Inhibitory effect of insulin and cytoplasmic factor(s) on brain (Na(+) + K+) ATPase.
(Na+ + K+)ATPase activity in cerebral cortex was modulated by insulin action depending on the Mg2+ concentration. Thus, in homogenates in the presence of 1-3 mM Mg2+, insulin stimulated the enzyme, whereas in the presence of 4-6 mM Mg2+ inhibition was observed. Exposure of synaptosomal membranes to the soluble fraction resulted in inhibition of ATPase activity in a dose-dependent manner. The inhibitory effect of insulin was regulated by a cytoplasmic factor in a dose-dependent manner. Similar variations to those obtained with a crude synaptosomal fraction were obtained by using a partially purified ATPase. These results indicated the importance of soluble factors in the modulation of ATPase by insulin and add more evidence in support for a role of insulin as a neuromodulator.
Catalán
R E
RE
Departamento de Biología Molecular, Universidad Autónoma de Madrid, Spain.
Martínez
A M
AM
Aragonés
M D
MD
Fernández
I
I
Miguel
B G
BG
D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D003593:Cytoplasm / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D051379:Mice; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013574:Synaptosomes / Q000187:drug effects / Q000201:enzymology*
D007328:Insulin; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium