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Updated: May 5, 2026

Assessment of Maternal Vascular Remodeling During Pregnancy in the Mouse Uterus
Published on: December 5, 2015
Is the pregnancy hormone relaxin also a vasodilator peptide secreted by the heart?
Carol Fisher1, Margaret MacLean, Ian Morecroft
1Department of Medicine and Therapeutics, Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, UK.
Background:
It has been shown recently that the pregnancy and parturition hormone, relaxin, is secreted by the heart. This study examined the effects of relaxin in small human resistance arteries from the systemic and pulmonary circulations.
Methods And Results:
Arteries were obtained from gluteal biopsies and resected lung tissue and studied with the use of wire myography. Cumulative concentration relaxation curves were constructed in systemic arteries with substance P, epoprostenol, atrial natriuretic peptide, and relaxin (concentration range 10(-13) -10(-7)M). The maximal responses were 88(+/-5)%, 67(+/-10)%, 52(+/-16)% and 66(+/-16)%, respectively. Endothelium removal virtually abolished the action of relaxin. Relaxin had no vasodilator effect in pulmonary arteries.
Conclusions:
Relaxin is a powerful dilator of systemic resistance arteries secreted by the heart that may contribute to cardiovascular regulation.
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