Glucocorticoid receptors in the guinea pig.
In cytoplasmic fractions of liver and kidney prepared from adrenalectomized guinea pigs, tritiated dexamethasone ([3H]DM) is bound with a very low affinity (Kd 4 degrees C greater than or equal to 2 X 10(-7) M). By competition studies, the specificity of this binding was shown to be comparable with that for [3H]DM binding to glucocorticoid receptors in other species. In addition, cytoplasmic preparations from guinea pig liver and kidney appear to inhibit the binding of [3H]DM to rat glucocorticoid receptors under a variety of experimentally determined circumstances. It is proposed that such inhibitory activity may reflect a system of [3H]DM sequestration, perhaps by metabolizing enzymes with a high combining power for glucocorticoids. Both low affinity glucocorticoid receptors and avid binding to sites of metabolism may represent additive cellular bases for the apparent corticoresistance of the guinea pig.
D000305:Adrenal Cortex Hormones / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D002415:Cats; D003593:Cytoplasm / Q000378:metabolism; D003907:Dexamethasone / Q000378:metabolism*; D004351:Drug Resistance; D005260:Female; D006168:Guinea Pigs / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D013045:Species Specificity
D000305:Adrenal Cortex Hormones; D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D003907:Dexamethasone