Pinealectomy increases ouabain high-affinity binding sites and dissociation constant in rat cerebral cortex.
The effect of the pineal gland on the ouabain high-affinity binding sites (Kd = 3.1 +/- 0.4 nM, Bmax = 246.4 +/- 18.4 fmol/mg protein) in rat cerebral cortex was studied. Pinealectomy increased Bmax (940.7 +/- 42.8 fmol/mg protein) and Kd (7.6 +/- 1.5 nM) while melatonin injection (100 micrograms/kg b.wt.) counteracted these effects, restoring kinetic parameters (Kd = 1.9 +/- 0.05 nM; Bmax = 262.2 +/- 29.6 fmol/mg prot) to control values. Melatonin activity on ouabain binding in vitro did not depend upon a direct effect on the binding sites themselves. However, in competition experiments, melatonin increased binding affinity of ouabain as shown by the decreased IC50 values.
Acuña Castroviejo
D
D
Grupo de Investigación Comunicación Intercelular e Inmunología, Departamento de Fisiología, Facultad de Medicina, Granada, Spain.
del Aguila
C M
CM
Fernández
B
B
Gomar
M D
MD
Castillo
J L
JL
D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active; D002540:Cerebral Cortex / Q000502:physiology*; D008297:Male; D010042:Ouabain / Q000378:metabolism*; D010870:Pineal Gland / Q000502:physiology*; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase