Transplacental passage of a human relaxin administered to rhesus monkeys.
A synthetic version of the human relaxin encoded by the human gene 2 (hR1x-2) was administered to pregnant rhesus monkeys (Macaca mulatta) on gestational days 141-158. Monkeys (three per group) received doses of 100 micrograms/kg or 2000 micrograms/kg as a continuous i.v. infusion over 2 h into a radial vein. One monkey in the low-dose group received, along with the unlabelled hR1x-2, 25.5 microCi/kg of the test material internally labelled with [35S]cysteine. Immunoreactive hR1x-2, as measured by enzyme-linked immunosorbent assay, appeared in all fetuses within 30 min (the first sampling time) of beginning the infusions. Peak fetal plasma levels of hR1x-2 were only 0.8-1.5% of the maternal values. Only 8-15% of the fetal serum radioactivity was hR1x-2. Radioactivity from maternal urine pooled over the 4-h experiment did not elute at the volume corresponding to hR1x-2, but near the column volume.
Department of Safety Evaluation, Genentech, Inc., South San Francisco, California 94080.
P A
PA
Cossum
D E
DE
Hill
J R
JR
Bailey
J H
JH
Anderson
W
W
Slikker
D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006801:Humans; D008253:Macaca mulatta; D008431:Maternal-Fetal Exchange / Q000502:physiology*; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D012065:Relaxin / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D013462:Sulfur Radioisotopes; D013997:Time Factors
D013462:Sulfur Radioisotopes; D012065:Relaxin