PUTATIVE ESTROGEN-RECEPTORS IN RAT DUODENAL CELLS

The precise interaction of oestrogens and their receptors in relation to Ca2+ absorption in the small intestine is still unclear. The object of this investigation was therefore to investigate the presence of fu nctional oestrogen receptors in the duodenum of female BD9 rats. The c lassic radioligand binding procedure was used to ascertain the ER stat us of a crude extract of duodenal cells. After cells had been homogeni sed, a B-max of 147 fmol mg(-1) protein (SD = 14 fmol mg(-1) protein, K-d = 4.3 x 10(-10) +/- 0.8 nM) was obtained. Competition binding stud ies showed that oestradiol (E(2)) and diethylstilbestrol (DES) decreas ed the binding of [H-3]-oestradiol. The dissociation constants and rel ative affinities for E(2) and DES were 0.6 nM (97%) and 0.4 nM (78%), respectively. These results may help to elucidate the functional ER st atus of duodenal cells.