Enhanced vascular contractility and diminished coronary artery flow in rats made hypertensive from diet-induced obesity.
OBJECTIVE
To determine whether obesity-induced hypertension was associated with alterations in vascular contractility and/or cardiac function.


METHODS
Male Sprague-Dawley rats were fed either a low fat (LF; 11% kcal as fat) or a moderately high fat (MHF; 32% kcal as fat) diet for 11 weeks.


METHODS
Body weight; mean arterial pressure; angiotensin peptides; mesenteric contractile response to phenylephrine (PE), potassium chloride (KCl), serotonin, angiotensin II (AngII), calcium chloride; baseline and isoproterenol-induced cardiac contractility; baseline and isoproterenol-induced coronary artery blood flow.


RESULTS
Rats fed the MHF diet segregated into obesity-prone (OP) and obesity-resistant (OR) groups. OP rats exhibited elevations in mean arterial pressure (MAP) and elevations in systemic concentrations of angiotensin peptides. Mesenteric arteries from OP rats exhibited a greater contractile response to PE, KCl and serotonin (5-HT). Heightened responses to PE persisted in arteries from OP rats even after normalization of the response to KCl. In contrast, the response of permeabilized mesenteric arteries to a maximal concentration of calcium was similar in rats from each group. Isolated perfused hearts exhibited similar baseline and isoproterenol-induced contractility in rats from each group. However, isoproterenol was unable to increase coronary artery blood flow in hearts from OP rats.


CONCLUSIONS
Enhanced vascular reactivity may contribute to obesity-induced hypertension, while reductions in coronary artery relaxation would impair the ability of the heart to respond to increased myocardial demand.
Boustany-Kari
C M
CM
Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY 40536-0200, USA.
Gong
M
M
Akers
W S
WS
Guo
Z
Z
Cassis
L A
LA
D000809:Angiotensins / Q000097:blood; D000818:Animals; D001794:Blood Pressure; D003331:Coronary Vessels / Q000503:physiopathology*; D004032:Diet / Q000009:adverse effects; D018752:Diet, Fat-Restricted; D006973:Hypertension / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008638:Mesenteric Arteries / Q000503:physiopathology; D009765:Obesity / Q000097:blood / Q000150:complications*; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction; D014664:Vasodilation; D015430:Weight Gain / Q000502:physiology
D000809:Angiotensins