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FOR IMMEDIATE RELEASE
August 15, 2007
APS Contact
Donna Krupa
Office:
(301) 634-7253
Cell: (703) 967-2751
dkrupa@the-aps.org
Gender, Coupled With
Diabetes, Affects Vascular Disease Development
New
study finds sex-related changes in vascular activity in diabetic animals
Austin, TX – Diabetes is associated with the
development of vascular (blood vessel) disease. As we age, vascular disease
becomes more common. It has been thought that females may be more
susceptible to the earlier development of vascular disease, as vascular
changes are observed in females long before any significant development
occurs in males. Now, a team of Georgetown University researchers has
determined that the vascular activities in diabetic animals vary according
to sex. This discovery may eventually have implications for the way males
and females are treated medically in the future.
The study, entitled “Sex Differences in Response to
Vasoactive Substances in Early Uncontrolled Diabetes,” was conducted by Adam
Mitchell, Adam Myers and Susan Mulroney, all of the Department of Physiology
and Biophysics, Georgetown University, Washington, DC. Mr. Mitchell
presented the status of the team’s findings at the conference, Sex and
Gender in Cardiovascular-Renal Physiology and Pathophysiology.
The meeting, sponsored by the American Physiological Society (APS;
www.The-APS.org), was held August 9-12, 2007 in Austin, TX.
The Study
The researchers examined the notion that very early
changes in artery activity exists in diabetic animals and differ by sex. To
test their hypothesis they divided adult male and female rats into three
groups. The first group (control) received no treatment.
The second group received
streptozotocin (STZ) to induce diabetes. The third group received STZ
plus growth hormone (GH), which is thought to exacerbate disease progression
in diabetes.
After eight weeks, the vascular reactivity to
phenylephrine, which increases blood pressure, and acetylcholine, which
reduces blood pressure, was measured in the vessels from the animals.
Vascular response to these substances was also observed during exposure to
L-NAME (which blocks production of nitric oxide, a potent artery relaxer)
and neuropeptide Y (which augments the restriction of blood vessels).
The investigators found that:
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in the early stage of the disease, both male and female
diabetics experienced significant decreases in the reactivity (i.e., how
responsive the vessel is to a drug) of their blood vessels when exposed
to acetylcholine. This occurred independent of the GH injections.
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while female diabetic rats had an increased response to
phenylephrine, there was no such change among their male counterparts.
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female controls had a larger change in phenyleprine
reactivity in the presence of L-NAME than did diabetic females,
indicating that the diabetic females had a reduced level of nitric
oxide, which dilates the artery and increases blood flow.
-
diabetic males had the opposite reaction of diabetic
females when exposed to phenylephrine and L-NAME. The diabetic males
also produced more nitric oxide than did their controls.
-
all diabetic rats exposed to growth hormone showed an
increase in nitric oxide, regardless of gender.
Conclusions
The findings support the researchers’ hypothesis of the
existence of sex-related changes in vascular activity in diabetic animals.
While the production of NO is significantly altered in the diabetic rats,
the results show that gender and the presence of GH greatly contribute to
this vascular dysfunction. According to Mitchell, “These findings show the
importance of sex differences to understanding development of vascular
problems early in diabetes and has implications on potential sex-specific
therapeutic intervention.”
****
The American
Physiological Society (APS;
www.The-APS.org) has been an integral part of the scientific discovery
process since it was established in 1887. Physiology is the study of
how molecules, cells, tissues and organs function to create health or
disease.
# # #
NOTE TO EDITORS: To schedule an interview with
Mr. Mitchell, please contact Donna Krupa at 301.634.7209 (direct
dial), 703.967.2751 (cell) or
DKrupa@the-APS.org.
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