Abstract
The effects of intracellular acidification, osmotic shrinkage and ss-adrenergic stimulation on sodium transport across the membrane of lamprey (Lampetra fluviatilis) erythrocytes were investigated. Unidirectional ouabain-insensitive sodium flux, measured using radioactive 22Na, was increased markedly by intracellular acidification, to a lesser extent by osmotic shrinkage and only modestly by ss-adrenergic stimulation. Na+/H+ exchange was activated in all of these cases. However, net sodium influx (and cell swelling caused by the influx of osmotically obliged water) was seen only in cells subjected to intracellular acidification. In contrast, practically no changes in red cell pH or in water or ion (Na+, K+ and Cl-) contents were seen after osmotic shrinkage or ss-adrenergic stimulation. Calculations of the [Na+]o/[Na+]i and [H+]o/[H+]i ratios across the erythrocyte membrane suggest that the virtual lack of net sodium movements in osmotically shrunken erythrocytes is due to the absence of a driving force for net transport of these ions via the Na+/H+ exchange pathway. It also appears that, in physiological conditions, the increase in the activity of the Na+/H+ exchanger by ss-adrenergic stimulation is too small to mediate detectable net sodium transport.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
