FRIDAY, March 28 (HealthDay News) -- A signaling protein called
Gi plays a critical role in protecting the heart during a heart attack,
say researchers at Thomas Jefferson University in Philadelphia.
It was already known that Gi increased activity in a failing heart, but
it wasn%26#39;t clear whether the protein was helping the heart adapt to damage
or if it actually caused more heart cells to die.
In this study, the researchers created mice that lacked a working Gi
gene, simulated a heart attack, and then restored blood flow to the heart.
These mice suffered more heart damage than mice with a normally
functioning Gi gene.
"It appears that in this setting, Gi is an important protective
mechanism," team leader Walter Koch, a professor of medicine and director
of the Center for Translational Medicine at Jefferson Medical College,
said in a prepared statement.
"The heart wants to activate Gi and attempt to protect cardiac myocytes
from dying. We found that in this acute setting, heart attacks are bigger
when Gi is blocked," he said.
The study was published in the March 18 issue of
Circulation.
Gi plays an important role in intracellular signaling, similar to a
molecular switch, explained Koch. Gi is not a new drug target, but the
activation of certain receptors (such as beta-2 adrenergic receptors) that
also turn on Gi could be drug targets.
Koch said developing a "class-specific Gi inhibitor" is a vital step in
learning more about Gi%26#39;s role and behavior.
"We don%26#39;t have to worry about what the receptor we are blocking; we%26#39;re
blocking a receptor that couples with Gi. We never had the tools before to
tell if Gi activation was good or bad. We think that we can now begin to
test the role of Gi in cardiac injury," Koch said.
More information
The American Heart Association has more about heart attack.
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