title: Dynamic NMR measurement of volume regulatory changes in Amphiuma RBC Na+ content.
abstract: 23Na nuclear magnetic resonance (NMR) and conventional chemical methods were employed to measure Na+ fluxes in Amphiuma red blood cells (RBC) during volume regulation. Paramagnetic shift reagents [dysprosium triethylenetetraminehexaacetic acid (DyTTHA) and dysprosium tripolyphosphate (Dy(TPP)2)] were used to alter extracellular Na+ magnetic resonance. Data are presented describing 23Na resonance dependence on shift reagent, sodium and calcium concentration. We confirmed that the shift reagents neither enter the cells nor alter intracellular Na+, K+, and Cl-concentrations under control conditions when extracellular calcium was maintained greater than 0.5 mM. We also confirmed that the shift reagent complexes chelate calcium [Dy(TPP)2 much more so than DyTTHA] and that their toxic effects could be alleviated by adjusting calcium in the cell's suspension medium to control levels. In parallel experiments, where volume-activated Na+ fluxes ranged from 0.3 to 3 mmol Na+/kg dry cell solid (DCS) x minute in cells containing from 30 to 150 mmol Na+/kg DCS, changes in intracellular sodium measured by 32Na NMR were within 4% of those measured by conventional destructive methods. Finally, we present data that are consistent with the interpretation that 6 mmol Na+/kg DCS plus 16% of intracellular Na+ is NMR invisible.
authors.affiliation: Department of Human Physiology, School of Medicine, University of California, Davis 95616.
authors.forename: S E
authors.initials: SE
authors.lastname: Anderson
authors.forename: J S
authors.initials: JS
authors.lastname: Adorante
authors.forename: P M
authors.initials: PM
authors.lastname: Cala
mesh_terms: D000818:Animals; D002470:Cell Survival; D003584:Cytological Techniques; D004419:Dysprosium / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D011122:Polyphosphates / Q000494:pharmacology; D012964:Sodium / Q000097:blood*; D014562:Caudata
chemical_list: D011122:Polyphosphates; D004419:Dysprosium; C048543:bis(tripolyphosphate)dysprosium(III); D012964:Sodium