Ligand competition by progesterone and corticosterone receptors in oviducal membrane cells

PERALTA, L.; ROLDÁN OLARTE, M. Y MICELI, D. C.

Tafi del Valle, Tucuman, Argentina

Jornada; XV Jornadas Cientificas de la Sociedad de Biologia de Tucuman; 1998

Sociedad de Biología de Tucumán

LIGAND COMPETITION BY PROGESTERONA AND  CORTICOSTERONE RECEPTORS IN  OVIDUCAL MEMBRANE CELLS L. Peralta. M. Roldan y D. Miceli. INSIBIO Inst. de Biol. Fac. de Bioq.. Qca.y Farm. UNT: Chacabuco 461 (4000) S.M de Tucumán. Our previous studies indicated that progesterone and corticostcrone bound specifically to oviducal membrane cell receptors. Progesterone receptor showed a Kd = 3.03 x 10-9 M and Bmax = 3375  fmol/mg of protein, meanwhile corticosterone receptor (C) showed a Kd= 14.6 x 10-9 M and Bmax = 1779 fmol/mg of protein. In the present communication we studied the binding of 3H(P) in  the presence of different ligands namely cstradiol, progesterone,R5020, corticosterone, propranolol, fentolamine and DEES. On the other hand specific binding of 3H (C) was displaced with progesterone, corticosterone,  aldosterone and triamcinolone. AII the analog concentrations were varied from 10-10 M to 10-4M. The displacement was carried out by incubation at 4¢XC during 45 min. The results show that only progesterone and estradiol specifically displaced progesterone receptor, and that only progesterone and corticosterone acted specifically on corticosterone receptor.