The purpose of this study was to compare vascular and cardiovascular response in rats exposed to low levels of heavy metals in drinking water. Treated group was Sprague-Dawley rats exposed to drinking water from Antofagasta city, with total arsenic of 30 ppb and lead of 53 ppb for 4 months, control group was exposed to purified water by reverse osmosis. All groups drank tap water from the time of weaning. In each vascular reactivity experiment, we studied 4 to 8 adjacent aortic rings from the same animal, using the method for isometric tension measurements (Palacios et al., 2006). Animals were sacrificed by cervical dislocation. Treated group presented arsenic and lead in the hair of rats. QT interval corrected for heart rate is a sensitive biomarker for heavy metals toxicity. QT interval increased significantly in treated group compared to the control group. Treated group showed a significantly increase in systolic blood pressure, heart rate, cardiac output, and decreased the peripheral resistance, compared to the control group. Rhythmical contractions known as vasomotion occur in small resistance and larger vessels, as the aorta. This phenomenon is commonly described under pathological conditions than in physiological conditions. We hypothesize that vasomotion may contribute, in part, to regulate blood flow (Funk et al., 1983). The incubation of aortic rings with 10-7 M acetylcholine following 10-6 M phenylephrine reduced rhythmical contractions in treated group (13±3 mg maximum amplitude; P<0.001) compared to control group (41±6 mg maximum amplitude). However, the incubation of aortic rings with 10-8 M sodium nitroprusside (a nitric oxide donor; SNP) following 10-6 M phenylephrine increased rhythmical contractions in treated group (55±11 mg maximum amplitude; P<0.05) compared to control group (25±3 mg maximum amplitude). No significant differences in the relaxation properties of ACh were observed in aortic rings from treated and control groups; in both groups, the vascular relaxation was completed. Whereas, the relaxation response to SNP in treated group (121±6% of relaxation PE-induced contraction; SNP 10-7M; P<0.05) increased versus control group (99±6% of relaxation PE-induced contraction). In conclusion, these data suggest that exposure to low levels of arsenic and lead in drinking water could reduce rhythmical contractions in blood vessels and alter the cardiovascular parameters.