Reduced Mg2+-ATPase activity in the hypoglycemic adult rat brain.
The effects of different a-D-Glucose (Glu) concentrations (0-16 mM) on Na+, K+-ATPase and Mg2+-ATPase activities were investigated in homogenates of adult male rat whole brain at 37 degrees C. The enzyme activities were determined after 1 h preincubation with Glu. Brain Na+, K+-ATPase was not affected by Glu different concentrations. On the contrary, Mg2+-ATPase activity was considerably reduced with Glu concentrations lower than 4 mM. The enzyme was inhibited 40%, 50% or 80% with 3, 2 or 1 mM of Glu, respectively. The above results suggest: a) The various concentrations of Glu have no effect on brain Na+, K+-ATPase activity. b) The inhibited brain Mg2+-ATPase in hypoglycemia produces low intracellular Mg2+, which could modulate the activity of Mg2+-dependent enzymes and the rates of protein synthesis and growth of the cell.
Tsakiris
S
S
Department of Experimental Physiology, University of Athens, Medical School, Greece. stsakir@cc.uoa.gr
Koromilas
C
C
Schulpis
K H
KH
D000818:Animals; D001921:Brain / Q000201:enzymology*; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D007003:Hypoglycemia / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose