THE EFFECTS OF INORGANIC IONS ON THE STORAGE AND UPTAKE OF H³-NOREPINEPHRINE BY RAT HEART SLICES

¹ Laboratory of Chemical Pharmacology, National Heart Institute, National Institutes of Health, Bethesda, Maryland

The effects of various solutions of inorganic ions on the uptake and storage of H³-norepinephrine were studied in rat heart slices. Na is an absolute requirement for the uptake and storage of norepinephrine, and Na⁺-deficient media cause the release of amine. Low extracellular [K⁺] facilitates uptake and storage, whereas high extracellular [K⁺] antagonizes the effect of Na⁺ on uptake and storage. The efflux of H³-norepinephrine is increased in the absence of Ca⁺ and is further enhanced by ethylenediamine tetraacetic acid. Ouabain blocks uptake more effectively than it increases efflux. These effects of ouabain are similar to the effects of K⁺-free media, suggesting a relationship between ouabain and a K⁺-activated process. The possibility that Na⁺ is required for membrane transport as well as intracellular binding is discussed. Ouabain affects mainly the transport. The various ionic interrelationships observed for amine transport are similar to those described for amino acids and sugars. The mechanism of Nat-dependent transport is discussed in terms of existing hypotheses for the transport of sugars and amino acids by other tissues.

This article has been cited by other articles:

				J. M. Stolk, W. J. Nowack, J. D. Barchas, and S. R. Platman Brain Norepinephrine: Enhanced Turnover after Rubidium Treatment Science, April 24, 1970; 168(3930): 501 - 503. [Abstract] [PDF]