Characterization of the process of sodium-calcium exchange in pancreatic islet cells.
Na(+)-Ca2+ exchange may play a role in Ca2+ extrusion from the pancreatic B-cell. The characteristics of the process working in its reverse mode were examined in normal rat pancreatic islet cells. Isosmotical replacement of extracellular Na+ by sucrose induced a concentration-dependent increase in 45Ca uptake, displaying a pharmacological sensitivity compatible with an uptake mediated by Na(+)-Ca2+ exchange. Glucose, up to 2.8 mM, stimulated reverse Na(+)-Ca2+ exchange. Likewise, membrane depolarization activated the process but only under raised intracellular Na+ activity. In conclusion, the B-cell Na(+)-Ca2+ exchange displays properties similar to those observed in other cells: reversibility and sensitivity to membrane potential. When working in its reverse mode the exchanger displays a quite large capacity. The role played by the exchanger in the process of insulin release warrants further investigation.
Plasman
P O
PO
Laboratory of Pharmacology, Brussels University, School of Medicine, Belgium.
Lebrun
P
P
Herchuelz
A
A
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002352:Carrier Proteins / Q000378:metabolism*; D005907:Gliclazide / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007651:Keto Acids / Q000494:pharmacology; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D009543:Nifedipine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger; D013779:Tetrodotoxin / Q000494:pharmacology
D002132:Calcium Radioisotopes; D002352:Carrier Proteins; D007651:Keto Acids; D019831:Sodium-Calcium Exchanger; D013779:Tetrodotoxin; D010042:Ouabain; D007811:Lanthanum; D000584:Amiloride; C013082:alpha-ketoisocaproic acid; D012964:Sodium; D005907:Gliclazide; D009543:Nifedipine; D005947:Glucose; D011188:Potassium; D002118:Calcium