Intravesicular glucose modulates magnesium2+ transport in liver plasma membrane from streptozotocin-treated rats.
Plasma membrane vesicles purified from livers of 4-week-old streptozotocin-injected diabetic rats present an increased basal and cation-stimulated magnesium (Mg)2+ transport as compared with vesicles purified from age-matched nondiabetic animals. Furthermore, diabetic basolateral membranes are unable to accumulate extravesicular Mg2+ in exchange for intravesicular sodium (Na)+. Loading diabetic vesicles with varying concentrations of D-glucose, in addition to Mg2+, renormalizes basal and Na+- or calcium (Ca)2+-induced Mg2+ extrusion in a dose-dependent manner, but does not restore Na+/Mg2+ exchanger reversibility. A similar effect on Mg2+ extrusion is observed when D-glucose is replaced with 2-deoxy-glucose, amylopectin, or glycogen. The loading with 3-methyl-O-glucose or L-glucose, instead, affects basal and Na+-dependent Mg2+ extrusion, but not Ca2+-dependent Mg2+ fluxes. In contrast, loading the vesicles with hexoses other than glucose or varying extravesicular glucose concentration from 5 to 20 mmol/L does not modify basal or cation-stimulated Mg2+ fluxes. Taken together, these data indicate that basal and cation-stimulated Mg2+ transport across the hepatocyte plasma membrane is altered under diabetic conditions as a result of a decrease in intravesicular (intracellular) glucose.
Cefaratti
Christie
C
Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4970, USA.
Romani
Andrea
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D000687:Amylopectin / Q000494:pharmacology; D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003847:Deoxyglucose / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000502:physiology*; D006003:Glycogen / Q000494:pharmacology; D006601:Hexoses / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism
D000963:Antimetabolites; D006601:Hexoses; D000255:Adenosine Triphosphate; D006003:Glycogen; D000687:Amylopectin; D003847:Deoxyglucose; D012964:Sodium; D008274:Magnesium; D005947:Glucose