Calcium and pancreatic β-cell function. XI. Modification of 45Ca fluxes by Na+ removal

B. Hellman, T. Andersson, P. O. Berggren, P. Rorsman

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Abstract

Pancreatic islets were isolated from noninbred ob/ob mice and used for evaluating how removal of extracellular Na+ affects 45Ca fluxes in the insulin-producing β cells. Isoosmotic replacement of Na+ with Li+ was less efficient in stimulating the incorporation of intracellular (La3+ nondisplaceable) 45Ca than substitution with choline+ or sucrose. Ample support for the significance of Na+-Ca2+ exchange for the net efflux of Ca2+ was obtained with the observation that Na+ deprivation markedly inhibited the 45Ca washout in a Ca2+-deficient medium. The inhibitory action of Na+ deficiency exceeded that obtained with 20 mM glucose. The 45Ca incorporated after removal of Na+ differed from that taken in response to glucose in not being exchanged with the Ca2+ entering the β cells during glucose stimulation and in appearing also in the postmicrosomal supernatant obtained by differential centrifugation.

Original languageEnglish
Pages (from-to)143-152
Number of pages10
JournalBiochemical Medicine
Volume24
Issue number2
StatePublished - Dec 1 1980
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

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Hellman, B., Andersson, T., Berggren, P. O., & Rorsman, P. (1980). Calcium and pancreatic β-cell function. XI. Modification of 45Ca fluxes by Na+ removal. Biochemical Medicine, 24(2), 143-152.