MG2+ MODULATES THE BINDING OF [H-3] GLIBENCLAMIDE TO ITS RECEPTOR IN RAT CEREBRAL CORTICAL MEMBRANES

Radioligand binding studies were performed to determine the effect of various cations on the characteristics of [H-3]glibenclamide binding to its high-affinity receptor in rat cerebral cortex membranes. Mg2+ was shown specifically to reduce radioligand binding to membranes pretreated with 5 mM EDTA. CaCl2 enhanced [H-3]glibenclamide binding whilst MnCl2, KCl and NaCl were without significant effect. 2 mM MgCl2 induced a statistically significant rightward shift in the dissociation constant for glibenclamide obtained from both saturation and competition studies. These results suggest that Mg2+ may participate in the regulation of the sulphonylurea receptor in the rat cerebral cortex.