Ionic effects on strain differences in hepatic cytosolic glucocorticoid receptor levels in mice

Ionic conditions were varied during homogenization of adult livers and during incubation of hepatic cytosol with glucocorticoid, and the effects on the detection of differences between inbred strains of mice for receptor levels were studied. When homogenized directly in 0.01 M Tris or homogenized in distilled water and then buffered to either 0.05 M Tris or 0.01 M potassium phosphate, A/J glucocorticoid receptor levels were greater than those of B10.A. However, when homogenized directly in 0.05 M Tris or buffered to 0.05 M potassium phosphate after homogenization in distilled water, A/J and B10.A had similar receptor levels. When buffered to 0.01 M Tris after homogenization in distilled water, A/J receptor levels were greater than those of B10.A but not significantly so. In Tris buffers, glucocorticoid receptor levels were higher when livers were homogenized directly in buffer than when liver homogenates were buffered after homogenization. This concentration effect is apparently due to the more rapid decay of glucocorticoid receptor in the lower molarity buffer. A reducing agent, thioglycerol, did not appear to affect either the rate of decay of the receptors or the measured level of receptor for B10.A and A/J. C57BL/6J receptor levels were measured in Tris buffers and had a similar relationship to A/J as did B10.A.