Cardiovascular risk in osteopenic postmenopausal women linked to ET-1
MedWire News: The increased cardiovascular risk seen in postmenopausal women with osteopenia may be related to an increase in endothelin (ET)-1-mediated vasoconstrictor activity, show US study findings.
Osteopenia in postmenopausal women is an established predictor of adverse cardiovascular events, but few studies have looked at the mechanisms linking the two.
Brian Stauffer (University of Colorado, Boulder) and colleagues say this is the first study to determine whether postmenopausal women with osteopenia have elevated ET-1-mediated vasoconstrictor tone. They add: "Our findings represent a potentially important link between osteopenia and increased cardiovascular risk."
For the study, the researchers measured forearm blood flow responses to intra-arterial infusion of a selective ETA receptor antagonist (BQ-123; 100 nmol/min for 60 minutes) in 10 postmenopausal women with osteopenia and 12 without osteopenia aged on average 56 and 60 years, respectively.
Women with osteopenia had lumbar spine T-scores between -1.5 and -2.5, while those without osteopenia had T-scores above -1.5. All women were at least 1 year postmenopausal and had either never taken hormone replacement therapy or discontinued its use at least 1 year prior to study commencement.
At baseline, blood flow did not differ significantly between women with and without osteopenia. Following infusion of BQ-123, women with osteopenia showed a significant vasodilator response, with forearm blood flow increased by approximately 25% from baseline. In the women without osteopenia, resting forearm blood flow was not altered in response to BQ-123 infusion.
Further analysis revealed a strong inverse correlation between lumbar spine bone mineral density and vasodilator response to BQ-123.
The researchers say the findings indicate that "osteopenia is associated with increased T-1-mediated vasoconstrictor tone that is mediated via the ETA receptor." Indeed, studies have etiologically linked ET-1 vasoconstrictor activity to coronary artery disease and chronic heart failure.
Writing in the journal Bone, Stauffer et al conclude: "It is possible that increased ET-1 activity plays a mechanistic role in the development of osteopenia and osteoporosis. Future studies are necessary to establish an etiologic link between the ET-1 system and bone-density."
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By Ingrid Grasmo