Calcium and pancreatic β-cell function XI. Modification of 45Ca fluxes by Na+ removal
1980; Academic Press; Volume: 24; Issue: 2 Linguagem: Inglês
10.1016/0006-2944(80)90005-8
ISSN1557-7996
AutoresBo Hellman, Tommy Andersson, Per‐Olof Berggren, Patrik Rorsman,
Tópico(s)Diabetes and associated disorders
ResumoAbstract Pancreatic islets were isolated from noninbred ob ob mice and used for evaluating how removal of extracellular Na + affects 45 Ca fluxes in the insulin-producing β cells. Isoosmotic replacement of Na + with Li + was less efficient in stimulating the incorporation of intracellular (La 3+ non-displaceable) 45 Ca than substitution with choline + or sucrose. Ample support for the significance of Na + Ca 2+ exchange for the net efflux of Ca 2+ was obtained with the observation that Na + deprivation markedly inhibited the 45 Ca washout in a Ca 2+ -deficient medium. The inhibitory action of Na + deficiency exceeded that obtained with 20 m m glucose. The 45 Ca incorporated after removal of Na + differed from that taken in response to glucose in not being exhanged with the Ca 2+ entering the β cells during glucose stimulation and in appearing also in the postmicrosomal supernatant obtained by differential centrifugation.
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