title: Potential binding sites for relaxin in pregnant rabbits.
abstract: The purpose of this study was to identify tissues in the day 25 pregnant rabbit that bind relaxin. First, the clearance half-life of relaxin from the rabbit (n = 6) was determined by injecting 10 g porcine relaxin via the marginal ear vein. One-milliliter blood samples were collected via a cannula in the central ear artery. Samples were collected at 10- and 5-min pre-relaxin and at 1-min intervals post-relaxin injection, and the relaxin concentrations determined by radioimmunoassay. The clearance half-life was 4 min. Next, pregnant rabbits were infused with [125I]-relaxin. Control rabbits (n = 3) received 10 g radio-inert relaxin via the marginal ear vein in order to saturate endogenous receptors. Ten minutes later, 10 ng [125I]-relaxin was similarly injected. Treated rabbits (n = 3) received only [125I]-relaxin. After allowing sufficient time for clearance (24 min), a 1-mL blood sample was removed via the central ear vein. Rabbits were euthanized, tissues of maternal and fetal origin excised, and cpm/mg of tissue divided by cpm/mL of blood was determined. Differences in uptake of [125I]-relaxin between control and treated animals, using the Student paired t test, were found for the uterus (P < .05), uterine cervix (P < .03), and mammary gland (P < .05). These data suggest potential rabbit tissues with the LGR-7 receptor.
authors.affiliation: Department of Cell Biology and Neuroscience, College of Medicine, University of South Alabama, Mobile, AL 36688, USA. pfields@usouthal.edu
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Fields
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Fields
mesh_terms: D000818:Animals; D001665:Binding Sites; D005260:Female; D006207:Half-Life; D008321:Mammary Glands, Animal / Q000378:metabolism; D011247:Pregnancy / Q000378:metabolism*; D011817:Rabbits / Q000502:physiology*; D011863:Radioimmunoassay; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide / Q000378:metabolism; D012065:Relaxin / Q000378:metabolism* / Q000493:pharmacokinetics; D013552:Swine; D014599:Uterus / Q000378:metabolism
chemical_list: D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; C033395:relaxin receptors; D012065:Relaxin