Role of cadmium-induced lipid peroxidation in the kidney response to atrial natriuretic hormone.

In order to investigate the role of increased lipid peroxidation in the development of cadmium-induced hypertension, 30 male albino rats were exposed to drinking water containing 15 micrograms/ml cadmium for 30 days, and the results were compared with those of 30 controls. Water containing high cadmium concentrations caused a significant accumulation of the element in blood and kidneys, associated with an obvious elevation in blood pressure. The systolic and diastolic blood pressures rose from 102.8 +/- 7.0 and 81.2 +/- 3.8 mm Hg to 128.1 +/- 4.6 and 107.9 +/- 7.4 mm Hg, respectively, in cadmium-treated rats (p < 0.01). A decreased glomerular filtration rate and increased serum creatinine levels were accompanied by elevated levels of cortical and medullary thiobarbituric acid reactive substances in cadmium-induced hypertensive rats. The mean thiobarbituric acid reactive substance level rose from a control value of 211.5 +/- 64.1 to 303.3 +/- 46.3 nmol/g protein (p < 0.01) in the renal cortex due to the high intake of cadmium. Despite its obvious diuretic and natriuretic action in control animals, the bolus injection of 1.2 and 2.4 micrograms/kg atrial natriuretic peptide corrected neither elevated blood pressure nor the reduced glomerular filtration rate in rats exposed to cadmium. However, the tubular response to atrial natriuretic peptide remained unaltered. These data suggest that a lack of vascular response to atrial natriuretic peptide is one of the many putative causes of cadmium-induced hypertension, and cadmium-mediated increased lipid peroxidation may be involved in this unresponsiveness.