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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Dietary Prevention of Obesity-related Disease Research » Research » Publications at this Location » Publication #98548
Title: RELATIONSHIP BETWEEN DIETARY COPPER CONCENTRATION AND ACETYLCHOLINE-INDUCEDVASODILATION IN THE MICROCIRCULATION OF RATS

Author
item SCHUSCHKE, D - UNIVERSITY OF LOUISVILLE
item PERCIVAL, S - UNIVERSITY OF FLORIDA
item Saari, Jack
item MILLER, F - UNIVERSITY OF LOUISVILLE

Submitted to: Biofactors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Changes in the diameter of blood vessels affect blood flow to the tissues they serve and also influence blood pressure. The ability of blood vessels to increase in diameter is impaired in dietary copper deficiency, which may reduce blood flow to tissues or cause high blood pressure. Previous studies have only examined this effect in severe dietary copper deficiency. The purpose of the present study was to observe dilation of blood vessels in rats fed graded amounts of copper in their diets to determine the threshold copper intake at which altered dilation begins to take place. Of four levels of dietary copper concentration (an adequate, two marginally-deficient and a severely-deficient diet) only the severely- deficient diet caused altered blood vessel dilation. However, because each rat's copper status (as assessed by liver copper concentration) responds differently to a given diet we were able to define a continuous relationship between liver copper and ability of blood vessels to dilate which revealed a specific level of liver copper above which dilatory capacity remains normal. This relationship will be useful as a functional measure of assessing copper status in laboratory animals.

Technical Abstract: Dietary copper deficiency has been shown to significantly reduce acetylcholine-induced, nitric oxide-mediated vascular smooth muscle relaxation. The current study was designed to examine the relative relationship between dietary copper and the vasodilator response in the microcirculation of the rat. Male weanling rats were fed a purified basal diet supplemented with 6.0, 3.0, 1.5 or 0.0 ug Cu/g diet for 4 weeks to provide an adequate, two marginal, and deficient intakes of dietary copper. Arteriole dilation in response to increasing concentration of acetylcholine (Ach, 10**-7 to 10**-4M) was measured in the invivo cremaster muscle microcirculation for each dietary group. Liver copper and both aortic and erythrocyte Cu,Zn-SOD activity were used as indices of systemic copper status. Dilation to the increasing concentrations of Ach was only different in the 0 ug Cu supplemented group. However, the results showed an exponential increase in 10**-5 M Ach-induced vasodilation as liver copper concentration increased from 0 ug Cu/g dry wt. This relationship suggests that dilation is attenuated at liver Cu concentrations below 5 ug/g dry wt. These results indicate that Ach- induced vasodilation is copper-dependent but that the pathway is not very sensitive to short-term marginal restriction of copper intake.