Is the pregnancy hormone relaxin also a vasodilator peptide secreted by the heart?
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.


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.
Department of Medicine and Therapeutics, Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, UK.
Carol
C
Fisher
Margaret
M
MacLean
Ian
I
Morecroft
Alison
A
Seed
Fiona
F
Johnston
Christopher
C
Hillier
John
J
McMurray
D000368:Aged; D001158:Arteries / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology; D012065:Relaxin / Q000378:metabolism / Q000494:pharmacology*; D014655:Vascular Resistance; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
D010455:Peptides; D014665:Vasodilator Agents; D012065:Relaxin