hRLX-1. In vitro response of human and pig myometrium
MacLennan, A.H.; Grant, P.; Bryant-Greenwood, G.
Journal of Reproductive Medicine 40(10): 703-706
1995
ISSN/ISBN: 0024-7758 PMID: 8551471 Document Number: 439641
Objective: To study the effect of synthetic h RLX-1 peptide on human and porcine myometrium in vitro in comparison to the effect of h RLX-2 peptide. Study Design: Myometrial strips from humans and pigs in late pregnancy were allowed to spontaneously contract in an organ bath. Muscle activity was recorded isometrically in response to varying doses of h RLX-1. Results: Synthetic h RLX-1 peptide at 0.13 mu-g/mL caused sustained and complete inhibition of pregnant pig myometrial contractility, comparable to that produced by h RLX-2 peptide, showing, for the first time, its biologic activity in this system. However, a range of concentrations of h RLX-1 peptide (0.07-7.32 mu-g/mL) had no effect on human myocardial contractions in vitro, whereas h RLX-2 peptide had some, albeit minimal, activity in this system. Conclusion: This result shows that h RLX-1 peptide does not appear to be an inhibitor of human myometrial activity and that although the pig myometrial relaxin receptor does not appear to distinguish between the two human relaxins, the human relaxin receptor might. Thus, the control of spontaneous myometrial activity during pregnancy in the human appears to be different from that in other species.