Cadmium administered intraperitoneally at a dose of 1 mg/kg/day for 15
days caused a significant increase in mean arterial blood pressure. E
ndothelin-1 and noradrenaline produced concentration-dependent contrac
tions of aortic rings that attained a lower maximal contraction in cad
mium-injected rats as compared with control rats (p < 0.05), On the ot
her hand, responses of aortic rings to different concentrations of pot
assium chloride did not show a significant difference between the grou
ps, The decreased responsiveness of the aortae of cadmium-hypertensive
rats to endothelin-1 and noradrenaline could either be due to an inte
raction of cadmium with receptors or intracellular signal transduction
pathways of these agents, or it may simply reflect the adaptive chang
es in vascular tissues following hypertension development.