Interaction of lead acetate with atrial natriuretic factor in rats

Lead exposure alters cardiovascular function and has been implicated in the etiology of hypertension. Therefore it was of interest to study the short term effect of lead treatment on atrial natriuretic factor (ANF), a hormone which produces vascular smooth muscle relaxation and natriuresis. Male Sprague Dawley rats were randomly divided into 5 groups containing 4 animals each and injected intraperitoneally with normal saline (control), 0.01, 0.1, 0.5 or 1.0 mg/kg of body weight with lead acetate solution twice a day for 7 days, and then maintained for a period of 30 days. During this period water consumption and urine volume were measured daily. At the end of the 30 day period, immunoreactive levels of ANF in hypothalamus, atria and plasma were measured by radioimmunoassay. Lead treatment did not alter water consumption, but significantly decreased urine output. At all doses, lead produced a decrease in hypothalamic content of ANF and slightly increased atrial levels. The content of ANF in plasma was decreased. The changes in ANF content indicate that lead interacts with the hormonal regulation of the cardiovascular system and these observations may relate to the cardiovascular toxicity of this heavy metal.