Hypercholesterolemia impairs myocardial perfusion and permeability: role of oxidative stress and endogenous scavenging activity.
OBJECTIVE
We intended to study the effect of hypercholesterolemia (HC) on myocardial perfusion and permeability response to increased cardiac demand.


BACKGROUND
Hypercholesterolemia is associated with increased incidence of cardiac events and characterized by impaired coronary vascular function, possibly mediated partly through increased pro-oxidative conditions in plasma and tissue. However, it is yet unclear whether HC is also associated with impaired myocardial perfusion and vascular permeability responses in vivo.


METHODS
For 12 weeks pigs were fed a normal, HC or HC diet supplemented daily with antioxidants (HC + AO, 100 IU/kg vitamin E and 1 g vitamin C). Myocardial perfusion and vascular permeability were measured in vivo using electron beam computed tomography before and after cardiac challenge with intravenous adenosine. Plasma and tissue oxidative status was determined ex vivo.


RESULTS
Plasma cholesterol increased in all cholesterol-fed pigs but was associated with increased markers of oxidative stress only in HC pigs. Myocardial perfusion increased in response to adenosine in normal and HC + AO (+37 +/- 13% and +58 +/- 22%, respectively, p < 0.05 vs. baseline) but not in HC, whereas vascular permeability index increased only in HC pigs (+ 92 +/- 25%, p = 0.002). In HC animals, tissue endogenous oxygen radical scavengers and antioxidant vitamins were depleted and LDL oxidizability enhanced, but both were normalized in HC + AO pigs. Myocardial perfusion response was directly, and permeability inversely, associated with plasma and tissue vitamin concentrations.


CONCLUSIONS
This study demonstrates that experimental HC is associated with blunted myocardial perfusion and increased vascular permeability responses in vivo to increased cardiac demand, which may be partly mediated by a shift in oxidative status.
Rodriguez-Porcel
M
M
Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Lerman
A
A
Best
P J
PJ
Krier
J D
JD
Napoli
C
C
Lerman
L O
LO
D000818:Animals; D002199:Capillary Permeability / Q000502:physiology*; D003324:Coronary Artery Disease / Q000503:physiopathology*; D003326:Coronary Circulation / Q000502:physiology*; D004036:Diet, Atherogenic; D016166:Free Radical Scavengers / Q000097:blood*; D006937:Hypercholesterolemia / Q000503:physiopathology*; D018384:Oxidative Stress / Q000502:physiology*; D013552:Swine; D014057:Tomography, X-Ray Computed; D016277:Ventricular Function, Left / Q000502:physiology
D016166:Free Radical Scavengers