Date of Award

12-2003

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Dorothy Klimis-Zacas

Second Committee Member

Rodney J. Bushway

Third Committee Member

Richard Cook

Abstract

Weanling male Sprague-Dawley rats were randomly fed three different diets (n=8 per group), a control diet (AIN '93) (C), a blueberry diet (B) for 13 weeks and a reverse diet (R)(C for 13 weeks, switched to B for 8 weeks). Aortae were excised, rings were prepared, and two intact and two denuded rings were immersed in tissue baths containing physiological salt solution (PSS) at 37OC, aerated with 95% 0 2 and 5% CO2 (pH 7.4). Following equilibration and pre-conditioning under 1 Sgm preload, cumulative dose response curves were generated with six doses of the a-1 adrenergic receptor agonist L- Phenylephrine (L-Phe, 1 O-' to 3 XI o-~M). Relaxation was induced in the rings with Acetylcholine (Ach, 3 x ~ o - ~ M ) . Effective denudation was assessed by the absence of relaxation to Ach and the maximal contraction and relaxation force (Fmax) was determined. Intact arterial rings had a significantly lower Fmax than denuded rings ( 0 . 9 6 9 ~ vs. 3 . 0 7 6 ~ ) (Pc0.05). Mean Fmax of intact rings for C, B, and R groups were 1.109, 0.873 and, 0.926gm (SEM=0.0463) respectively. A two-way ANOVA demonstrated that B and R groups had a lower Fmax than C group when contracted with L-Phe (pc0.05). There were no significant differences in Fmax means of denuded rings among diet groups (p<0.05). Our results indicate for the first time that whole wild blueberries function through the endothelium to influence the contractile machinery of the rat aorta in response to an a-1 adrenergic receptor agonist.

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