Calcium antagonists and islet function. VIII. The effect of magnesium.
Mg2+ in high concentration (10 to 20 mEq/l) caused a dose-related inhibition of glucose-induced 45calcium net uptake and subsequent insulin release in isolated islets. Experiments performed with the isolated perfused pancreas indicated that the inhibitory effect of Mg2+ upon insulin secretion was rapid and reversible. Although excess Mg2+ reduced lactate production by the islets, the process of glucose recognition by the B-cell was apparently unaltered as judged by the inhibitory effect of the hexose upon 45calcium efflux from perifused islets and the resultant accumulation of 45calcium in the islets. Mg2+ in high concentration failed to facilitate 45calcium efflux from the islets, whether in the presence or absence of glucose. These data suggest that the major effect of Mg2+ upon islet function is to inhibit Ca2+ entry in the B-cell.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology*; D051381:Rats
D007328:Insulin; D008274:Magnesium; D005947:Glucose; D002118:Calcium