Microdissected pancreatic islets of noninbredob/ob-mice were used to study ionic effects on the lanthanum-nondisplaceable45Ca2+ uptake by islet cells. Omission of Mg2+ from the incubation medium had no effect, but the45Ca2+ uptake was increased by omission of Na+ and decreased by omission of K+. Excess Mg2+ (1.2–15 mM) inhibited and excess K+ (4.7–25 mM) stimulated the45Ca2+ uptake in a concentration-dependent manner. Stimulation of45Ca2+ uptake in Na+-deficient islets was associated with an enhancement of the basal insulin release. Total abolishment of glucose-stimulated45Ca2+ uptake in K+-deficient islets did not preclude a significant secretory response to glucose. It is concluded that the lanthanum-nondisplaceable45Ca2+ uptake shows a partial correlation to insulin release.
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Hellman, B., Sehlin, J. & Täljedal, I. Effects of Na+, K+ and Mg2+ on45Ca2+ uptake by pancreatic islets. Pflugers Arch. 378, 93–97 (1978). https://doi.org/10.1007/BF00584440
- Calcium uptake
- Insulin release
- Islets of Langerhans
- Pancreatic islets