Voluntary wheel running selectively augments insulin-stimulated vasodilation in arterioles from white skeletal muscle of insulin-resistant rats.
BACKGROUND
Exercise (RUN) prevents declines in insulin-mediated vasodilation, an important component of insulin-mediated glucose disposal, in rats prone to obesity and insulin resistance.


OBJECTIVE
Determine whether RUN (1) improves insulin-stimulated vasodilation after insulin resistance has been established, and (2) differentially affects arterioles from red and white muscle.


METHODS
Insulin signaling and vasoreactivity to insulin (1-1000 μIU/mL) were assessed in 2A from the Gw and Gr of SED OLETF rats at 12 and 20 weeks of age (SED12, SED20) and those undergoing RUN (RUN20) or caloric restriction (CR20; to match body weight of RUN) from 12 to 20 weeks.


RESULTS
Glucose and insulin responses to i.p. glucose were reduced in RUN20, elevated in SED20 (p < 0.05 vs. SED12), and maintained in CR20. Insulin-stimulated vasodilation was greater in Gw but not Gr, 2As of RUN20 (p < 0.01 vs. all groups), and was improved by ET-1 receptor inhibition in Gw 2As from SED20 and CR20 (p < 0.05). There were no differences in microvascular insulin signaling among groups or muscle beds.


CONCLUSIONS
RUN selectively improved insulin-mediated vasodilation in Gw 2As, in part through attenuated ET-1 sensitivity/production, an adaptation that was independent of changes in adiposity and may contribute to enhanced insulin-stimulated glucose disposal.
Division of Cardiology, Duke University Medical Center, Durham, North Carolina, USA.
Catherine R
CR
Mikus
Bruno T
BT
Roseguini
Grace M
GM
Uptergrove
E Matthew
EM
Morris
Randy Scott
RS
Rector
Jessica L
JL
Libla
Douglas J
DJ
Oberlin
Sarah J
SJ
Borengasser
Angelina M
AM
Taylor
Jamal A
JA
Ibdah
Maurice Harold
MH
Laughlin
John P
JP
Thyfault
D000818:Animals; D001160:Arterioles / Q000378:metabolism / Q000503:physiopathology; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology; D010805:Physical Conditioning, Animal; D051381:Rats; D020334:Rats, Inbred OLETF; D015398:Signal Transduction; D014664:Vasodilation
D007328:Insulin; D005947:Glucose