulation of intracellular pH in multicellular strands of neonatal rat cardiomyocytes. |
| title_sort | spatial regulation of intracellular ph in multicellular strands of neonatal rat cardiomyocytes |
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