Calcium induced modulation of peripheral-type benzodiazepine receptors in rat kidney membranes.
The effects of Ca2+ ions on 3H-RO 5-4864 binding to the peripheral benzodiazepine receptor were examined. Preincubation of rat kidney membranes with Ca2+ at 37 degrees C produced a dose-dependent inhibition of 3H-RO 5-4864 binding. No inhibition was observed in membranes preincubated at 0 degrees C. The effect of Ca2+ was competitive in nature and was fully reversed by the addition of EGTA. At 1 mM, the maximal effect was achieved with CaCl2, whereas CoCl2 and CdCl2 had lesser effects. No other divalent cation salts examined decreased 3H-RO 5-4864 binding to rat kidney membranes. Collectively, these data demonstrate that the affinity of 3H-RO 5-4864 binding to rat kidney membranes is regulated by Ca2+ and suggest the presence of cation recognition binding sites coupled to the peripheral benzodiazepine receptor.
Instituto de Biologia Celular Facultad de Medicina, Universidad de Buenos Aires, Argentina.
D J
DJ
Calvo
J H
JH
Medina
D000818:Animals; D001570:Benzodiazepinones / Q000378:metabolism; D001665:Binding Sites; D002118:Calcium / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007668:Kidney / Q000737:chemistry*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000378:metabolism
D001570:Benzodiazepinones; D011963:Receptors, GABA-A; C028513:4'-chlorodiazepam; D002118:Calcium