The stimulus-secretion coupling of glucose-induced insulin release. XLIII. Na-Ca countertransport mediated by pancreatic islet native ionophores.
Native ionophores extracted from isolated pancreatic islets were able to transport Ca2+ from one aqueous medium into another across an organic immiscible phase. In the presence of a K+, Na+, Li+, or H+ gradient, Ca2+ was transported against its own concentration gradient from the medium of low monovalent-cation concentration to the opposite medium. The transport of Ca2+ was abolished by the organic calcium-antagonist suloctidil. These findings provide a model for the process of Na-Ca countertransport in islet cells and its inhibition in response to the conversion of nutrient secretagogues to their acidic metabolites.
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D008094:Lithium / Q000378:metabolism; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013468:Suloctidil / Q000494:pharmacology
D007476:Ionophores; D008094:Lithium; D012964:Sodium; D011188:Potassium; D002118:Calcium; D013468:Suloctidil