The effect of storage time and molybdate on steroid receptors in gynaecological tissues

Human female reproductive tract tissues were analysed for estrogen and progestogen receptor content in the presence or absence of sodium molybdate immediately after removal at surgery. Other fractions of the tissue were stored in liquid nitrogen and similarly analysed after 2, 4, 6 and 8 weeks storage. The results showed that at all times the apparent receptor content for both steroids was significantly higher (P less than 0.001) and Kd values were significantly lower (P less than 0.02) in assays carried out with 10 mM molybdate added to the buffer systems. Furthermore, as soon as either whole tissue or tissue cytosol was frozen for storage, receptors were "lost" with values decreasing by approximately 30% for both steroid receptors. However, once frozen in liquid nitrogen tissue receptor content remained stable over the eight weeks of study. It is recommended that laboratories standardize techniques to allow valid comparisons of results.