RESPONSIVENESS OF AORTIC RINGS OF CADMIUM-HYPERTENSIVE RATS TO ENDOTHELIN-1

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.