title: Development of a homologous radioimmunoassay for rat relaxin.
abstract: Highly purified rat relaxin has been radioiodinated to specific activities of approximately 100 micro Ci/microgram with the Bolton and Hunter reagent [N-succinimidyl 3-(4-hydroxy-5-[125I]iodophenyl) propionate]. A rabbit antirat relaxin serum, applicable in a final dilution of 1:100,000, was developed in a rabbit using unconjugated highly purified rat relaxin. A specific and precise double antibody RIA for rat relaxin sufficiently sensitive to routinely measure from 32--2000 pg rat relaxin was developed. Using this RIA, relaxin immunoactivity levels in extracts of pregnant rat ovaries were found to rise from 0.8 microgram/geq ovarian fresh tissue on day 8 of pregnancy to 723 microgram/geq ovarian fresh tissue on day 20 of pregnancy and then to drop precipitously to 6 microgram/geq ovarian fresh tissue on day 1 of lactation. Consistent with the occurrence and relative levels of relaxin in the ovarian extracts, levels of relaxin in pregnant rat serum were less than 2 ng/ml on day 10 of pregnancy, approximately 150 ng/ml on days 20 and 22 of pregnancy, and 12 ng/ml on day 2 of lactation.
mesh_terms: D000818:Animals; D002369:Castration; D005260:Female; D007774:Lactation; D008297:Male; D010053:Ovary / Q000032:analysis; D011247:Pregnancy; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D012065:Relaxin / Q000032:analysis* / Q000097:blood; D012737:Sex Factors; D013552:Swine
chemical_list: D012065:Relaxin