Characterization of a rapid and sensitive enzyme immunoassay (EIA) for progesterone applied to conditioned cell culture media

PGE2 increases substance P release from renal pelvic sensory nerves via activation of N-type calcium channels

Activation of renal pelvic sensory nerves by increased pelvic pressure results in a renal pelvic release of substance P that is dependent on intact prostaglandin synthesis. An isolated renal pelvic wall preparation was used to examine whether PGE2 increases the release of substance P from renal pelvic sensory nerves and by what mechanisms. The validity of the model was tested by examining whether 50 mM KCl increased substance P release from the pelvic wall. Fifty millimolar KCl produced an increase in substance P release, from 9.6 +/- 1.6 to 26.8 +/- 4.0 pg/min, P < 0.01, that was blocked by the L-type calcium blocker verapamil (10 microM). PGE2 (0.14 microM) increased the release of substance P from the pelvic wall from 8.9 +/- 0.9 to 20.6 +/- 3.3 pg/min, P < 0.01. PGE2 failed to increase substance P release in a calcium-free medium. The PGE2-induced substance P release was blocked by the N-type calcium blocker omega-conotoxin (0.1 microM) but was unaffected by verapamil. In conclusion, PGE2 increases the release of substance P from renal pelvic sensory nerves by a calcium-dependent mechanism that requires influx of calcium via N-type calcium channels.

Enzyme immunoassay for testosterone and androstenedione in culture medium from rabbit oocytes matured in vitro

Two enzyme immunoassays (EIAs) were validated to determine testosterone and androstenedione levels in culture medium (Brackett's medium with or without the addition of IGF-I, hormone and serum-free), without previous extraction, from rabbit oocytes matured in vitro. Polyclonal testosterone (C917), and androstenedione (C9111) antibodies were raised in rabbits using testosterone 3-carboxymethyloxime:BSA, and androstenedione 3-carboxymethyloxime:BSA. Horseradish peroxidase was used as label, conjugated to testosterone 3-carboxymethyloxime, and to androstenedione 6-hemisuccinate. Standard dose response curves covered a range between 0 and 1 ng/well. The low detection limits of the technique were 11.43 pg/ml for testosterone, and 2.32 pg/ml for androstenedione. Intra- and inter-assay coefficient of variation percentages were < 6.4 and < 7.1 for testosterone, and < 5.1 and < 6.3 for androstenedione, respectively (n= 10). The recovery rate of known testosterone or androstenedione concentrations added to pools of culture maturation medium samples averaged 97.58 +/- 2.11%, and 95.73 +/- 1.59%, respectively. Compared with RIA, EIA values were in close agreement for testosterone (n= 15, r= 0.96, P< 0.001), and androstenedione (n= 15, r= 0.94, P< 0.001). Culture medium samples were obtained at the end of oocyte in vitro maturation (14-16 h). Mean +/- SE culture maturation medium concentrations (ng/ml) were 1.80 +/- 0.09 and 0.52 +/- 0.01 for testosterone, and 1.70 +/- 0.04 and 0.24 +/- 0.01 for androstenedione in both the oocytes with and without cumulus cells, respectively. We concluded that our EIA is a highly sensitive and specific assay that provides a rapid, simple, inexpensive and nonradiometric alternative to RIA for determining testosterone and androstenedione concentrations in oocyte maturation culture medium.