Zinc deficiency in rats reduces the vasodilation response to bradykinin and prostacyclin

The objective of this study was to determine the effect of zinc deficiency on the blood pressure response of rats to intravenously administered doses of two chemically distinct vasodilators, bradykinin (BK) and prostacyclin (PGI2). Immature albino rats were fed a low zinc (less than 1 ppm) diet based on soybean protein, a similar control diet (100 ppm) ad libitum or the control diet, pair-fed. After 3 wk, the carotid arteries were catheterized for blood pressure measurement and graded doses of the vasodilators were injected as a bolus into a branch of the femoral vein. In one experiment graded doses (0-8 micrograms/kg body wt) of Bk and in another graded doses (0-400 ng/kg body wt) of PGI2 were injected. In a third experiment the PGI2 doses ranged from 0 to 1000 ng/kg and, in addition to the 3-wk depletion group, two groups were repleted by feeding the control diet for 1 or 4 d. The low zinc diet induced zinc deficiency as evidenced by low rates of gain and low plasma zinc levels and significantly (P less than 0.05) decreased the blood pressure response (Emax) to both BK and PGI2. Pair feeding had no significant effect on the response; the Emax values as determined by double-reciprocal plots of the data were unchanged by the quantity of control diet consumed. Short-term repletion did not restore the PGI2 response to control values. The data are interpreted as suggesting that zinc deficiency impairs the function of vasodilator receptors in the rat vasculature.