Fig. 4.
A: administration of relaxin to nonpregnant rats reproduces maternal circulatory and osmoregulatory changes of pregnancy. Although there are fewer investigations to date in humans, similar, but not identical, responses to relaxin administration have been observed. B: neutralization or elimination of circulating relaxin in midterm pregnant rats precludes the gestational changes in the maternal circulation and in osmoregulation. Emerging evidence suggests that women conceiving with donor eggs who lack a corpus luteum and circulating relaxin may have attenuated gestational circulatory changes and decreases in plasma osmolality. AII, angiotensin II; CCr, creatinine clearance; PCWP, pulmonary capillary wedge pressure. See text for details and citations.