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

Journal article

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.

Authors: Hellman, B; Andersson, T; Berggren, P; Rorsman, P

• Publication status: Published
• Journal: Biochemical medicine
• Volume: 24
• Issue: 2
• Pages: 143-152
• Publication date: 1980-10-01
• DOI: 10.1016/0006-2944(80)90005-8
• EISSN: 1557-7996
• ISSN: 0006-2944
• Language: English
• Keywords: Animals; Islets of Langerhans; Mice; Sodium; Choline; Calcium; Kinetics; Sucrose; Glucose; Subcellular Fractions; Lithium; Mice, Obese