AJP - Renal Physiology, Vol 253, Issue 5 904-F911, Copyright © 1987 by American Physiological Society
NMR monitoring of intracellular sodium in dog and rabbit kidney-tubules
Y. Boulanger, P. Vinay and M. Boulanger
Institut de Genie Biomedical, Universite de Montreal, Quebec, Canada.
23Na-nuclear magnetic resonance (NMR) was used to monitor intra- and
extracellular sodium in suspensions of dog cortical tubules, rabbit
cortical tubules, and dog thick ascending limbs. The NMR visibility of the
intracellular sodium was determined by comparing the NMR and flame
photometry results and by redistributing the sodium ions between the intra-
and extracellular compartments using the ionophore nystatin (influx) or
sodium substitution for choline in the extracellular fluid (efflux). The
intracellular sodium visibility was approximately 30% for the total sodium
and 58% for the transportable sodium. Addition of sodium to sodium-depleted
homogenates of dog renal cortex also showed a loss of visibility. The
values of the relaxation times T1 and T2 were determined but could not be
correlated with the visibility measurements. The intracellular sodium
concentration in dog cortical tubules incubated in optimal biochemical
conditions was estimated at 51 mM and was dependent on the extracellular
sodium concentration.
